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1
2007, 29(2): 122-127.
Abstract：
The Xuan paper(rice paper),which is white,soft,durable and non-absorbent,is made in an 18-step process from the bark of Pteroceltis tatarinowii and rice straw,and it is entitled as "the king of all kinds of papers".However,the variation of bark quality significantly affects the production size and quality of Xuan paper in China.Based on the investigation,the effects of soil-forming rocks and sprout ages on the bark quality of P.tatarinowii were studied in this paper.The results indicated that significant differences in basic density,fiber length,fiber width,ratio of fiber length to width,cellulose content,lignin content and pentosan content were observed in the barks growing on various soil-forming rocks and in the barks with different sprout ages(α=0.05).Among the above,the basic density of bark ranged from 0.21 to 0.36 g/cm3;fiber length,fiber width,and the ratio of fiber length to width for the bark were 2 181-2 730 μm,9.8-12.0 μm and 184.8-250.5,respectively;while the cellulose content,lignin content and pentosan content were 34.0%-41.0%,9.3%-11.5% and 8.0%-9.8%,respectively.Generally,the bark growing on the soil differentiated from limestone and harvested when the sprout age is three years old is optimal for making Xuan paper.
The Xuan paper(rice paper),which is white,soft,durable and non-absorbent,is made in an 18-step process from the bark of Pteroceltis tatarinowii and rice straw,and it is entitled as "the king of all kinds of papers".However,the variation of bark quality significantly affects the production size and quality of Xuan paper in China.Based on the investigation,the effects of soil-forming rocks and sprout ages on the bark quality of P.tatarinowii were studied in this paper.The results indicated that significant differences in basic density,fiber length,fiber width,ratio of fiber length to width,cellulose content,lignin content and pentosan content were observed in the barks growing on various soil-forming rocks and in the barks with different sprout ages(α=0.05).Among the above,the basic density of bark ranged from 0.21 to 0.36 g/cm3;fiber length,fiber width,and the ratio of fiber length to width for the bark were 2 181-2 730 μm,9.8-12.0 μm and 184.8-250.5,respectively;while the cellulose content,lignin content and pentosan content were 34.0%-41.0%,9.3%-11.5% and 8.0%-9.8%,respectively.Generally,the bark growing on the soil differentiated from limestone and harvested when the sprout age is three years old is optimal for making Xuan paper.
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Abstract：
MicroRNAs (miRNAs) is a class of endogenous non-coding small molecule RNA. To analyze the biological function of Populus euphratica miR156j, miR156j precursor(peuMIR156j)was cloned and transferred into Arabidopsis thaliana, and 35S:MIR156j transgenic plants were obtained in the current work. The results showed that overexpression of miR156j increased the number of rosette leaves, leading to thick leaves and delayed flowering, which was similar to A. thaliana,rice, etc. P. euphratica miR156j conservatively played a main role in plant development. Also germination rate and growth condition of 35S:MIR156j transgenic A. thaliana under salt treatment were better than that of the wild type, and the expression assay of gene SPL6, SPL9 and SPL11 demonstrated the downregulation caused by miR156 Based on the predicted stressassociated target gene STRS2(stress response suppressor 2), we presumed that the molecular mechanism underlying the involvement of miR156 in salttolerance may be ascribed to the regulation of STRS2 expression.
MicroRNAs (miRNAs) is a class of endogenous non-coding small molecule RNA. To analyze the biological function of Populus euphratica miR156j, miR156j precursor(peuMIR156j)was cloned and transferred into Arabidopsis thaliana, and 35S:MIR156j transgenic plants were obtained in the current work. The results showed that overexpression of miR156j increased the number of rosette leaves, leading to thick leaves and delayed flowering, which was similar to A. thaliana,rice, etc. P. euphratica miR156j conservatively played a main role in plant development. Also germination rate and growth condition of 35S:MIR156j transgenic A. thaliana under salt treatment were better than that of the wild type, and the expression assay of gene SPL6, SPL9 and SPL11 demonstrated the downregulation caused by miR156 Based on the predicted stressassociated target gene STRS2(stress response suppressor 2), we presumed that the molecular mechanism underlying the involvement of miR156 in salttolerance may be ascribed to the regulation of STRS2 expression.
5
2007, 29(3): 112-119.
