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Ability evaluation of coniferous forest aboveground biomass inversion using Sentinel-2A multiple characteristic variables
Guo Zhengqi, Zhang Xiaoli, Wang Yueting
Corrected proof  doi: 10.12171/j.1000-1522.20200097
[Abstract](20) [FullText HTML](8) [PDF 1048KB](6)
  Objective  Forest biomass is the key factor to measure forest carbon reserves. Therefore, accurate estimation of forest biomass is helpful for forest management and resource utilization. The data from Sentinel-2A provide new opportunities for biomass estimation and monitoring due to rich spectral information and high spatial resolution. In this paper, we evaluated the ability of various parameters to estimate aboveground biomass of coniferous forest , and completed regional-scale forest biomass estimation based on Sentinel-2A.  Method  Selecting the coniferous forest of Wangyedian Forest Farm in Chifeng City, Inner Mongolia of northern China as the research object, this research extracted spectral reflectance, vegetation index and biophysical parameters in Sentinel-2A. Then we set up multiple stepwise regression equations by data types to estimate biomass. In addition, the elevation factor was added to improve the accuracy of model.  Result  The results showed that: 1) the model built with multiple types of parameters had the highest accuracy, with R2 reaching 0.765 and RMSE was 39.49 t/ha; 2) among the models established by spectral reflectance, vegetation index and biophysical parameters, the accuracy based on the vegetation index was higher, indicating that the vegetation index had a greater impact on coniferous forest aboveground biomass estimation than the spectral reflectance and biophysical parameters; 3) for all the models of our research, elevation always improved accuracy.  Conclusion  The retrieved above biomass from Sentinel-2A spatial distribution is basically consistent with the actual situation, which shows that the coniferous forest aboveground biomass inversion is meaningful for regional forest resource monitoring.
Scale conversion of photochemical reflectance index based on PROSPECT and 4-scale models
Yu Ying, Liu Min, Fan Wenyi, Wei Tiantian, Cheng Tenghui, Jiang Bo, Zhang Yue
Corrected proof  doi: 10.12171/j.1000-1522.20190190
[Abstract](80) [FullText HTML](27) [PDF 1602KB](7)
  Objective  Photochemical reflectance index (PRI) plays an important role in accurately estimating photosynthetic light use efficiency (LUE). However, at different levels, such as leaf, canopy and landscape levels, the relationship between PRI and LUE and their influencing factors are different. The spectra obtained by the sensor are pixel and canopy spectra. The PRI-LUE relationship model of the leaf level cannot be directly used for canopy-level data. Therefore, the canopy level PRI needs to be scale-converted to obtain the leaf level PRI.  Method  In this paper, the leaf-level PROSPECT model was used to simulate the reflectance and transmittance of the leaves considering different biochemical parameters, and then the leaf-level PRI and the simple ratio PRI (denoted as SR-PRI) were calculated. Secondly, the obtained leaf-level reflectance and transmittance were input as parameters to 4-scale model to get canopy reflectance under different LAIs, and the canopy-level PRI and SR-PRI were calculated. Finally, the regression analysis of PRI and SR-PRI in canopy and leaf level was carried out under different LAIs. The sensitivity of the influencing factors on PRI and SR-PRI at different scales was analyzed.  Result  PRI and SR-PRI of the canopy level have a good linear relationship with that of the leaf level. SR-PRI is generally better than PRI at the relationship of both levels, and the coefficients R2 is positively correlated with LAI.  Conclusion  The 4-scale model is feasible for scale conversion between canopy and leaf for PRI and SR-PRI. Canopy level PRI and SR-PRI can be transformed to leaf level by the functions established at different LAIs efficiently.
Characteristics of PwUSP1 in Picea wilsonii and its response to drought and salt stress
Liu Junling, Liang Kehao, Miao Yahui, Hu Anni, Sun Yongjiang, Zhang Lingyun
Corrected proof  doi: 10.12171/j.1000-1522.20200063
[Abstract](64) [FullText HTML](26) [PDF 1162KB](11)
  Objective  Universal stress proteins (USP) are stress-related genes which are widely reported to participate in the process of abiotic-stress response of plants. By identifying and validating the function of PwUSP1, we revealed the role of PwUSP1 in plants under drought and salt stress, thereby providing candidate genes for improving the tolerance to abiotic stress through genetic engineering in Picea wilsonii.   Method  Transient transformation of tobacco leaves was used to reveal the location of PwUSP1 in cells. Yeast two-hybrid experiment was used to determine whether PwUSP1 could form homodimers by itself. The Arabidopsis Col-0 (WT) was transferred by floral dip method to obtain homozygous PwUSP1 overexpression lines. The survival rates and water loss rates of PwUSP1 overexpression plants, wild type (WT) and empty vector (VC) were measured to analyze and compare the tolerance of different lines when plants were subjected to drought and salinity. DAB and NBT staining, the activities of SOD, POD, CAT and the content of MDA were determined to explore the potential physiological mechanism of PwUSP1 acting.  Result  Subcellular localization results showed that PwUSP1 was located in the nucleus, cytoplasm and cell membrane. Besides, the yeast two hybrid experiment showed that PwUSP1 itself can form homodimers. qRT-PCR was used to detect transgenic Arabidopsis, and the results showed that two independent homozygous lines with stable overexpression (L1, L7) were successfully obtained for further analysis. Under drought or salt stress, compared with WT and VC, PwUSP1 overexpression lines significantly improved the drought or salt tolerance of plants, and showed higher survival rates and lower water loss rates. Furthermore, overexpression of PwUSP1 obviously reduced the content of H2O2 and O2 , and simultaneously promoted the activities of antioxidant enzymes and inhibited the accumulation of MDA.  Conclusion  PwUSP1 is located in the nucleus, cytoplasm and cell membrane, and can form homodimers by itself. Under drought or salt stress, PwUSP1 improves the tolerance to abiotic stress of plants by enhancing ROS scavenging ability and inhibiting membrane lipid peroxidation.
Global potential distributing area and ecological suitability of Moringa oleifera
Yang Furong, Qi Yaodong, Liu Haitao, Xie Caixiang, Song Jingyuan
Corrected proof  doi: 10.12171/j.1000-1522.20190375
[Abstract](82) [FullText HTML](38) [PDF 1206KB](9)
  Objective  This paper aims to predict the global potential distributing area and analyze the ecological features of different suitable areas for introduction and cultivation management measures of Moringa oleifera.  Method  We predicted the potential distribution area by Maxent according to the 500 distribution points of M. oleifera, and analyzed the ecological features based on the environmental variables in different time scales and corresponding statistical method.  Result  M. oleifera was widely distributed in tropical and subtropical areas. In the northern hemisphere, it is mainly distributed in South Asia, Southeast Asia and West Africa. In the southern hemisphere, it is largely located in South Africa, South America. The variables affecting its geographical distribution were six climate factors, including three extreme temperature indicators (mean temperature of the coldest quarter (bio11), min. temperature of the coldest month (bio6) and mean temperature of the warmest quarter (bio10)); SD of temperature seasonality (bio4) indicating the temperature variation amplitude; mean temperature of the wettest quarter (bio8) denoting the hydrothermal synchronization; precipitation of the wettest quarter (bio16) representing the extreme moisture condition.  Conclusion  The potential distribution areas for M. oleifera were mainly located from north of 32°N to south of 29°S. Temperature is the main affecting environmental factor for M. oleifera distribution.
Effects of thermal treatment temperature and duration on mass loss and rupture modulus of Cunninghamia lanceolata
Zhang Jing, Qi Chusheng, Mu Jun
Corrected proof  doi: 10.12171/j.1000-1522.20200257
[Abstract](54) [FullText HTML](18) [PDF 961KB](4)
  Objective  Heat treatment can improve the dimensional stability of wood, but it will simultaneously reduce its mass and affect its mechanical properties. So it is necessary to explore the mechanism of heat treatment on wood mass and mechanical properties.  Method  In this study, flakes of Chinese fir plantation were used as the test material, and they were treated at 160, 180, 200, 220 °C and nitrogen atmosphere for 1, 2, 3, 4, 5 and 6 h, respectively. The mass loss rate (mL) and static bending strength (MOR) of treated wood were tested, characterized by ATR-FTIR and TGA. And the prediction model of mass loss and MOR during heat treating process was established.  Result  When the heat treating temperature didn,t exceed 200 ℃, it had a more significant impact on the mass loss and mechanical properties of wood than the heat treating time. When the heat treating temperature exceeded 200 °C, heat treating temperature and time had significant effects on wood mass loss and mechanical properties. The mass loss rate of Chinese fir wood showed a non-linear increase with the increase of heat treating temperature and heat treating time, and when the range of mass loss rate was between 0.2% and 17.6%, a model can be established, lnmL = 0.8 lnt + 9.35 lnT – 53.67 (t is time, T is temperature), R2 was 0.99. And the tested values were basically consistent with the predicted values. The MOR of Chinese fir wood decreased linearly with the increase of heat treating temperature and heat treating time. Compared with untreated wood, MOR decreased by 4.4%−74.8%, and a model which had a better forecast can be established, MOR = −2.57t – 0.82T + 220.44, R2 was 0.93. The MOR of heat-treated wood decreased exponentially with the increase of mass loss, and a model that accurately predict the changing trend of MOR with mass loss can be established, MOR = 65.4\begin{document}${e^{ - 20m_{\rm{L}}}}$\end{document} + 16.4, R2 was 0.95.  Conclusion  This study establishes the empirical equations between mass loss and the heat treating conditions, the MOR and the heat conditions, the mass loss and MOR of Chinese fir wood through the experimental data, which can provide reference and basis for optimization of wood heat treating process and prediction of heat-treated wood performance.
Determination of the average period of CH4 flux in a mixed plantation in Xiaolangdi Area of the Yellow River based on eddy covariance method
Yuan Wenwen, Zhang Jinsong, Meng Ping, Tong Xiaojuan, Zhou Yu, Li Pengxing
Corrected proof  doi: 10.12171/j.1000-1522.20200003
[Abstract](31) [FullText HTML](7) [PDF 668KB](9)
  Objective  The eddy covariance technique provides a useful tool to directly measure CH4 exchange between the vegetation and atmosphere. The eddy covariance data normally need to be regulated based on the actual situation of the study area for its application. An inappropriate average period can lead to the inaccurate estimation on CH4 flux. Therefore, some of the regulations were selected to obtain the suitable sampling frequency and average period.  Method  In this paper, the impact of average period on CH4 flux calculation had been analyzed in a mixed plantation in the Xiaolangdi Area of the Yellow River from July to August of 2016. CH4 flux was calculated in different average periods (15 − 720 min). CH4 flux obtained in different periods was analyzed, and the calculation of CH4 flux in different average periods was compared with that of 30 min average period. The influences of average period on the calculation of CH4 flux based on the original data (sampling frequency was 10 Hz) were examined. In addition, the Ogive function was applied to determine the low-frequency contribution to CH4 flux.  Result  The diurnal variations of CH4 flux were different in the average period of 15, 60, 120, 240, 360 and 720 min. Large differences occurred at noon and small differences occurred in the morning or evening. When the average period was shorter than 120 min, CH4 flux had same diurnal variation characteristic with 30 min value, and increased as the increase of the average period. The calculation of CH4 flux was estimated significantly inaccurately when the average period was longer than 240 min. The Ogive function increased when the averaging period was less than 15 min, and the Ogive function became gradually stable when the period was 60 min.  Conclusion  Different average periods have different influences on calculating CH4 flux. In this study, the optimal average period should be 60 min during the long-term observation, whereas the average period should be 15 min to obtain accurate CH4 flux at the daily time scale.
