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    于淼, 陈颖, 丁康, 马嘉, 李运远. 基于CART决策树模型的北京市春季气传花粉浓度与植被空间结构关系研究[J]. 北京林业大学学报, 2023, 45(1): 121-131. DOI: 10.12171/j.1000-1522.20210302
    引用本文: 于淼, 陈颖, 丁康, 马嘉, 李运远. 基于CART决策树模型的北京市春季气传花粉浓度与植被空间结构关系研究[J]. 北京林业大学学报, 2023, 45(1): 121-131. DOI: 10.12171/j.1000-1522.20210302
    Yu Miao, Chen Ying, Ding Kang, Ma Jia, Li Yunyuan. Study on the relationship between airborne pollen concentration and vegetation spatial structure in Beijing in spring based on CART decision tree model[J]. Journal of Beijing Forestry University, 2023, 45(1): 121-131. DOI: 10.12171/j.1000-1522.20210302
    Citation: Yu Miao, Chen Ying, Ding Kang, Ma Jia, Li Yunyuan. Study on the relationship between airborne pollen concentration and vegetation spatial structure in Beijing in spring based on CART decision tree model[J]. Journal of Beijing Forestry University, 2023, 45(1): 121-131. DOI: 10.12171/j.1000-1522.20210302

    基于CART决策树模型的北京市春季气传花粉浓度与植被空间结构关系研究

    Study on the relationship between airborne pollen concentration and vegetation spatial structure in Beijing in spring based on CART decision tree model

    • 摘要:
        目的  开展气传花粉浓度与植被空间结构关系的研究,归纳总结不同花粉浓度阈值下植被空间结构,将其应用于植物群落设计及提升过程中,为北京市城市绿地设计、建造及改造提供数据支撑,对城市绿地空间环境的营造具有实际指导意义。
        方法  研究应用Durham花粉采集器于2021年04月03日—04月09日对北京市内92个采样点的气传花粉浓度进行监测,通过CART决策树算法对不同花粉浓度的植被空间进行分类,最终归纳总结出高、中、低3个花粉浓度阈值所对应的植被空间结构模式图。
        结果  (1)乔木盖度是区别不同植被空间花粉浓度的主要控制指标,其与花粉浓度的关系并非单一线性,而是呈现一定波动性。当0.698 < 乔木盖度 ≤ 0.777时,花粉浓度最小,预测值为74粒/(103 mm2);当乔木盖度 > 0.777时,花粉浓度最大,预测值为285粒/(103 mm2);当0.600 < 乔木盖度 ≤ 0.698时,花粉浓度预测值为207粒/(103 mm2);当乔木盖度 ≤ 0.600时,花粉浓度预测值为133粒/ (103 mm2)。(2)除乔木盖度外,区别不同植被空间花粉浓度的控制指标还有灌木平均高度、乔木平均高度、地被平均高度和乔木平均枝下高等高度指标,以及群落结构类型、乔木占比和地被三维绿量等指标。(3)低花粉浓度的植被空间结构主要表现为上层高大、中下层低矮,植被类型主要为分支点高的大型乔木;高花粉浓度的植被空间结构主要有两种情况,一种是上层乔木覆盖程度较低时,中下层植被茂密,另一种是上层乔木覆盖程度极高,植物群落整体浓密,植被类型主要为常绿乔木和树冠浓密的落叶乔木,以及枝杈丰富的灌木。
        结论  本研究为气传花粉致敏植物的栽植与优化改造提供科学依据,对于新建城市绿地,致敏植物尽量应用于与高花粉浓度的植被空间结构类似的群落内部;对于已建成包含气传花粉致敏植物的群落,可通过增加植物将原本为低花粉浓度的植被空间改造为高花粉浓度的植被空间,尽可能将花粉在植被空间内部滞留沉降,减少分散到城市内部的花粉量,缓解气传花粉致敏植物对过敏人群的健康威胁。

       

      Abstract:
        Objective  The research on the relationship between airborne pollen concentration and vegetation spatial structure, aiming to summarize the vegetation spatial structure under different pollen concentration sections, would be applied to the design and transformation of plant community. The conclusion can provide data support for the design, construction and transformation of urban green space in Beijing and has practical guiding significance for the construction of urban green space environment.
        Method  The research applied the Durham pollen collector to monitor the airborne pollen concentration of 92 sampling points in Beijing from April 3, 2021 to April 9, 2021. The vegetation spaces with different pollen concentrations were classified by CART, which obtained the vegetation spatial structure model maps corresponding to high, medium and low pollen concentration sections.
        Result  (1) Coverage of arbors was the main control index to distinguish the pollen concentration of different squares. And the relationship between coverage of arbors with pollen concentration was not a single linearity but a certain degree of volatility. When the coverage of arbors was between 0.698 and 0.777, the pollen concentration was the lowest, and the predicted value was 74 grain/(103 mm2). When the coverage of arbors was greater than 0.777, the pollen concentration was the largest and the predicted value was 285 grain/(103 mm2). When the coverage of arbors was between 0.600 and 0.698, the predicted value of pollen concentration was 207 grain/(103 mm2). When the coverage of arbors was less than 0.600, the predicted value of pollen concentration was 133 grain/(103 mm2). (2) In addition to the coverage of arbors, the control indicators for pollen concentrations of different vegetation space included the average height of shrubs, average height of arbors, average height of ground cover plant, average height under branches of arbors, structure types of plant communities, percentage of arbors and three-dimensional green quantity of ground cover plant, etc. (3) The vegetation spatial structure with low pollen concentration was mainly with high trees in the upper layer and low shrubs in the middle and lower layer. The vegetation type was mainly large trees with high branch points. There were two main types of the vegetation spatial structure with high pollen concentration. One was that when the coverage of upper trees was lower, the vegetation in the middle and lower layers was dense, the other was that the coverage of upper trees was very high, and the vegetation community was very dense. The vegetation types were mainly evergreen trees, deciduous trees with dense canopy, and shrubs with rich branches.
        Conclusion  The scientific basis for the planting and optimization of airborne pollen allergenic plants was provided. For new urban green space, the allergenic plants should be used as much as possible in communities with similar structures to vegetation with high pollen concentrations. For established communities containing airborne pollen allergenic plants, the original low pollen concentration vegetation space could be transformed into the high pollen concentration vegetation space by increasing plants. The pollen would be retained and settled in the vegetation space as far as possible, so the amount of pollen dispersed into the city would be reduced and the health threat of airborne pollen allergenic plants to allergic people would be alleviated.

       

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