DOI: 10.13332/j.1000-1522.2007.03.018
Abstract：
In this study,in order to assess the impacts of the first cycle of Larix olgensis afforestation on soil organic carbon,the authors used Dunhua City in northeast China as a case region to investigate the soil carbon in seven Larix olgensis stands during different afforestation periods,with an adjacent 250-year-old natural forest as the control for the possible long term soil carbon storing in northeast China. Mineral soil was sampled and the carbon contained in forest biomass and forest floors was measured to explore the qualitative as well as quantitative changes of soil carbon.Results showed that soil carbon decreased to a minimum level of 75.87 Mg/hm2 in the first 12 years and then gradually recovered.In the 21st year after afforestation,the soil organic carbon density of forests rose to a level as high as that in the former cropland,ie 84.28 Mg/hm2.Thereafter,the soil carbon started to accumulate.Within the short time span of 33 years,the amounts of carbon lost or gained by soil were much smaller than those accumulated in forest biomass.The soil carbon accounts for 63.4% of the ecosystem carbon stock in the 250-year-old afforested stand,suggesting that nutrient-rich afforestation soils may serve as the potential sinks for carbon in long term.Particulate organic matter(POM) was a sensitive index to reflect the soil quality.In the 0-30 cm soil layer,the percentages of coarse POM for the L.olgensis and natural forests were 2.7 and 3.4 times as high as that for the cropland.The proportion of particulate organic carbon in the total soil carbon increased,which indicates an improvement of the soil quality after afforestation.
In this study,in order to assess the impacts of the first cycle of Larix olgensis afforestation on soil organic carbon,the authors used Dunhua City in northeast China as a case region to investigate the soil carbon in seven Larix olgensis stands during different afforestation periods,with an adjacent 250-year-old natural forest as the control for the possible long term soil carbon storing in northeast China. Mineral soil was sampled and the carbon contained in forest biomass and forest floors was measured to explore the qualitative as well as quantitative changes of soil carbon.Results showed that soil carbon decreased to a minimum level of 75.87 Mg/hm2 in the first 12 years and then gradually recovered.In the 21st year after afforestation,the soil organic carbon density of forests rose to a level as high as that in the former cropland,ie 84.28 Mg/hm2.Thereafter,the soil carbon started to accumulate.Within the short time span of 33 years,the amounts of carbon lost or gained by soil were much smaller than those accumulated in forest biomass.The soil carbon accounts for 63.4% of the ecosystem carbon stock in the 250-year-old afforested stand,suggesting that nutrient-rich afforestation soils may serve as the potential sinks for carbon in long term.Particulate organic matter(POM) was a sensitive index to reflect the soil quality.In the 0-30 cm soil layer,the percentages of coarse POM for the L.olgensis and natural forests were 2.7 and 3.4 times as high as that for the cropland.The proportion of particulate organic carbon in the total soil carbon increased,which indicates an improvement of the soil quality after afforestation.
6
Abstract：
The effects of Cd 2+ on rapid lightresponse curves of photochemical and nonphotochemical chloropyll fluorescence quenching parameters were investigated under different cadmium treatments based on the determination of chlorophyll fluorescence parameters. Dark fluorescence yield (F0) and maximal fluorescence yield (Fm) of Salix babylonica, S. ‘J172’ and S. leucopithecia were investigated under different concentrations of Cd2+ solutions (0,50,100,200,400 mg/L) by a MINIIMAGINGPAM chlorophyll fluorometer. The results showed that F0 and Fm significantly increased compared with control, and the two parameters reached the maximum under the stress of 200 mg/L Cd 2+ for 2 weeks. The rapid lightresponse curves of chlorophyll fluorescence parameters of the three willow (Salix spp.) trees were also measured at various light intensities. The parameters of maximal PSⅡ quantum yield (Fv/Fm), effective PSⅡ quantum yield (PSⅡ) and coefficient of photochemical quenching (qP) decreased according to the increase of light intensity. The PSⅡ and qP declined significantly under Cd 2+ stress at the same light intensity compared with control. The parameters of quantum yield of regulated energy dissipation (YNPQ), coefficient of nonphotochemical quenching (qN), and electron transport rate (ETR) increased with elevation of light intensity. The YNPQ, qN, and ETR increased sharply under Cd 2+ stress at same light intensity. No significant change was found for quantum yield of nonregulated energy dissipation(YNO) of the three willow trees with the aggrandizement of light intensity. The results indicate that S. leucopithecia shows torelence to Cd 2+ by reversible inactivation of PSⅡ reaction center.