Experimental investigation on wave decay through vegetation patch with the quantitative generalized model of root, stem and leaf
Zeng Siyi, Chen Jie, Jiang Changbo, He Fei, Long Yuannan, Qu Ke, Deng Bin, Wu Zhiyuan
Corrected proof  doi: 10.12171/j.1000-1522.20180110
[Abstract](68) [FullText HTML](23) [PDF 988KB](9)
  Objective  Mangrove forest has become a research focus due to its functions as a newly ecological protector of shorelines. In order to quantify research the root, stem and leaf of mangrove forest, this study aims to experimentally investigate wave height decay along the quantitative generalized vegetation patch with root, stem and leaf.  Method  The wave height calculated by the formula of Kobayashi was compared with experimental data.  Result  The results showed that wave damping factors ranged from 0.02 to 0.47. The wave attenuation was lowest as the wave length of incident waves was equal to the length of the vegetation patch. And the boundary effect and wave height increment were observed as wave propagating over the vegetation patch. The relative wave height increment varied from 0 to 13%. When the submergence ratio ranged between 1.0 and 1.2, lower arrangement densities of leaves and roots resulted in higher and lower wave height increment, respectively. Additionally, the relative wave height increment was decreasing with a decreasing arrangement density of roots or leaves when submergence ratio equaled to 0.8.  Conclusion  The variation of wave height along the vegetation patch appears to depending on arrangement density, submergence ratio and wave length to the length of vegetation patch.
Inhibition effects of biocontrol bacteria strains on the pathogen of Camellia oleifera anthracnose
Zhang Ping, Li Chaoyang, Zhao Qingquan, Wang Lihai, Ma Ling
Corrected proof  doi: 10.12171/j.1000-1522.20190409
[Abstract](55) [FullText HTML](11) [PDF 1367KB](6)
  Objective  Endophytic bacteria with antagonistic action on oil tea anthracnose pathogen Colletotrichum fructicola were isolated from the fruit of Physali alkekengi, followed by the study on the antibacterial mechanism of the strain on the pathogen of Camellia oleifera anthracnose. It is expected to provide a theoretical basis for the field control of Camllia oleifera anthracnose.  Method  In this study, fourteen strains of bacteria were isolated from fruits by tissue separation isolation, and then three strains of bacteria with significant inhibitory effects on the pathogen of Camllia oleifera anthracnose were obtained with plate-screening method, including the strains of DLSB-1, DLSB-4 and DLSB-13. Subsequently, combining strain morphology, physiological and biochemical characteristics and 16S rDNA sequence alignment analysis, the strain was identified. Furthermore, based on the above test, whether the biocontrol strain can produce protease, cellulase and β-1,3-glucanase was determined, along with the observation of the mycelial growth of pathogenic hyphae fungus by antagonistic bacteria sterile fermentative liquid with microscope, and the indoor control effect of Camllia oleifera seedlings was measured indoors.  Result  It was found that all three strains of Bacillus sterile fermentative liquid could inhibit the normal growth of the pathogenic hyphae of Camllia oleifera anthracnose, thus making it tip-expanding, deformity and distorted. Besides, protease and cellulase could be produced, while β-1,3-glucanase could not be produced; when compared 5 concentrations (0.6 × 108, 1.0 × 108, 1.4 × 108, 1.8 × 108, 2.2 × 108 cfu/mL) of sterile fermentative liquid with control, it was found that the antibacterial effect on the pathogen of Camllia oleifera anthracnose was significant (P < 0.05), with the highest level of 81.14%. Moreover, the control effects of 5 concentrations of sterile fermentative liquid of strain DLSB-4 on potted Camllia oleifera seedlings were 40.2%, 43.9%, 57.7%, 68.7% and 71.1%, respectively. All these show that there is a positive correlation between good control effects as well as the concentration of sterile fermentative liquid and the control effect.  Conclusion  The three strains of biocontrol bacteria could produce antagonistic enzymes which inhibiting the growth of pathogenic bacteria hyphae of C. fructicola, thus reducing the incidence of Camllia oleifera anthracnose.
Purification and composition of heartwood pigment of Pterocarpus macrocarpus
Zhang Qingshuo, Wei Liuming, Yang Yutong, Sun Jing, Fu Yunlin
Corrected proof  doi: 10.12171/j.1000-1522.20200225
[Abstract](57) [FullText HTML](14) [PDF 1217KB](9)
  Objective  In order to provide scientific basis for forming mechanism of Pterocarpus macrocarpus heartwood, we investigated the purification process of heartwood pigment and component identification.  Method  The pigment of Pterocarpus macrocarpus heartwood was extracted by 7 solvents. The wavelength was measured to established a standard curves of the heartwood pigment concentration. In the purification process of the heartwood pigment, absorption efficiency, absorption concentration, desorption efficiency and desorption concentration of 10 kinds of macroporous resins were measured to determine the resin with the best adsorption effect. In the process of dynamic adsorption and desorption, the mass concentration of pigment was used as an indicator to explore the influence of different factors on DA-201 macroporous resin, and then determine the best adsorption process. UPLC-Q-EXCTIVE-MS was used to separate and identify the components of purified pigment.  Result  Ethanol was selected as the extraction solvent, and the chromatic aberration of solutions was 55.15. The 486 nm was used as the measurement wavelength to establish a standard curve. The optimum adsorption conditions of DA-201 were as follows: static absorption concentration was 10.07 mg/ml, absorption efficiency was 80.19%. The optimum desorption conditions of DA-201 were as follows, static desorption concentration was 7.06 mg/ml, and desorption efficiency was 70.07%. In the dynamic adsorption process of DA-201 macroporous resin, the optimal adsorption conditions for pigment were determined. The optimum conditions of desorption effect were: the adsorption flow rate was 2.0 mL/min and the mass concentration of the sample solution was 2 mg/ml. The optimum conditions of desorption effect were: the flow rate was 1 ml/min and the eluent volume was 100 mL. UPLC-Q-EXCTIVE-MS was used to separate and identify 10 flavonoids and alcohol compounds from the purified pigment, which were orientin, vitexin, genistein, resveratrol, chrysin, glycitein, isoliquiritin, nocarone, formononetin, ketoprofen.  Conclusion  DA-201 macroporous resin can purify the pigment of Pterocarpus macrocarpus heartwood effectively, and the components of the pigment was determined was determined.
Economic loss assessment of pine wilt disease in mainland China in 2017
Zhang Xu, Zhao Jingjing, Yan Jun, Fang Guofei, Huang Jixia
Corrected proof  doi: 10.12171/j.1000-1522.20190210
[Abstract](41) [FullText HTML](16) [PDF 791KB](8)
  Objective  As a kind of alien invasive organism, the spread of pine wilt disease has had a great impact on China’s forestry production and ecological environment, causing serious economic losses. Carrying out economic loss assessment of pine wood nematode disease not only provides an important basis for formulating disaster prevention and control programs and evaluating disaster control effects, but also scientifically guids various areas to effectively prevent and control pine wilt disease, which is conducive to improving the level of forest management.  Method  Through a combination of innovations, this study constructed a set of practical evaluation index system for economic loss of pine wilt disease, and based on the theory of market economics and ecosystem service value evaluation, comprehensive application of direct market method. The alternative market method and the dynamic equivalent factor method were used to quantitatively assess the economic losses of pine wilt disease in China on the provincial scale in 2017. The assessment results included direct economic losses and indirect economic losses.  Result  The evaluation results showed that the total area of pine wilt disease in China reached 85 524 ha in 2017, resulting in economic losses of about 19.5 billion CNY, including direct economic losses of 3.5 billion CNY and indirect economic losses of 16 billion CNY. The East China region was the hardest hit area of pine wilt disease, with a total disaster area of 43 883 ha, resulting in economic losses of 10.1 billion CNY, accounting for 52% of the national economic loss of pine wilt disease, of which direct economic losses accounted for 9%, indirect economic losses accounted for 43%. In 2017, the province with the most serious pine wood nematode disaster was Zhejiang Province. The province’s economic losses totaled 4.1 billion CNY, direct economic losses were 700 million CNY, and indirect economic losses were 3.4 billion CNY. The economic loss of pine wood nematode disease had shown that indirect economic losses were far greater than direct economic losses in all regions, compared with an average of 4.6 times. The direct economic losses included the loss of forest material resources, the cost of prevention and control, and the loss of invalid forestry costs. The direct economic losses per unit area were 21 800, 1 783 and 17 302 CNY/ha, respectively. Indirect economic losses included adjustment of service value loss, loss of support service value and loss of cultural service value. The average indirect economic losses per unit area were 77 981, 7 057 and 7 741 CNY/ha, respectively.  Conclusion  In 2017, China’s pine wilt disease mainly occurred in the southern part of China, East China and South China were the hardest hit areas, and Zhejiang Province and Guangdong Province respectively represented the provincial-level disaster space gathering center. The economic losses caused by pine wood nematode disasters are mainly indirect economic losses.
Spatial heterogeneity of photosynthetic characteristics in Chinese chestnut canopy
Ma Yali, Guo Sujuan
Corrected proof  doi: 10.12171/j.1000-1522.20200059
[Abstract](81) [FullText HTML](25) [PDF 1161KB](18)
  Objective  Canopy is an important part of the interaction between trees and external environment. The study on the spatial variation law of photosynthesis in different parts of chestnut canopy provides a theoretical basis for revealing chestnut canopy productivity.  Method  The 8-year-old chestnut trees were used as tested materials, the Li-6400 portable photosynthesis measurement system was used to determine the diurnal changes of photosynthesis in different canopies and positions of the chestnut canopy in July, fruit collection was carried out to determine the economic traits of nuts in September. Variance analysis, path analysis and regression analysis were done on the base of indexes.  Result  (1) The daily dynamics of photosynthetic rate (Pn) in the upper east, middle east, south middle, and lower south showed a unimodal curve distribution; the rest of the region showed a bimodal curve, and the areas showing a bimodal curve distribution all presented a “midday depression” phenomenon at 13:00. The daily dynamics of water use efficiency (WUE) in each canopy area presented a bimodal curve. (2) In the vertical direction of the canopy, the deficient vapor pressure (VpdL) and intercellular CO2 concentration (Ci) were shown as “lower > middle > upper”. The maximum values were 2.13 kPa, 274.93 μmol/mol, and the minimum values were 1.95 kPa, 258.75 μmol/mol; photosynthetic rate, stomatal conductance (Gs), transpiration rate (Tr), photosynthetically active radiation (PAR), water use efficiency and carboxylation efficiency (Vc) presented a “upper > middle > lower” phenomenon, and there were significant differences among different canopies. The SPAD and specific leaf area (SLA) had significant differences in the vertical canopy (P < 0.05), and both showed “lower > middle > upper”. (3) In different directions in the canopy, the strongest photosynthetic capacity was in the east, but the photosynthetic indexes were not significantly different compared with the vertical canopy. The SPAD only had significantly difference in the east, west and north directions. The SLA was not significantly different in different directions. (4) Path analysis showed that the main factors affecting Pn were Tr, WUE, and Vc, VpdL, Gs, air temperature (Ta), and Ci, only Ta had an inhibitory effect on the Pn, Tr and VpdL were the physiological and environmental factors that had the greatest influence on chestnut photosynthesis.(5)In the vertical canopy, the Pn was significantly or extremely significantly positively correlated with the single fruit mass, bur nut rate and yield per unit area, and the correlation coefficients were 0.872, 0.965 and 0.958, respectively. In the horizontal canopy, the Pn was significantly positively correlated with the single fruit mass and yield per unit area, and the correlation coefficients were 0.777 and 0.487, respectively. A comprehensive analysis of the horizontal and vertical canopy showed that the Pn was significantly or extremely significantly positively correlated with the single fruit mass, bur nut rate and yield per unit area, with correlation coefficients of 0.600, 0.669 and 0.532, respectively.  Conclusion  The photosynthesis of Chinese chestnut has obvious spatial heterogeneity, and the difference between photosynthetic index and fruit yield is the result of synthesis of vertical and horizontal canopy. In chestnut production, pruning should be reasonable to improve the efficiency for solar energy utilization in the lower and middle part of canopy, so as to increase the fruit yield.
