南京市不同纯林群落结构参数与夏季降温增湿效应关系研究

Correlation between community structure parameters of pure forests and temperature reduction and humidity increase in summer

关键词:  纯林群落, 热岛效应, 郁闭度, 疏透度, 虚拟变量回归

Key words:  pure forests, thermal island effect, canopy density, canopy porosity, dummy variable regression

摘要:

以往关于植物降温增湿效应主要基于绿带等大尺度测量和利用光合仪对叶片进行微观测量分析研究,模糊了植物群落结构差异的影响。该研究基于纯林群落的小尺度实测,采用stata虚拟变量回归分析法,探讨了降温增湿作用与群落疏透度、郁闭度的影响关系,并提出群落参数的最优阈值。结果表明:郁闭度和降温、增湿作用均呈显著的正相关,而疏透度和降温、增湿作用分别呈正相关和负相关,但影响都不显著。郁闭度在0.81～0.85,疏透度在0.31～0.35时,植物群落降温作用和增湿作用最优。同时,该文将树种类型作为一个相关因素,得出在降温作用上,枫香林和紫荆林的降温效果和广玉兰林相比无显著差异,而樱花林、鸡爪槭林、香樟林、红枫林的降温效果呈极显著性差异; 在增湿作用上,桂花林、香樟林和红枫林的增湿效果和广玉兰林相比无显著差异,而乌桕、紫荆林的增湿效果差异显著。该研究结果为通过城市绿化建设缓解热岛效应的植物配置选择提供了科学依据,同时为城市绿地缓解热岛效应评价体系提供了量化的参考模式。

Abstract:

In the early research, the temperature reduction and humidity increase of plants were mainly based on big scale measurement such as green belt and microcosmic research in the scale of leaves in use of photosynthesis equipment, ignoring the effects of tree types and structural characteristics of communities in the dimension of quantification. We investigated the correlation among the effects of temperature reduction and humidity increase, canopy porosity and density based on small scale of pure forest, using dummy variable regression analysis. Furthermore, in order to obtain certain conclusion in the range of our research, we also put forward the optimal interval of structural parameter. The results showed canopy density was significantly positively correlated with both temperature reduction and humidity increase. While canopy porosity was positively correlated with temperature reduction and negatively correlated with humidity increase, but there was no significant difference. The pure forests could elaborate maximum function of releasing thermal island effect when canopy porosity ranged from 0.81 to 0.85 and canopy density ranged from 0.31 to 0.35. At the same time, we took the types of pure tree as related factors. The results showed there was no significant difference among Liquidambar formosana, Cercis chinensis and Magnolia grandiflora. And we also found significant difference appeared in Cerasus, Acer palmatum, Cinnamomum camphora and Acer palmatum ‘Atropurpureum' and Cerasus when it comes to temperature reduction effect. As for humidity increase that the pure forests played, we can see Osmanthus fragrans, Cinnamomum camphora, Acer palmatum ‘Atropurpureum' showed no difference compared to Magnolia grandiflora while there were significant differences between Sapium sebiferum and Cercis chinensis. This study provides a scientific basis for the selection of plant configurations to alleviate the heat island effect through urban greening, and provides a quantitative reference model for the urban green space to mitigate the heat island effect evaluation system, which has far-reaching impact in the ecology field.