The effects of Cd 2+ on rapid lightresponse curves of photochemical and nonphotochemical chloropyll fluorescence quenching parameters were investigated under different cadmium treatments based on the determination of chlorophyll fluorescence parameters. Dark fluorescence yield (F0) and maximal fluorescence yield (Fm) of Salix babylonica, S. ‘J172’ and S. leucopithecia were investigated under different concentrations of Cd2+ solutions (0,50,100,200,400 mg/L) by a MINIIMAGINGPAM chlorophyll fluorometer. The results showed that F0 and Fm significantly increased compared with control, and the two parameters reached the maximum under the stress of 200 mg/L Cd 2+ for 2 weeks. The rapid lightresponse curves of chlorophyll fluorescence parameters of the three willow (Salix spp.) trees were also measured at various light intensities. The parameters of maximal PSⅡ quantum yield (Fv/Fm), effective PSⅡ quantum yield (PSⅡ) and coefficient of photochemical quenching (qP) decreased according to the increase of light intensity. The PSⅡ and qP declined significantly under Cd 2+ stress at the same light intensity compared with control. The parameters of quantum yield of regulated energy dissipation (YNPQ), coefficient of nonphotochemical quenching (qN), and electron transport rate (ETR) increased with elevation of light intensity. The YNPQ, qN, and ETR increased sharply under Cd 2+ stress at same light intensity. No significant change was found for quantum yield of nonregulated energy dissipation(YNO) of the three willow trees with the aggrandizement of light intensity. The results indicate that S. leucopithecia shows torelence to Cd 2+ by reversible inactivation of PSⅡ reaction center.
7
Abstract：
ObjectiveThe effects of stand density on the community structure and species diversity of Cupressus funebris plantation and the correlation between species diversity and stand factors were explored, providing a basis for the management of Cupressus funebris plantation in Yunding Mountains, southwestern China. MethodThe research objects were five different stand densities (A−E: 500, 650, 800, 950, 1 100 tree/ha) of 60 years Cupressus funebris in Yunding Mountain, Sichuan Province, southwestern China. The vegetation was investigated by typical plot method. The community structure, species composition and species diversity index (Pielou evenness index Jsw, Simpson dominance index H', Shannon-Wiener diversity index H and species richness index D) were comprehensively analyzed. Result(1) A total of 170 species of plants were recorded in the study area, belonging to 136 genera and 68 families. The dominant species in shrub layer or herb layer under different densities were mostly shady, shade-tolerant or adaptable plants. (2) With the decrease of stand density, the trend of species diversity index in shrub layer increased first and then decreased. It reached the maximum at density B, with no significant difference except D (P > 0.05). The trend of D, H and H' in herbaceous layer increased first, then decreased, then increased and then decreased. The peak values appeared in density B and D, and there were significant differences among different densities. Stand density and canopy density were negatively correlated with shrub layer D, and significantly positively correlated with herb layer H, H' and Jsw. (3) Distribution between diameter and height structure of density A community was irregular and fluctuated, while distribution of other densities was unimodal. In density B community, medium and large individual trees accounted for a relatively large proportion of individuals, and the stability of the community was better. ConclusionThe relative optimum stand density of cypress plantation in Yunding Mountain is 650 tree/ha, which is very helpful to maintain the stability of community structure and improve the species diversity under the forest.
8
Abstract：
This paper researches the fuel vertical distribution quantitatively through the analyses of fuel loads among tree, shrub, grass and litter in major forests (Platycladus orientalis and Pinus tabulaeformis) in the mountainous area of Beijing. The relation between the vertical distribution of fuel and crown fire was quantified by using the vertical continuity indices (C) and ratings. Based on C and ratings, the hazard of crown fire was evaluated and analyzed for two coniferous forests. Results showed that P. orientalis forest(POF) had a high risk of happening crown fires; P.tabulaeformis forst(PTF) had a lower risk of happening crown fires; the fuel continuity of two coniferous forests was evaluated reasonably based on C and ratings, and C of POF was 1.002(high), while PTF was 0.893 (moderate), indicating that the risk of crown fires occurring in POF was higher than PTF. It is also shown that the model can well describe and explain the vertical continuity of forest fuels and the risk of forest fire spreading in vertical direction.