Inversion exploration on forest aboveground biomass of optical and SAR data supported by parameter optimization method
Li Yun, Zhang Wangfei, Cui Junbo, Li Chunmei, Ji Yongjie
Corrected proof  doi: 10.12171/j.1000-1522.20190389
[Abstract](27) [FullText HTML](7) [PDF 984KB](9)
  Objective  Forest is the largest storage of organic carbon in the whole terrestrial carbon cycle system. Accurate estimation of forest aboveground biomass (AGB) is essential for global carbon storage analysis and estimation. This paper aims to explore the potential of optical and synthetic aperture radar (SAR) data for forest AGB inversion. In this study, Landsat8 OLI, GF-1 data were selected as optical data and advanced land observing satellite (ALOS)-1 phased array type L-band synthetic aperture radar (PALSAR)-1 data was selected as SAR data.  Method  Firstly, band ratio parameters, vegetation index parameters, and texture information were extracted from Landsat8OLI, gaofen-1 optical data and ALOS-1 PALSAR-1 SAR data, respectively. While polarization decomposition information was also extracted from ALOS-1 PALSAR-1 SAR data. Then these parameters extracted from different remote sensing data were sorted according to their importance by random forest (RF) algorithm. Finally, fast iterative feature selection method for k-nearest neighbor (KNN-FIFS) algorithm was used to analyze different feature combinations, and four models were constructed to estimate forest AGB and a cross-validation method was applied for result validation.  Result  These remote sensing data were modeled to estimate forest AGB using four characteristic parameters: vegetation factor, band ratio, texture factor and polarization decomposition information. For parameters extracted from vegetation factor, band ratio, texture factor, Landsat8 OLI data performed best than GF-1 and PALSAR-1 data with R2 = 0.50, RMSE = 33.34 t/ha. For GF-1 data, R2 was 0.36, RMSE was 37.60 t/ha, R2 was 0.45, RMSE was 35.40 t/ha for PALSAR-1 data. However, for parameters extracted from polarization decomposition, PALSAR-1data showed better performance with R2 = 0.63 and RMSE = 28.84 t/ha.  Conclusion  When the parameter extraction methods are the same, the forest AGB inversion potentials of the optical and SAR data are similar. However, when the parameter extraction method is different, for example, using polarization decomposition to extract parameters, the SAR data show better performance for forest AGB inversion.
Forest fire identification based on Sparse-DenseNet model
Zhou Lang, Fan Kun, Qu Hua, Lü Yuanyuan, Zhang Zhengyi
Corrected proof  doi: 10.12171/j.1000-1522.20190371
[Abstract](79) [FullText HTML](26) [PDF 1106KB](10)
  Objective  The frequent occurrence of forest fire brings great difficulty to forest prevention and control. Traditional forest fire identification algorithms have problems such as low accuracy and insufficient processing efficiency. At the same time, forest fire image data itself has strong complexity. It is necessary to comprehensively consider the recognition accuracy and generalization ability. For this reason, this paper uses the Sparse-DenseNet model to carry out the identification research of forest fire.  Method  Firstly, the DenseNet model was sparsely transformed, and the sparse effect was generated by randomly shielding the nodes in the Dense Block module, so that the algorithm had the advantages of reducing over-fitting, mitigating gradient disappearance and accelerating convergence speed. Secondly, when image acquisition was carried out in the forest area, due to the relative motion between the camera device and the object being collected and the effect of light and shadow, the image data may be disturbed. Therefore, this paper uses python image processing tools to transform the image. The image dataset was expanded accordingly to fit the actual application scenario. Finally, this paper compares the performance of the Sparse-DenseNet model with other classical deep learning models on the forest fire dataset and the cifar10 dataset, and observes its effects.  Result  The Sparse-DenseNet model had the characteristics of being lighter in structure, training faster, better effect of avoiding over-fitting. It had a good performance in the forest fire data set and the standard data set cifar10.  Conclusion  The Sparse-DenseNet model proposed in this paper can effectively optimize the problems existing in traditional forest models and achieve good recognition results. The accuracy rate can reach 99.33%, which is better than DesenNet’s 98.15%, and the training time is only about three-quarters of DenseNet in same round.
Extraction of tree crown parameters from high-density pure Chinese fir plantations based on UAV images
Sun Zhao, Pan Lei, Sun Yujun
Corrected proof  doi: 10.12171/j.1000-1522.20190386
[Abstract](3542) [FullText HTML](713) [PDF 937KB](72)
  Objective  Crown width is an important characteristic factor of canopy structure, which directly affects the productivity and vitality of trees. The forest canopy density is one of the important indexes to reflect forest canopy structure and density and to evaluate forest management and logging intensity. UAV has the advantages of easily getting high-resolution remote sensing images with high precision and low cost. Studying the method of extracting canopy parameters using UAV images is of great significance for improving the accuracy and efficiency of forest resource inventory and monitoring.  Method  Taking Chinese fir plantation in Jiangle Forest Farm of Fujian Province, eastern China as the research object, using the quadrotor UAV CCD image data as the data source, based on the object-oriented classification method, the canopy parameters of the Chinese fir plantation were extracted from the UAV images. Then the canopy objects were grouped into one group according to the segmentation results of the images, and the number of raster pixels of each canopy object was counted to calculate the canopy width area and canopy density.  Result  The object-oriented classification effectively extracted the crown of high canopy density stand. When the segmentation scale was 70, the segmentation of single tree had the best effect. Some single trees were lost during the segmentation process because of over-segmentation and under-segmentation. After completing the segmentation, optimizing the feature space of the segmented object and selecting appropriate classification features, finally the study area was divided into two types: canopy and forest gap. By counting the number of grid points of each object, the calculated stand factors included canopy density and crown area. With the measured data on the ground as reference, the crown area extraction accuracy was 0.829 1, and the forest canopy density measurement accuracy was 0.973 1.  Conclusion  The results show that the canopy parameter extraction based on high-resolution image of UAV is also applicable in high-canopy closed forest stands, which can effectively improve the efficiency and accuracy of forest resource survey.
Prediction model of base diameter of primary branch for Larix olgensis based on mixed effects
Jin Xiaojuan, Sun Yujun, Pan Lei
Corrected proof  doi: 10.12171/j.1000-1522.20200133
[Abstract](94) [FullText HTML](37) [PDF 2531KB](20)
  Objective   This paper aims to establish an age group-individual tree two-level primary branch diameter model for Larix olgensis using the nonlinear mixed effect model approach, and provide theoretical basis for the research on the characteristics and differences of branch diameter growth in different age groups.  Method   Out of four improved basic models, one was selected as the basic model after referring to the adjusting coefficient (\begin{document}$R_{\mathrm{a}\mathrm{d}\mathrm{j} }^{2}$\end{document}) and root mean square error (RMSE). Nonlinear mixed-effect model of the branch diameter was constructed based on the selected model. Independent data were used to verify the model fitting results, while mean absolute error (MAE) and mean relative absolute error (MRAE) were used to evaluate the model prediction ability. The prediction values of the basic model and the mixed model were compared. Simulation of the branch diameter distribution in each age group was done using the random parameters from age group level.   Result   Based on the improved Gompertz equation, the model performed the best when the age group random effects acted on parameter b, the individual tree random effects acted on parameters b, c and d at the same time, the variance-covariance structure of the random effects was generalized positive definite matrix, and the heteroscedasticity structure was power function. The adjustment coefficient (\begin{document}$R_{\mathrm{a}\mathrm{d}\mathrm{j} }^{2}$\end{document}) of the mixed model was improved, and RMSE, MAE and MRAE were all significantly reduced. The values of the adjustment coefficient, RMSE, MAE and MRAE of the final model were 0.699 8, 4.768 4 mm, 3.705 8 mm and 0.391 6 mm, respectively. The predicted values of the mixed model reflected the differences between individual trees. The distribution range of branch diameter was found increasing with the increase of age groups, and the branch diameter growth showed difference between the age groups.   Conclusion   The accuracy of the mixed effect model of branch diameter can be improved by incorporating the random effects of age groups and individual trees into the model. Simulation of the branch diameter growth using the random effect parameters in the age group level can reasonably reflect their growth patterns and differences, and also conform to the significance of the tree physiology. Therefore, the mixed effect model based on age group and individual tree level can reasonably predict the growth of primary branch diameter of Larix olgensis at different ages.
Evaluation of statistical methods for analyzing correlation relationship between rainfall and sediment yield for hydrologic method in the Xinshui River basin
Zhang Haibo, Zhang Jianjun, Zhang Jianan, Yang Yunbin, Gao Siyuan, Liu Junting
Accepted Manuscript  doi: 10.12171/j.1000-1522.20190125
[Abstract](6) [FullText HTML](1) [PDF 4712KB](0)
  Objective  Analyzing the trend and relationship between rainfall and sediment yield in the Xinshui River basin from 1958 to 2015 based on the daily rainfall and sediment yield data. The aim of this paper is to select the best statistical method according to the effect of rainfall stations spatial distribution and six statistical criteria of rainfall for calculating relationship between rainfall and sediment yield used for the “hydrographic method” base period. The six statistical criteria of rainfall including the annual rainfall, the flood season rainfall, the erosion rainfall, the mild sand-producing rainfall, the moderate sand-producing rainfall and the heavy sand-producing rainfall.  Method  Mann-Kendall method is selected to analyze the trend of rainfall and sediment yield, Double Mass Curve is applied to determine the base period of “hydrologic method”, and Pearson correlation analysis is used to compare the results of correlation between rainfall and sediment yield.  Result  There is no significant change trend of annual rainfall in Xinshui River Basin, but the annual sediment yield shows a significant decreasing trend. The Pearson correlation coefficient between rainfall and sediment yield under the six statistical standards are ordered from high to low as follows: the heavy sand-producing rainfall, annual rainfall, the erosion rainfall, the moderate sand-producing rainfall, the mild sand-producing rainfall and flood season rainfall. The contribution of rainfall with low intensity but high amount on sediment is small. The correlation coefficient between rainfall and sediment yield can be enhanced by eliminating the invalid rainfall for sediment. The correlation coefficient between rainfall and sediment yield of Wucheng, Huangtu, and Sange rainfall stations are higher, and the results of Daning, Sange rainfall stations are lower.  Conclusion  The change of annual sediment yield is directly related to the human activities such as the Three North Protection Forest Project and the construction of check dams. Sediment discharge is mainly caused by heavy rainstorm in summer and autumn. The heavy sand-producing rainfall can be used to analyze the relationship between rainfall and sediment yield, and the flood season rainfall is not suitable for the analysis of the relationship between rainfall and sediment yield. Invalid rainfall for sediment will increase the deviation of the correlation coefficient between rainfall and sediment yield. Rainfall with short time duration and high amount should be selected to analysis the correlation coefficient between rainfall and sediment yield when rainfall intensity data are scarce. The relationship between rainfall and sediment yield is influenced by the spatial distribution of rainfall stations at the watershed scale.
Research progress in influencing factors and measuring methods of 3-D characteristics of soil macropores
Meng Chen, Niu Jianzhi, Yu Hailong, Du Lingtong, Yin Zhengcong
Accepted Manuscript  doi: 10.12171/j.1000-1522.20190158
[Abstract](13) [FullText HTML](10) [PDF 600KB](5)
Macropore is the main channel for preferential flow, therefore it largely impacts the transportation of water, air, and chemical materials in soil. Recently, it has become a focus of interest for quantitative analysis and influencing factors of three-dimensional morphological characteristics of soil macropores, since it could provide fundamental explanations for water soil movement patterns and groundwater pollutions assessment. This paper examines state-of-the-art research development regarding 3-D morphological characteristics of soil macropore by revisiting the concept (Macropore volume, surface area, length, number, tortuosity, inclination angle, path number, diameter, node, connectivity, roundness, etc), quantitative measurements and software (Avizo9.0、VG Studio MAX2.2、Arc/Info 10.0、Image J, etc) and impact factors (Root system, soil animal, alternation of dry wet and freeze-thaw, human factors, etc) of soil macropore characteristics. On the basis of summarizing the current research status, this paper summarizes the relevant research conclusions, and also recommended the direction of future work by reviewing current work.
Research progress on soil erosion mechanism and ecological restoration technology in feldspathic sandstone region
Qin Fucang, Yang Zhenqi, Li Long
Accepted Manuscript  doi: 10.12171/j.1000-1522.20190430
[Abstract](11) [FullText HTML](3) [PDF 996KB](4)
The ecological protection and high-quality development of the Yellow River basin are important for the construction of ecological civilization in the new era of China. The feldspathic sandstone region is one of the regions facing the most serious water erosion in the Yellow River basin. It is also the coarse sand source area of the Yellow River. Communist Party of China and the government paid great attention to the soil and water erosion control and ecological restoration in feldspathic sandstone region. After persistent efforts through soil and water conservation for years, they have made great achievements, the effect of soil and water erosion control is remarkable and the regional ecological environment is gradually recovering, but the situation of soil erosion in the feldspathic sandstone region remains grim, the ecological environment is still weak in the feldspathic sandstone region. The plantations face the enormous risk of degradation and regeneration of plantation. There are plenty of literatures about the research of soil erosion mechanism of the feldspathic sandstone region. However, the hydrographic underlying surface of this region is complicated and the soil erosion types are diversified. It cannot meet the requirements of development of soil erosion mechanism of feldspathic sandstone region to continue using traditional methods of loess area. This article presents the history of the study on soil erosion mechanism and ecological restoration technology in feldspathic sandstone region, combining the previous research results and the author’s scientific research experiences. Systematic analysis was done on the progresses and shortcomings in the study on soil erosion mechanism and ecological restoration technology from the aspects of the internal cause of the erosion in bed rock, soil erosion mechanism, ecological restoration technology, existing problems and development direction. Five directions for future researches on soil erosion mechanism and ecological restoration technology in feldspathic sandstone region were given.
Effects of urban sewage sludge additive on growth and nutrient accumulation in Salix americana and Populus × euramericana cv. ‘74/76’ softwood cuttings
Tang Jiao, Peng Zuodeng, Jia Qingqi, Xiong Jianjun, Liu Chunhe, Feng Tianshuang, Wang Haidong
Corrected proof  doi: 10.12171/j.1000-1522.20200093
[Abstract](81) [FullText HTML](31) [PDF 957KB](8)
  Objective  In order to clarify the application effect of urban sewage sludge as an organic soil amendment on cuttings during the nursery culture, growth and nutrient accumulation in Salix americana and Populus × euramericana cv. ‘74/76’ softwood cuttings were studied at different sludge application rates.  Method  In the nursery with sand land of plain area, the same aged semi-lignified branches of Salix americana and Populus × euramericana cv. ‘74/76’ were used as materials in a completely random block design at application doses of 3 kg/m2 (T1), 6 kg/m2 (T2) and 9 kg/m2 (T3), and an untreated control (CK). Soil properties including soil bulk density and porosity were measured in advance. Survival rate in every treatment was counted at 35 days after cutting. The new shoot length and diameter of each treatment were measured at 35, 50, 65 and 80 days after cutting. Samples were sampled at the end to determine parameters in biomass, root morphology, and nutrient content.  Result  Sludge application reduced soil bulk density and increased soil porosity. For Salix americana, with the increase of sludge application, the new shoot length showed an increasing trend at the start, followed by decreasing, and then increased again. The T1 treatment promoted the growth of Salix americana cuttings’ new shoots that had the most obvious promotion effect, which was significantly higher than the control. The biomass parameters, root morphological parameters, leaf carbon (C) content and carbon to nitrogen ratio (C/N) of S. americana cuttings in the T1 treatment were also significantly higher than those in the control. Different treatments had no significant effect on the survival rate of S. americana cuttings. For Populus × euramericana cv. ‘74/76’, the T3 treatment could significantly increase the survival rate and root biomass parameters of cuttings. With the increase of sludge application, the new shoot length, root surface area, root volume, and average root diameter of Populus × euramericana cv. ‘74/76’ cuttings first increased and then decreased, and both reached the maximum in the T2 treatment. C, nitrogen (N) contents and C/N in leaves of Populus × euramericana cv. ‘74/76’ cuttings all increased after applied sludge, and the best treatment effect was T3. There was a positive relationship between the biomass parameters and root morphology parameters, the total biomass was positively correlated with the aboveground and root biomass, which were also positively correlated with the total root length, root surface area, root volume and average root diameter.  Conclusion  The proper application of urban sewage sludge is conducive to the growth of two species softwood cuttings, and also to the absorption of some nutrients by their leaves. The sludge application amount of 3 kg/m2 has the best promotion effect on S. americana cuttings. The cuttings of P. × euramericana cv. ‘74/76’ can adapt to the soil environment with a high amount of sludge, and the effect is better when the application amount is between 6 kg/m2 and 9 kg/m2.
Research on Forest Fire Smoke Detection Technology Based on Video Region Dynamic Features
Liu Changchun, Liu Pengju, Ji Yeyun
Accepted Manuscript  doi: 10.12171/j.1000-1522.20200049
[Abstract](188) [FullText HTML](131) [PDF 1047KB](7)
ObjectiveVideo surveillance is increasingly applied to the early detection of forest fire smoke. The existing video forest fire smoke detection methods are mostly based on pixel extraction of smoke characteristics for analysis and detection, but when the smoke is early or the smoke is far from the camera, the smoke only appears in a small area on the video image. Moreover, the diffusion of smoke is irregular, and the background environment is complex and changeable, resulting in insignificant pixel-based features, which makes it more difficult to automatically detect pixel-based smoke. Based on the principle of visible light video image processing, this paper proposes a forest fire video smoke detection method based on local area image dynamic characteristics to improve the accuracy and sensitivity of forest fire video smoke detection.MethodThe video images are selected as the research object. One frame per second is taken to generate an image sequence, and the image sequences are divided into multiple levels and different scales; using the principle of image signal-to-noise ratio, we calculate the signal-to-noise ratio of continuous image sequences after blocking; the adaptive threshold is obtained according to the signal-to-noise ratio of the background image, and the image block whose brightness changes in the image sequence to be detected is determined to be the suspected smoke block; the LBP texture feature of the suspected smoke block is extracted, and the support vector machine is used to distinguish the smoke area.ResultUsing the Value component of the HSV color space, smoke areas can be effectively extracted. The videos with forest fire smoke are selected to verify the proposed smoke change detection method. The analysis results show that the method can determine the image block where the smoke occurs and exclude some non-smoke interference factors.ConclusionThis paper proposes a video forest fire smoke detection technology based on brightness characteristics and LBP texture features of local area, which can accurately locate the smoke occurrence area and exclude some interference factors. The average detection recognition rate reaches more than 92%, which is helpful for real-time forest fire smoke automatic detection and improving the detection rate of forest fire smoke. It has a strong practicality.
Comparation in essential oil components of different altitudes and varieties of Paeonia rockii
Wu Yi, Hu Jianzhong, Han Xue, Yin Liqiang, Yuan Weiqiong, Zhao Qianlong, Lv Zhaolin
Accepted Manuscript  doi: 10.12171/j.1000-1522.20190304
[Abstract](0) [PDF 0KB](0)
ObjectiveThe composition of essential oil which was extracted from different altitudes and varieties of Paeonia rockii were studied, and the differences and similarities of the composition of compounds were also explored.MethodIn this experiment, Paeonia rockii essential oils were prepared from different altitudes of the same species and different varieties at same altitudes. The essential oil content and composition of Paeonia rockii were analyzed.ResultThe study has shown that different oils of different varieties of Paeonia rockii essential oil have different oil content, white Paeonia rockii essential oil has the highest oil content, reaching 10.94%, purple Paeonia rockii is the next, which is 10.31%, while the No. 3 pink Paeonia rockii essential oil has the lowest oil content, 7.47%. A total of 70 compounds were detected in three different altitude gradients (1, 2, and 3), and 54 species, 53 species, and 57 compounds were detected in the first, second, and third grounds, respectively. The ingredients were geraniol (5.07%、13.87%、13.74%), tetradecane (5.99%、9.86%、7.25%),7-dodecen-1-ol-acetate (35.16%、29.16%、25.01%), dodecane (7.26%、6.29%、7.32%) and tricosane (8.00%、6.36%、8.11%); A total of 75 compounds were detected in three different varieties (white, pink, purple) of Paeonia rockii essential oil, and 59, 54 and 62 species were detected in white, pink and purple Paeonia rockii. The main components were geraniol (3.91%、5.07%、9.52%), tetradecane (15.93%、5.99%、8.96%), 7-dodecen-1-ol-acetate (19.79%、35.16%、22.91%), dodecane (12.40%、7.26%、6.60%) and tricosane (7.83%、8.00%、6.37%). Although the five kinds of Paeonia rockii essential oils of different varieties at different altitudes are mainly composed of the above five components, the content varies greatly. At the same time, the other components in the essential oils also have large differences in species, quantity and content.ConclusionThis study can provide basic theoretical support for the selection of growth conditions, identification of species and the wide application of essential oil of Paeonia rockii.