This paper researches the fuel vertical distribution quantitatively through the analyses of fuel loads among tree, shrub, grass and litter in major forests (Platycladus orientalis and Pinus tabulaeformis) in the mountainous area of Beijing. The relation between the vertical distribution of fuel and crown fire was quantified by using the vertical continuity indices (C) and ratings. Based on C and ratings, the hazard of crown fire was evaluated and analyzed for two coniferous forests. Results showed that P. orientalis forest(POF) had a high risk of happening crown fires; P.tabulaeformis forst(PTF) had a lower risk of happening crown fires; the fuel continuity of two coniferous forests was evaluated reasonably based on C and ratings, and C of POF was 1.002(high), while PTF was 0.893 (moderate), indicating that the risk of crown fires occurring in POF was higher than PTF. It is also shown that the model can well describe and explain the vertical continuity of forest fuels and the risk of forest fire spreading in vertical direction.
9
2007, 29(3): 185-188.
DOI: 10.13332/j.1000-1522.2007.03.030
Abstract：
In order to study the population dynamic and quantitative characteristics of Osmanthus fragrans in Shifengzhai of Changting County,Fujian Province,based on the life table of population and the theory of survival analysis,a static life table of O.fragrans was worked out and the curves of survival,mortality rate,lose rate mortality density function,cumulative mortality function,as well as risk rate function were drawn in this paper.Meanwhile,the life process of O. fragrans population was analyzed.Results show that the population has one peak of mortality,and survival curve of the population trends to the type of Deevey-Ⅱ.Then spectral analysis of the population dynamics of O.fragrans was made,which shows that there is a marked regularity of periodic fluctuation in the process of natural regeneration of O.fragrans.Moreover,the reasons that the population dominated in the community are related to the biological characteristics and abundant seed pool of the population,appropriate surroundings,etc.
In order to study the population dynamic and quantitative characteristics of Osmanthus fragrans in Shifengzhai of Changting County,Fujian Province,based on the life table of population and the theory of survival analysis,a static life table of O.fragrans was worked out and the curves of survival,mortality rate,lose rate mortality density function,cumulative mortality function,as well as risk rate function were drawn in this paper.Meanwhile,the life process of O. fragrans population was analyzed.Results show that the population has one peak of mortality,and survival curve of the population trends to the type of Deevey-Ⅱ.Then spectral analysis of the population dynamics of O.fragrans was made,which shows that there is a marked regularity of periodic fluctuation in the process of natural regeneration of O.fragrans.Moreover,the reasons that the population dominated in the community are related to the biological characteristics and abundant seed pool of the population,appropriate surroundings,etc.
10
2007, 29(2): 161-164.
Abstract：
The thesis probed into the factors influencing the mechanical properties of composite material,such as fiber length,dosage of rock wool,density,resin content,temperature of hot pressing and hot pressing time,etc.when using rock wool and wood fiber to make wood fiber-rock wool composites.The study shows that it is feasible to make wood fiber-rock wool composites by blending rock wool and wood fiber.The length of wood fiber,density of the products,dosage of rock wool are the main factors influencing the mechanical and fire-retardant properties of composites.With the increase of wood fiber length,the static bending strength of products increases and the internal bond strength decreases.When density increases,the mechanical properties of the products heighten linearly.When the dosage of rock wool increases,the mechanical properties of products weaken linearly and the fire-retardant performance of the products heightens linearly.Within the range of parameters which are selected for the experiment,the influence of resin content,temperature of hot pressing and hot pressing time on the mechanical properties and fire-retardant performance of the products is not obvious.
The thesis probed into the factors influencing the mechanical properties of composite material,such as fiber length,dosage of rock wool,density,resin content,temperature of hot pressing and hot pressing time,etc.when using rock wool and wood fiber to make wood fiber-rock wool composites.The study shows that it is feasible to make wood fiber-rock wool composites by blending rock wool and wood fiber.The length of wood fiber,density of the products,dosage of rock wool are the main factors influencing the mechanical and fire-retardant properties of composites.With the increase of wood fiber length,the static bending strength of products increases and the internal bond strength decreases.When density increases,the mechanical properties of the products heighten linearly.When the dosage of rock wool increases,the mechanical properties of products weaken linearly and the fire-retardant performance of the products heightens linearly.Within the range of parameters which are selected for the experiment,the influence of resin content,temperature of hot pressing and hot pressing time on the mechanical properties and fire-retardant performance of the products is not obvious.
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