Spatial layout of biological fuelbreaks in Jiangle County, Fujian Province of eastern China
Yuan Shuo, Li Chao, Chen Hao, Muhammad Amir, Liu Xiaodong
Corrected proof  doi: 10.12171/j.1000-1522.20190365
[Abstract](461) [FullText HTML](250) [PDF 1031KB](29)
ObjectiveSanming area of Fujian Province, eastern China is a forest fire-prone area. This study aims to reduce losses caused by fires and cutting off fire sources through the overall layout of biological fuelbreaks in the research area of Jiangle County, Sanming City of Fujian Province.MethodIn order to comprehensively plan the biological fuelbreaks in Jiangle County, we obtained the minimum control area by analyzing the spatial and temporal distribution of forest fires in Jiangle County over the past 12 years, determined the location of biological fuelbreaks through spatial analysis, hydrological analysis, and object-oriented spatial feature extraction and other methods and finally calculated the fire belt network density after selecting optimal fire-resistant tree species and determining the biological fuelbreak width based on statistics of the current status of biological fuelbreaks in Jiangle County.ResultThe density of biological fuelbreaks was finally determined to be 19.04 m/ha and the minimum control area was finally determined to be 10 ha. The final biological fuelbreaks need to be built were 3 591.67 km, including 1 846. 64 km in ridges, 384.21 km in valleys and 1 360.83 km in forest edges. The width of biological fuelbreaks of ridges was 12 m, and valleys and forest edges were both an average value, i.e. 9 m. Thus, the total area of the planned biological fuelbreaks was 3 786.49 ha. Choosing Schima superba as the major species, and Camellia oleifera and Phyllostachys heterocycla as subsidiary species after comparing the fire-resistant ability of main tree species in Jiangle County not only achieved a better result of fire prevention but also had economic benefits.ConclusionBased on the previous studies on fuelbreak construction in Fujian Province, and taking its density, minimum control area, construction location, and appropriate width into consideration, as well as the choose of fire-resistant tree species, this study has managed to optimize the spatial layout of fuelbreaks in Jangle County. This economical and pragmatical engineering, which is adaptative to local conditions will play an important role in fire prevention in Jiangle County of Fujian Province, eastern China.
Effects of nitrogen, phosphorus addition and drought on leaf stoichiometry in dominant species of alpine meadow
Fu Yiwen, Tian Dashuan, Niu Shuli, Zhao Kentian
Corrected proof  doi: 10.12171/j.1000-1522.20190469
[Abstract](620) [FullText HTML](474) [PDF 1004KB](51)
ObjectiveGlobal change has substantially changed soil nitrogen (N), phosphorus (P) and water availability, which further impacts plant growth and physiological processes. However, so far few studies have been conducted to analyze the interaction effects of soil N, P and water on plant growth and physiological traits, especially for alpine meadow plants. This study aims to reveal the impacts of N addition, P addition, drought and their interactions on plant growth, leaf N and P content and N:P ratios in dominant species of alpine meadows, providing scientific evidence for grassland management.MethodBased on an experiment of N addition (10 g/(m2· year)), P addition (10 g/(m2· year)) and drought (50% rainfall reduction) in an alpine meadow of northwestern Sichuan, we measured aboveground biomass, leaf N, P content and their ratio in Elymus nutans, Deschampsia caespitosa and Anemone rivularis. Then we analyzed the influence of different treatments and their interactions on plant biomass and leaf nutrient.ResultFor plant growth, N addition significantly increased plant biomass of three species, but the impacts of P addition, drought, and the interactions among different treatments were not significant. For leaf nutrient, N addition significantly enhanced leaf N content and N:P ratio of three species, and P addition also promoted leaf P content but reduced N:P ratio. Drought raised leaf N content of E. nutans and D. caespitosa, but had no significant effect on leaf P content and N:P ratio. The interaction of N addition and drought promoted leaf N content and N:P ratio of E. nutans and D. caespitosa. Nevertheless, the interaction of N and P addition was not significant for leaf nutrient of all species.ConclusionThis study indicates that alpine species have quite different responses of plant growth versus nutrient traits to nutrient enrichment, drought and their interactions. N input mainly facilitates plant growth, but the complex impacts of soil N, P, drought and their interactions all affect plant nutrient and stoichiometric balance. These results imply that more future studies are needed to detect the mechanisms underlying alpine plant physiological responses to the interactions of various global changes.
Diurnal variations of stand transpiration of Larix principis-rupprechtii forest and its response to environmental factors in Liupan Mountains of northwestern China
Ma Jing, Guo Jianbin, Liu Zebin, Wang Yanhui, Zhang Ziyou
Corrected proof  doi: 10.12171/j.1000-1522.20190468
[Abstract](875) [FullText HTML](577) [PDF 1799KB](63)
ObjectiveThis paper aims to examine the diurnal variations of stand transpiration and its response to environmental factors in a Larix principis-rupprechtii plantation, and to further explain the regulation mechanism of environmental conditions to the stand transpiration in short time scale.MethodA field experiment was conducted in a Larix principis-rupprechtii plantation stand located in the Xiangshuihe Watershed within the Natural Reserve of Liupan Mountains, Ningxia of northwestern China. The sap flow of sample trees was continuously monitored in the growth season (from May to October) in 2018. The meteorological and soil moisture conditions were continuously measured simultaneously. The response of hourly stand transpiration (T) to environmental factors was analyzed, and a T model coupling the effects of multiple influencing factors was established.ResultIt was shown that: (1) the response of T to solar radiation (Rs) and vapor pressure deficit (VPD) followed a binomial equation. The T firstly increased with rising Rs and VPD till to peak at the thresholds of 666.7 W/m2 and 1.86 kPa, and then gradually decreased afterwards. (2) The T response to relative extractable water (REW) of the 0-60 cm soil layer followed a saturated exponential growth function. The T increased firstly with rising REW, and then became stable when the REW was above 0.3. (3) The response functions of T each individual driving factors (Rs, VPD and REW) were determined using the upper boundary line method, and then were coupled to form the frame of T model. Thereafter, the observed data of odd-days and even-days were used for model fitting and validation. The fitted model is: T = (− 6.347 0 × 10− 5\begin{document}${R_{\rm{s}}^2}$\end{document} − 0.637 0Rs − 208.734 8) × (− 0.003 2VPD2 + 0.013 8VPD + 0.001 7) × (− 0.008 1 − 0.004 6(1 − exp(− 12.469 6REW))). The model was well calibrated (R2 = 0.74, Nash coefficient (NSE) = 0.82) and validated (R2 = 0.77, NSE = 0.84).ConclusionThe T variation can be well predict by the T model coupling the effects of solar radiation, vapor pressure deficit, and soil moisture conditions. This model can accurately predict the variation of T of Larix principis-rupprechtii plantation under changing environment. Meanwhile, the model establishment approach used here can be a reference for developing the stand transpiration model in other regions and for other tree species.
Determination and analysis of the relationship between microclimate elements and greening structures in the city streets of Shanghai: taking Xuhui District and Yangpu District as examples
Zhang Deshun, Xue Kaihua, Wang Zhen, Cao Wei, Ma Chundong
Corrected proof  doi: 10.12171/j.1000-1522.20170359
[Abstract](1279) [FullText HTML](892) [PDF 1088KB](95)
ObjectiveThis paper aims to explain the corresponding relationship between the microclimate elements and the street greening layout, guide the adaptability design of urban street green space.MethodBased on the field survey, the correlation between the microclimate factors and the street greening layout was elaborated, and the influence of several factors as solar radiation, air temperature and wind speed on vertical structure of street greening was explored in this study.Result(1) The relationship between street shade coverage and microclimatic factors: The higher the shade coverage, the better the reduction efficiency of solar radiation, The effect is most pronounced when coverage reaches more than 90 percent, And the rule characteristic of its cooling effect is more obvious, However, the excessive shade coverage makes the street space closed, resulting in a reduced cooling effect. The efficiency of wind speed reduction is more than 21% higher than that of 50% ~ 70% for the street greening with a green coverage rate of more than 90%. (2) Relationship between street greening cladding structure and microclimatic elements: In the multi-layer vertical structure, the more complex the structure is, the greater the greening amount will be, and the higher the solar radiation reduction efficiency will be. Its overall average reduction efficiency of solar radiation is 88.78%. The average daily cooling efficiency of the layered vertical structure is 8.69%. In the natural cycle of one day, the weakening efficiency of the wind speed is the best, followed by that of the tree-shrub-grass, the tree-shrub next, tree-grass third, shrub-grass is the last. The average daily wind speed reduction efficiency of the laminated structure is about 77.61%. (3) Relationship between vertical green ratio and microclimatic elements: The ratio of total green content of trees and shrubs was positively correlated with the solar radiation reduction efficiency. The higher the proportion of trees and shrubs, the higher the average cooling efficiency. During the natural cycle of a day, the closer the ratio of trees and shrubs to grass, the better the weakening effect on wind speedConclusionBased on the relationship between the layout of street greening and microclimate elements, the technical countermeasures for improving the comfort of microclimate by regulating the composition of street greening are proposed: (1) To build comfortable street summer microclimate, appropriate maintains 70 ~ 90% green shade coverage rate. (2) Shade and ventilation should be increased through a moderate greening cladding structure, but it should be avoided that it is too complicated to affect the normal ventilation. (3) According to the scientific proportion of vertical green quantity, taking into account the requirements of green shade coverage in summer and temperature increase in winter, planting deciduous trees and keeping trees and shrubs account for more than 50% of the street greening.
2020, 42(9): 1-2.  
[Abstract](12) [FullText HTML](3) [PDF 338KB](1)
Forest Sciences
Genetic evaluation on growth and branching traits of 4-year-old half-sib families of loblolly pine
Jiang Kaibin, Du Chengju, Li Sainan, Huang Shaowei, Liu Tianyi
2020, 42(9): 1-10.   doi: 10.12171/j.1000-1522.20190456
[Abstract](90) [FullText HTML](25) [PDF 964KB](10)
  Objective  Accurate genetic evaluation of loblolly pine progeny test plantation was conducted to improve the efficiency of breeding selection and genetic gain, and to determine the selected individuals for breeding population and reproduction population.  Method  More than 1800 individuals from 53 half-sibling families of loblolly pine were selected as the objects for genetic evaluation using the R and ASReml software. The genetic gain was predicted based on family breeding value or individual breeding value.  Result  There were significant genetic differences in height, DBH, volume, number of branches, mean diameter of branches and mean angle of branches among family lines of the torch pine, which showed great potential for selection. There was a positive genetic correlation among these traits (tree height, DBH, volume and mean diameter of branches), and the individual heritability was ranged from (0.118 9 ± 0.038 3) to (0.308 4 ± 0.053 2). There was a negative genetic correlation between the mean diameter of branches and the number of branches, and the individual heritability was (0.0316 ± 0.0272) and (0.0958 ± 0.0357), respectively. According to the family breeding value of volume, the offsprings of the top 10 female parents were selected as the selected population, and the predicted genetic gain was 4.63%−5.10%. However, the genetic gain was predicted to be 43.96%−48.43% based on the top 10 individuals, which were selected according to the breeding value of volume.  Conclusion  The superior families and individuals can be used as candidate materials for the next generation breeding population. The top 10 individuals of volume breeding value have higher predicted genetic gain and could be afforested by asexual propagation.
Ploidy, genotype and gender effects of functional leaf and stomatal traits on short branches in full-sib hybrids between section Tacamahaca and sect. Aigeiros of Populus
Shang Jing, Xue Yinxuan, Song Lianjun, Liu Chunhe, Li Daili, Zhang Hengyue, Feng Xuqing, Wang Jun
2020, 42(9): 11-18.   doi: 10.12171/j.1000-1522.20200095
[Abstract](46) [FullText HTML](14) [PDF 1699KB](6)
  Objective  This paper aims to analyze the inheritance and variation rules of allotriploid poplar, explore the effects of ploidy level, gender, genotype and environmental effects on the variation of short branch functional leaf and stomatal characters in full-sib diploid and triploid hybrids between section Tacamahaca and sect. Aigeiros of Populus.  Method  In this study, variations of short branch functional leaf and stomatal traits between full-sib diploid and triploid hybrids of 10-year-old clone experimental forest of P. pseudo-simonii × P. nigra ‘Zheyin3#’ and P. × beijingensis were analyzed.  Result  Clonal repeatability of short branch functional leaf and stomata was high, ranging from 0.789 to 0.960, which was controlled by strong heredity and had little environmental impact. There were very significant differences among clones in leaf and stomatal traits. The variation coefficient of leaf width and stomatal width was lower, which was a relatively stable genetic feature among the tested traits. The leaf length, leaf width, leaf area, stomatal length and stomatal width of triploid were extremely significantly larger than those of diploid, and the stomatal density was extremely significantly smaller than diploids, while the petiole length and serration number of triploids were not significantly different from diploid. There was no significant difference in leaf and stomatal traits between different gender plants. Correlation analysis results showed that leaf length, leaf width, leaf area, stomatal length and width were very significantly positively correlated with ploidy level, stomatal density was very significantly negatively correlated with ploidy level, while petiole length and serration number were not significantly correlated with ploidy level. The variance contribution rate showed that the gender effect of clones had the least influence on leaf and stomatal characters; stomatal traits were mostly affected by ploidy effect, followed by genotype effect; leaf traits were mainly affected by genotype effect, followed by ploidy and environmental effects.  Conclusion  The variation of short branch functional leaf and stomatal traits of full-sib hybrid between section Tacamahaca and sect. Aigeiros of Populus was mainly come from ploidy effect and genotype effect, but the influence of gender and environment was small. There were abundant trait variations among clones. It is necessary to carry out “large population, strong selection” breeding based on genetic determination in triploid breeding of Populus.
Leaf shedding of Populus tomentosa under drought stress based on the theory of plant segmentation hypothesis
Zhang Jinlan, Zhang Xiangxue, Ran Ran, Wu Min, Wu Shang, Jia Liming
2020, 42(9): 19-27.   doi: 10.12171/j.1000-1522.20190411
[Abstract](108) [FullText HTML](35) [PDF 879KB](18)
  Objective  Populus tomentosa is an excellent afforestation species in northern and northwestern China. Seasonal and occasional severe droughts occur in this region, and it is the most severe area of drought stress in China. P. tomentosa may fall a little leaves or even all leaves in the dry season, which can effectively reduce the evaporation of water to preserve the core organs, and grow the leaves again to survive the drought after rehydration. In this study, P. ‘Beilinxiongzhu 1’ and P. ‘Beilinxiongzhu 2’, the varieties of P. tomentosa, were used as plant materials. Based on the plant segmentation hypothesis, the causes of leaf shedding in the dry season were analyzed from the hydraulic relationship of plant organs between hydraulics segmentation and the vulnerability segmentation.  Method  The hydraulic characteristics and functional traits of stems, petioles and leaves of two varieties of P. tomentosa were compared.  Result  (1) The order of Ψ50 values of the vulnerability curves of the two trees was leaf > stem > petiole, which was in consistent with the plant segmentation hypothesis to some extent, and the leaves were more vulnerable than stems. (2) Specific leaf mass and stem wood density were carbon storage indicators. The specific leaf mass was related to leaf life and the wood density was related to the ability of anti-cavitation and embolization. Compared with the general values of other trees, P. ‘Beilinxiongzhu 1’ and P. ‘Beilinxiongzhu 2’ had smaller specific leaf mass, indicating that the leaves had a shorter life and the wood density was general, indicating that the resistance of the stem to cavitation was general.  Conclusion  The data of hydraulics and vulnerability of P. tomentosa can be explained by plant segmentation hypothesis, which showed that it can defoliate under the condition of keeping water in the stem. The lower life span of leaves and the weaker resistance of stems to cavitation and embolism also need defoliation to deal with severe drought. It reveals the hydraulic reasons for the rapid growth of P. tomentosa under the condition of sufficient water and fertilizer, and the ability to survive through the defoliation under the occasional extreme drought conditions. Of course, the regrowth of leaves may also involve special physiological and biochemical functions, which needs further study.
Construction of the height to crown base mixed model for Korean pine
Yan Yunfei, Wang Junjie, Jiang Lichun
2020, 42(9): 28-36.   doi: 10.12171/j.1000-1522.20190366
[Abstract](98) [FullText HTML](35) [PDF 777KB](17)
  Objective  Based on the data of 2 972 Korean pine trees in 63 sample plots of Korean pine plantation in Maor Mountain of northeastern China, a nonlinear mixed model was used to construct the height to crown base model of Korean pine, which provided a theoretical basis for further research on growth and yield model.  Method  Firstly, the optimal basic model was selected from eight commonly used models of height to crown base. Secondly, the influence of stand variables or individual tree variables on height to crown base was studied, and a generalized model was established. Finally, on the basis of the basic model and the generalized model, considering the effects of sample plot on the height to crown base of Korean pine, the basic mixed effect model and generalized mixed effect model of height to crown base for Korean pine were constructed. Four alternatives of height to crown base (HCB) sampling designs (the randomly selected trees and selecting the maximum, medium-size and minimum trees) and eight sample sizes (1−8 trees) were studied for sampling correction of basic mixed effect model and generalized mixed effect model respectively.  Result  Logistic model had good fitting accuracy and biological significance, and its form was simple, so it was chosen as the the optimal basic model. In addition to tree height (H) and DBH, there was a significant correlation between the basal area sum larger than subject tree (BAL), dominant height (HD), crown width (CW) and HCB, and the fitting accuracy of the model was improved obviously. The fitting effect of height to crown base generalized mixed effect model was better than that of other models. The model validation showed that when the basic mixed effect model was used to predict, it was recommended to select four samples with the smallest DBH, and when the generalized mixed effect model was used to predict, it was recommended to randomly select four samples.  Conclusion  The generalized mixed effect model is superior to the other three models in fitting effect and prediction accuracy. It is recommended that this model can be used as the height to crown base model for Korean pine. When applying generalized mixed effect model prediction, it is recommended that four samples can be randomly selected.
Relationship model between stand mean height and mean DBH for natural Quercus spp. broadleaved mixed stands
Lou Minghua, Zhang Huiru, Lei Xiangdong, Bai Chao, Yang Tonghui
2020, 42(9): 37-50.   doi: 10.12171/j.1000-1522.20190463
[Abstract](115) [FullText HTML](32) [PDF 1167KB](20)
  Objective  Considering stand density, diameter structure and tree species structure, the optimal model for stand mean height and mean DBH relationship was constructed using algebraic difference approach. It may provide a theoretical basis for site productivity estimation and sustainable management of natural mixed forests.  Method  Base algebraic difference approaches were modeled with 4 different data structure types, i.e. typeC, typeD, typeE and typeF based on Richards model using 4 inventory data of permanent sample plots in natural Quercus spp. broadleaved mixed stands. The 4 different base algebraic difference approaches were comparatively analyzed to get the optimal data structure type. Algebraic difference approach of diversity indices was constructed based on the optimal data structure type using 5 different stand density indices, including tree number (N), stand basal area (BA), stand density index (SDIr), additive stand density index (SDIa) and canopy density (CD), and the 5 different diameter diversity indices including Shannon evenness index (ShaI), Simpson index (SimI), McIntosh evenness index (MceI), Gini coefficient (GinI) and Berger-Parker index (BerI), and the 4 different species diversity indices including ShaI, SimI, MceI and BerI. The algebraic difference approach of diversity indices was comparatively analyzed to obtain the optimize algebraic difference approaches, i.e. the optimize stand mean height and mean DBH relationship.  Result  Model fitting effects of calibration data in different data structure types were sorted from best to worst, and the ranking was: typeD > typeC > typeF > typeE. Except for typeC, model coefficients b and r of the other three data structure types were significant (P < 0.01), indicating that the model fitting effects of typeD were the best. Model fitting effects of SDIr were the best. Model coefficients b0, r and cSD were significant (P < 0.01), regardless of which stand density index was used, indicating that model fitting effects of the 5 different stand density indices were reasonable. Model fitting effect of ShaI was the best. Except for GinI, model coefficients b0, r, cSDIr and cDI of the other 4 diameter diversity indices were significant (P < 0.01), indicating that model fitting effects of ShaI, SimI, MceI and BerI were reasonable. Model fitting and validation effects had little difference among the 4 species diversity indices. Model coefficients b0, r, cSDIr, cShaI and cSP of BerI were significant (P < 0.01), indicating that BerI was reasonable. However, model coefficients b0, r, cSDIr, cShaI and cSP of ShaI, SimI and MceI were not significant at the level of 0.05, indicating that ShaI, SimI and MceI were not reasonable.  Conclusion  TypeD is the best data structure type, stand density, diameter diversity and species diversity were significant for algebraic difference approach. Moreover, the model fitting effects of algebraic difference approach within SDIr, ShaI and BerI are the best, which is served as the optimize stand mean height and mean DBH relationship in natural Quercus spp. broadleaved mixed stands.
Study on forest road of fireproof blockade functions based on PyroSim
Gao Zhongliang, Li Zhi, Wei Jianheng, Long Tengteng, Wang Qiuhua, Shu Lifu
2020, 42(9): 51-60.   doi: 10.12171/j.1000-1522.20200140
[Abstract](107) [FullText HTML](40) [PDF 1231KB](21)
  Objective  Forest road network and its width is the basic demands of forestry production, transportation, and tourism. While giving maximum economic benefits, its function on forest fire patrol monitoring, emergency rescue, rapid transport of firefighters and equipment when happening fires also should be taken into account, as well as the function of block forest fire spreading and forest fire isolation.  Method  The micro-mountains model of Pinus yunnanensis was constructed using fire dynamic simulation software PyroSim with parameters including slopes of 25°, 35° and 45°, wind speed of 1 , 2.5 and 4.5 m/s, and forest-road widths of 2, 4.5 and 6 m. And with the application of belt fire source with 12 m in length and 6 m in width, and heat release rate of 4.6 × 104 kW/m2, which simulated moderate-intensity forest-fire, we aimed to study fire-isolating functions at different forest-road widths.  Result  The forest road width of 2 m failed to meet the need for fire protection and isolation. And the one with 4.5 m achieved relatively poor fire-isolating function performance. And the one with more than 35° slope and greater than 4.5 m/s wind speed was easy to lose its function. And 6 m width road got a strong fire isolation function. Comparing with the one that can better isolate medium-intensity forest-fire spreading condition can meet the one with less than 4.5 m/s wind speed and less than 45° slope. When wind speed reached more than 4.5 m/s, the fireproof blockade functions of forest-road width of 6 m may be lost. Generally, the central temperature of moderate-intensity forest fire was about 700−1 200 ℃. And corresponding heat release rate power can reach 3.0 × 105 − 9.0 × 105 kW. And it only took about 1 min to spread 10 m on the hill. And the burning rate of combustibles can reach above 40 kg/s in the 60 s.  Conclusion  It is suggested to build the road with 6 m width in P. yunnanensis district in Yunnan Province of southwestern China, which can achieve better fire-prevention benefits. And road with width of 8−10 m is highly recommended in the forest area, where the stands with higher tree height all year round suffering high wind speed and slope greater than 45°. It also approve that the feasibility of simulating forest-road fire-isolating function by constructing the fire-site model with PyroSim, the results in this study have certain guiding significance on the rational designs of forest-road constructions, such as the determinations of maximum threshold values of fire prevention functions of forest-road with indexes of densities and widths, so can achieve certain economic benefits, as well as reductions of destructive powers of forest fires.
Response of earlywood and latewood ring width of Cryptomeria japonica to climate change in Lushan Mountain, eastern China
Bai Tianjun, Liu Yuanqiu, Wen Linsheng, Pan Jun, Cao Wen, Zheng Xiling, Zou Qin, Deng Wengping
2020, 42(9): 61-69.   doi: 10.12171/j.1000-1522.20190439
[Abstract](121) [FullText HTML](40) [PDF 910KB](20)
  Objective  This paper aims to study the correlations between earlywood width, latewood width of Cryptomeria japonica and temperature as well as precipitation in Lushan Mountain of eastern China, so as to reveal the response of radial growth of C. japonica to climate, to understand the impact of climate change on forest ecosystem in this area, and to provide evidence for the protection of C. japonica and the selection of afforestation area under the condition of climate change in the future.  Method  Studying the main distribution of forest coniferous species, C. japonica in the Lushan Nature Reserve, the tree core samples of C. japonica were sampled and treated by dendrography, and the standard chronology of earlywood and latewood was established. Correlation analysis of climatic factors in Lushan area with the tree-ring standard chronology was taken.  Result  (1) All the statistical characteristics of the earlywood chronology were better than the latewood chronology. Compared with the radial growth of the latewood, the radial growth of the earlywood was more sensitive to the change of the monthly mean temperature. (2) The average annual temperature and annual precipitation in this area showed a significant increasing trend, the average temperature in each month showed an upward trend except August. (3) The radial growth of the C. japonica was mainly affected by the temperature, the lag effect of temperature on the growth of earlywood was particularly obvious. High temperature in summer (July) not only hindered the growth of ring width of earlywood in that year, but also affected the formation of earlywood in the next growing season. The increase of precipitation in growing season (April to July) was beneficial to the formation of earlywood and latewood in the growing season.  Conclusion  The changes of temperature and precipitation in different seasons affect the formation and growth of the earlywood and latewood. Under the background of future climate warming, the C. japonica forest in Lushan area may appear the phenomenon of growth decline.
Spatial distribution characteristics at small scale of soil organic carbon in topsoil of the west slope in Sejila Mountain, western China
Lian Yuzhen, Cao Lihua, Liu Heman, Yang Hong
2020, 42(9): 70-79.   doi: 10.12171/j.1000-1522.20190481
[Abstract](53) [FullText HTML](16) [PDF 1404KB](16)
  Objective  Analyzing the spatial distribution of soil organic carbon (SOC) and its density (SOCD) at small spatial scales aims to provide theoretical support for accurate estimation of carbon storage in alpine soils at large scales.  Method  Taking Carex alpine meadow (CAM), Rhododendron tanastylum shrub (RTS) and Rhododendron aganniphum shrub (RAS) lying in western slope of Sejila Mountain at altitudes of 4 200−4 400 meters as objects of research, and collecting soil samples at the depths of 0−10 cm with grid method, we analyzed spatial heterogeneity and influencing factors of SOC and SOCD.  Result  (1) The content of SOC was rich with an average up to 100.97 g/kg in the study area, and content of SOC declined in the following rank order: RAS (146.45 g/kg) > CAM (95.60 g/kg) > RTS (60.43 g/kg), while SOCD declined in the following rank order: CAM (7.34 kg/m2) > RAS (6.32 kg/m2) > RTS (4.80 kg/m2). (2) SOC fitted well spherical model while SOCD fitted well exponential model in CAM, as well as SOC and SOCD of RTS both matched spherical model. SOC and SOCD of CAM and RTS both had strong spatial autocorrelation with nugget/sill ratio in 1.46%−12.51% range, suggesting that spatial variability of SOC and SOCD was mainly caused by structural factors. In RAS, SOC and SOCD conformed to linear model, spatial variation was caused by random factors. This indicated that vegetation types may be the main factors affecting the spatial distribution of SOC in topsoil. Ranges of SOC and SOCD in CAM were 30.29 and 20.31 m, respectively, which was larger than RTS (17.68 and 17.44 m), indicating that spatial variability scales of SOC and SOCD in CAM were larger than RTS. At a sampling interval of 10 m, pure nugget effect appeared in SOC and SOCD of RAS, it may be that the spatial variability scale was less than 10 m, so a smaller scale research of SOC and SOCD in RAS was needed. (3) Kriging interpolation showed that the horizontal distribution of SOC and SOCD in CAM was affected by the moisture content with high value areas in the eastern and southern edges of the sample plot, in attention, it may also be related to the existence of slope and gully. The continuity of the horizontal distribution of SOC and SOCD in the RTS area was poor, and the degree of fragmentation was high, which may be related to the mosaic distribution of ground cover (shrub, herb, bare land). (4) Redundancy analysis showed that soil water content, soil density, and pH were the key factors affecting spatial heterogeneity of SOC and SOCD in 3 vegetation types, mechanical composition and slope were the second. However, the effect of total phosphorus was not apparent in this study.  Conclusion  SOC content of Sejila Mountain is relatively rich. The spatial heterogeneity of micro-topography, litter volume, and soil properties (water content, bulk density, etc.) at a small spatial scale significantly affect the spatial distribution and prediction of SOC and SOCD.
Tribological properties between roots and soil of five common tree species in North China
Han Chao, Ji Xiaodong, Liu Xiaoguang, Zhang Xiao, Zhao Donghui
2020, 42(9): 80-91.   doi: 10.12171/j.1000-1522.20190432
[Abstract](88) [FullText HTML](34) [PDF 1298KB](11)
  Objective  Pinus tabuliformis, Betula platyphylla, Quercus mongolica, Larix principis-rupprechtii and Ulmus pumila are widely grown and planted in the North China. Their roots play an important role in anchoring soil and preventing landslides. Therefore, it is of scientific significance to study their root soil interface friction performance.  Method  In this paper, the roots of five tree species dug from the Beigou Forest Farm of Mulan Forest Administration Bureau in Mulan Weichang County of Hebei Province, northern China were divided into several small sections according to different diameters, and the roots were buried in the soil specimen box with a dry density of 1.52 g/cm3 and a moisture content of 12.72%. The root pulling test machine developed by the plant mechanics laboratory of Beijing Forestry University was used to pull out the roots embedded in the soil, to explore the mechanism of root pulling out and analyze the factors affecting the friction force from different tree species and varied diameters.  Result  (1) There were two failure modes in the process of root pulling out. When the maximum tensile strength of root was less than the maximum friction between root and soil, the root pulling off failure will occur, otherwise, the root pulling out failure will occur. (2) The maximum friction of root system increased as a power function with the diameter increasing and the fitting degree was very high. (3) The maximum shear stress of root soil interface of Q. mongolica and U. pumila decreased with the increase of diameter, while that of B. platyphylla, L. principis-rupprechtii and P. tabuliformis increased with the increase of diameter. (4) The shear stress and displacement curve of the root soil interface of five tree species can be fitted by the improved hyperbolic model, and the shear stress of each tree species reached the peak value when the displacement was 6% of the total value.  Conclusion  The results show that different vegetation types and diameters have great influence on the soil consolidation effect of roots. The traditional prediction method of soil consolidation effect overestimates the soil consolidation effect of roots. Therefore, the influence of roots should be considered comprehensively in the construction of artificial protective forest.
Inversion of nutrient components of Spartina alterniflora based on hyperspectral data
Zhu Yi, Wu Yongbo, Zhou Ziyao, Zhang Zhiwen, An Yuting
2020, 42(9): 92-99.   doi: 10.12171/j.1000-1522.20200008
[Abstract](106) [FullText HTML](39) [PDF 1001KB](8)
  Objective  Contents of crude protein, crude fiber and crude fat are major indexes to determine the food quality of herb. The spectral reflectances and nutritional values of Spartina alterniflora were collected in Dafeng Pere David Deer Reserve in Jiangsu Province, China (core area III), and the relationship between the spectral data and the nutrient components of the plant was studied to obtain nutritional component estimation models.  Method  In March, May, July and October 2018, the hyperspectral reflectances of S. alterniflora were collected by an ASD Field Spec Pro FR2500 high spectrometer. Meanwhile, the crude protein, crude fiber and crude fat contents of S. alterniflora leaves were determined by field collection and lab work. The correlation analysis was obtained from comparison of the hyperspectral original reflectances, its first derivative reflectances and the measured values of crude protein, crude fiber and crude fat contents of S. alterniflora. In the range of 350−1 364 nm and 1 411−1 799 nm, the bands with the absolute correlation coefficient of each nutrient component contents of S. alterniflora higher than 0.7 were selected, and 8 vegetation indexes were constructed for modeling analysis, and the optimal model was selected.  Result  Multiple linear estimation with spectral first-order reflectances at 673 nm and 1 740 nm was the best for estimating crude protein content (R2 = 0.917, RMSEP =1.344), while linear estimation model with spectral first-order reflectances centered at 1 738 nm obtained optimal estimation result on crude fiber content (R2 = 0.741, RMSEP = 1.708). The crude fat content was best estimated at 1 734 and 880 nm by multiple linear estimations with first-order reflectances (R2 = 0.737, RMSEP = 0.343).  Conclusion  Among the established estimation models, models of crude protein and crude fiber have excellent estimation results for the crude protein content and crude fiber content of S. alterniflora, the estimation model of crude fat can better predict the crude fat content of S. alterniflora. The study provides a reference and technical basis for evaluating the nutritional quality of the S. alterniflora.
Landscape Architecture
Leaf water absorption and canopy rainfall interception of twenty-one plant species in Beijing
Wang Sisi, Long Jia, Ding Han
2020, 42(9): 100-110.   doi: 10.12171/j.1000-1522.20190379
[Abstract](73) [FullText HTML](21) [PDF 1395KB](10)
  Objective  The rainfall interception by plant canopy plays an important role in reducing stormwater runoff, and the water absorption performance of plant leaves is closely related to the ability of plant canopy to intercept rainfall.  Method  In order to evaluate the interception ability of plant canopy, the leaf water absorption, canopy interception quantity and canopy interception volume of 21 plant species in Beijing were calculated by water immersion experiment, field measurement and aerial image analysis.  Result  Research showed that: (1) the relationship between water absorption and immersion time was logarithmic; (2) the water absorption process of plant leaves can be divided into three stages. The water absorption process of trees and shrubs was similar. The mean water absorption of leaves at 20 min was 0.17 and 0.05 g, respectively; the mean water absorption of leaves at 80 min was 0.18 and 0.06 g, respectively; and the mean water absorption of leaves at 120 min was 0.18 and 0.06 g, respectively. The average water absorption of herb leaves was 0.13 g at 20 min, 0.27 g at 40 min, and 0.21 g at 120 min; (3) the canopy rainfall interception of 11 arbor species was between 71.30 and 738.72 g/m2, and the canopy rainfall interception of 6 shrub species was 41.79−275.28 g/m2, the canopy rainfall interception of 4 herb species ranged from 57.82 to 217.49 g/m2, and the canopy interception of evergreen conifers was significantly higher than that of deciduous broadleaved plants; (4) canopy interception of some shrubs and herbs was higher than that of some arbors, such as Buxus sinica and Iris tectorum; (5) the plant canopy interception volume was positively correlated with canopy cover area and plant canopy interception quantity, the evergreen coniferous tree + evergreen shrub + herb combination had the largest canopy interception volume; (6) the ratio of average annual rainfall interception of the Cedrus deodara +Buxus sinica + Iris tectorum community canopy to the total rainfall was 11.57%, which had a significant interception effect on small rainfall events.  Conclusion  Different plant types and configurations have an impact on urban green space rainfall interception capacity. This study can provide reference for the construction of high retention capacity plant communities and sponge city green space construction.
Forestry Engineering
Essential oil composition of Xanthoceras sorbifolium flower
Yuan Weiqiong, Hu Jianzhong, Wu Yi, Yin Liqiang, Han Xue, Wang Xiaoxue, Lü Zhaolin
2020, 42(9): 111-121.   doi: 10.12171/j.1000-1522.20200045
[Abstract](236) [FullText HTML](28) [PDF 905KB](22)
  Objective  The chemical composition of essential oil from flowers with different colors of Xanthoceras sorbifolium was studied, and the similarities and differences of the compounds in the essential oil were investigated.  Method  The essential oil was extracted from the petals of X. sorbifolium in white, pink and purple. The components of essential oil were analyzed by gas chromatography-mass spectrometry (GC-MS).  Result  The yield range of essential oil of the three flowers was between 0.042%−0.050%. The higher yield was white flower, which was (0.048 ± 0.002)%. The 96 volatile compounds were detected in three kinds of essential oil. Among the 62 compounds detected by white flower essential oil, the main components were heneicosane (31.46%), tetracosane (14.16%), eicosane (7.55%), 1-nonanal (7.28%), muscalure (4.84%), perhydrofarnesyl acetone (4.83%); among the 65 compounds detected by pink flower essential oil, the main components were heneicosane (31.96%), tetratetracontane (20.83%), 1-nonanal (6.72%), octadecane (3.86%), perhydrofarnesyl acetone (3.76%), hexadecane (3.30%); among the 47 compounds detected by purple flower essential oil, the main components were heneicosane (30.33%), hexatriacontane (25.09%), tetracosane (14.44%), eicosane (7.42%), phytol (3.95%), hexadecane (3.28%). The content of hydrocarbons in the three kinds of essential oil was significantly higher than that of other types of substances (P < 0.05). Principal component analysis (PCA) of 29 common compounds in the three kinds of essential oil can be simplified into two principal components, and the cumulative variance contribution rate was 98.112%, which can reflect most of the information on the samples.  Conclusion  There are some differences in the yield and compound composition of the essential oil in X. sorbifolium flower with different colors. In terms of yield, white flower essential oil is higher than other color flower essential oil, but the difference is not significant (P > 0.05). In terms of essential oil components, there are more types of compounds in pink flower essential oil than that in other flowers, and there are also large differences in the types and relative contents of the main compounds in each kind of essential oil. This study provides data support for the development and utilization of essential oil extracted from the petals of X. sorbifolium.
Effects of silicate impregnation modification on visual physical parameters of Chinese fir wood
Li Ping, Zhang Yuan, Wu Yiqiang, Lü Jianxiong, Yuan Guangming, Zuo Yingfeng
2020, 42(9): 122-129.   doi: 10.12171/j.1000-1522.20200189
[Abstract](62) [FullText HTML](25) [PDF 1323KB](8)
  Objective  The color, glossiness and texture of plain-sawed and quarter-sawed lumber of unmodified and silicate modified wood were measured and compared, and the effects of silicate modified treatment on the visual characteristics of Chinese fir wood were analyzed. The purpose was to provide theoretical basis for the large-scale application of silicate modified wood, guide the research and development of related products of modified Chinese fir wood.  Method  By means of colorimeter, glossmeter and other experimental equipment, the L*a*b* value, glossiness and texture of plain-sawed and quarter-sawed lumber with a specification of 100 mm × 100 mm × 20 mm before and after modification were measured at room temperature, and the changing rule of visual physical parameters of the wood was analyzed.  Result  (1) After modification, the red green value (a*) distribution intervals of the plain-sawed and quarter-sawed lumber were 2.0−6.0, 2.5−5.5, respectively, and the yellow blue chroma value (b*) distribution intervals were 17.5−24.0, 18.0−24.0, respectively. The two groups of data were smaller than the unmodified wood. The distribution range of lightness (L) value also decreased to 61.0−71.0, indicating that the modification had a balanced color tendency and a certain influence on the lightness and darkness of Chinese fir. (2) The parallel incident glossiness (GZL), vertical incident glossiness (GZT) and glossiness ratio (GZB) of unmodified wood were 5.54%, 4.32% and 1.28, respectively, and the GZL, GZT and GZB of modified Chinese fir were 3.32%, 2.86% and 1.16, respectively. The parallel grain glossiness GZL of the two kinds of wood was slightly higher than the straight grain glossiness GZT, showing a certain linear relationship. After modification, the linear trend of glossiness was more obvious, and the data were more centralized. (3) The texture roughness, spacing and density of the modified wood were 0.55 mm, 9.51 mm and 0.06, respectively, which showed that the modification had no effect on the wood texture. The gray distribution interval of the grain and background of the modified wood was lower than that of the unmodified wood, indicating that the modified wood made the gray level of the texture and background of the wood higher. The distribution of grain and background gray level of modified wood was looser than that of the unmodified wood. Though they had a certain linear relationship, while they were not compact.  Conclusion  Silicate modification has little effect on wood color, and the wood basically maintaines its original color characteristics. In glossiness, the modified wood is slightly smaller than the unmodified wood, and the basic distribution law is the same. The effect of the modification on the grain spacing and the grain thickness is weak. The grain density of the modified wood is still the same as that of the unmodified wood. The difference between the gray value of the modified wood grain and the background gray value becomes larger, and the contrast is slightly higher, which makes the grain of the modified wood more obvious than that of the unmodified wood.
Environmental Sciences and Engineering
Purification efficiency of Ceratophyllum demersum under different planting densities in eutrophic water
Yang Lan, Niu Jianzhi, Lun Xiaoxiu, Zhu Siyu, Ao Jiakun
2020, 42(9): 130-138.   doi: 10.12171/j.1000-1522.20190447
[Abstract](113) [FullText HTML](29) [PDF 1250KB](17)
  Objective  The submerged plant Ceratophyllum demersum is one of the commonly used plants in water ecological restoration projects. Therefore, determining the planting density of C. demersum is of great significance to promote the restoration of eutrophic water and accelerate the development of underwater forests.  Method  In this study, we simulated the different densities of C. demersum, and studied the characteristics of water quality changes under different planting densities and analyzed the purification efficiency of C. demersum on total nitrogen, total phosphorus and organic matter in eutrophic water under six planting densities (36, 50, 75, 100, 110, 120 plant/m2). Finally, combined with cost analysis, the optimal planting density was selected and the thinning and harvesting time of C. demersum was determined.  Result  The plant corresponding to the density distribution of 100 plant/m2 had the highest survival rate (95.65%), with the total nitrogen removal rate of 62.86% and the total phosphorus removal rate of 74.32%. This density had the best effect on the absorption of pollutants such as nitrogen and phosphorus, and was the best planting density for aquatic ecological restoration projects. In addition, within 15 days after planting, the removal efficiency of nitrogen, phosphorus, chemical oxygen demand (COD) and other pollutants was better along with the increase of planting density in eutrophic water, and the dissolved oxygen concentration was higher. After 50 days of planting, the amount of pollutants in each configuration increased. At this time, a part of nitrogen, phosphorus and organic matter in C. demersum were released into the water with the decline of the plants, and the dissolved oxygen content decreased more rapidly.  Conclusion  Therefore, it is necessary to consider the best purification time and timely harvest in the utilization of C. demersum to achieve water restoration.
Research Methods
Effects of several assisted extraction methods on extraction effect and antioxidant activity of proanthocyanins from blueberry
Guo Tian, Zhang Na, Fu Qun, Chai Yangyang, Guo Qingqi
2020, 42(9): 139-148.   doi: 10.12171/j.1000-1522.20190466
[Abstract](108) [FullText HTML](28) [PDF 1074KB](15)
  Objective  Using wild blueberries from Daxinganling Area, northeastern China as raw materials, the effects of organic solvent extraction, ultrasonic-assisted, microwave-assisted, and light-wave-assisted extraction methods on the extraction effects, chemical structure, and antioxidant function of proanthocyanidins and phenols from blueberries were studied.  Method  The contents of proanthocyanidins, total phenols, total flavonoids and anthocyanins in the four kinds of extraction solution were determined by spectrophotometry. The structural changes of the four kinds of extraction solution were analyzed by infrared spectrum. The microstructure of the residues of blueberry treated by different ways was observed by scanning electron microscope. The total reducing capacity and the scavenging ability of DPPH, ABTS as well as hydroxyl radicals of the four kinds of extraction solution were also measured.  Result  The maximum yield of proanthocyanidins extracted by microwave-assisted method was (15.72 ± 0.03) mg/g. The results showed that there was no obvious change in the chemical structure of proanthocyanidins extracted by four methods through infrared spectrum, and the pores and folds on the surface of the residue after microwave-assisted extraction were obvious by SEM (P < 0.05). When the blueberry proanthocyanidins extracted by the four methods was adjusted to the same concentration of 30 μg/mL, there was no significant difference in total reduction ability and DPPH free radical scavenging ability (P > 0.05). The free radical scavenging percentage of DPPH was above 97%. The order of scavenging capacity of hydroxyl radicals was general solvent extraction > microwave-assisted extraction > light wave assisted extraction > ultrasonic assisted extraction. The ultrasonic assisted method had the worst scavenging effect on ABTS radicals, and the solvent extraction method had the strongest.  Conclusion  At the same concentration, the antioxidant activity of the solution from the solvent extraction is stronger, but the microwave-saaisted extraction method has the highest yield of proanthocysnins and the antioxidant activity is not significantly different from that of the solvent extraction method (P > 0.05). Microwave can promote the extraction of proanthocyanidins in a short time because of its strong ion polarization and dipole rotation, and there is no significant difference in the chemical structure and antioxidant function of proanthocyanidins after microwave treatment, so the microwave assisted method is more suitable for the extraction of proanthocyanidins from blueberry. By comparing the yields obtained when ultrasonic, microwave, and light wave treatments are performed separately and the yields after re-extraction after ultrasonic, microwave, and light wave treatments, it is found that ultrasonic, microwave, and light wave treatments dominate the extraction.

Establishment Time:1979

CN 11-1932/S

ISSN 1000-1522

Supervisor:Sinopec Research Institute of Petroleum Engineering

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