【摘要】 为探究城市森林冠层结构的时空变化规律以及对林下光照分布的影响,以广东树木公园和华南农业大学树木园的典型植物群落为研究对象,依据研究区植物分布和地形特征设置6条调查样带,于2022年11月—2023年10月利用半球面影像技术连续监测群落的林冠开度（CO）、叶面积指数（LAI）、林下直射光（TDir）、散射光（TDif）和总光照（TTot）,并通过典型相关分析探讨冠层结构和林下光环境之间的关系。结果表明,各群落间CO和LAI均存在极显著差异（P<0.01）, CO的范围为11.98%～31.28%, LAI为1.50～3.03,阔叶林群落（Broad-leaved community）和南洋楹群落（Falcataria falcata community） CO随季节更替呈现先降低后增加的显著变化趋势（P<0.05）, LAI变化方向相反,其余群落变化不明显。各群落间TDir、 TDif和TTot均存在极显著差异（P<0.01）,范围分别为2.62～7.45、2.64～6.72、5.14～14.18 mol·m^-2·d^-1,除大叶相思群落（Acacia auriculiformis community） TDir和TTot的月际变化不显著外,其余群落的林下光环境参数随季节更替呈现先增加后降低的显著变化趋势（P<0.05）。林下光环境与CO呈极显著正相关（P<0.01）,与LAI呈极显著负相关, TDif对林下光环境的解释量最大。综上认为,不同群落的冠层结构和林下光环境存在显著的时空异质性,冠层结构对林下光环境有明显的控制作用,气温、光照、水分等环境因子的季节性变化和自然干扰是森林冠层季节变化的重要影响因素。更多还原

【Abstract】 To explore the spatiotemporal variation patterns of canopy structure and its impact on understory light distribution,typical plant communities in Guangdong Tree Park and South China Agricultural University Arboretum were selected as research objects. Based on plant distribution and topographic characteristics in the study area,six survey transects were established. From November 2022 to October 2023,hemispherical photography was used to continuously monitor canopy openness(CO),leaf area index(LAI),transmitted direct solar radiation(TDir),transmitted diffuse solar radiation(TDif),and transmitted total solar radiation(TTot) of the communities. The relationship between canopy structure and understory light environment was investigated using canonical correlation analysis. The results showed that there were extremely significant differences in CO and LAI among the communities(P<0. 01),with CO ranging from 11. 98% to 31. 28% and LAI ranging from 1. 50 to 3. 03. The broad-leaved community and the Falcataria falcata community showed a significant trend of first decreasing and then increasing in CO with seasonal progression(P<0. 05),while LAI showed the opposite patterns. Changes in other communities were not significant. There were extremely significant differences in TDir,TDif and TTot among the communities(P<0. 01),with ranges of 2. 62-7. 45, 2. 64-6. 72,and 5. 14-14. 18 mol·m-2·d-1,respectively. Except for the Acacia auriculiformis community,which showed no significant monthly variations in TDir and TTot,the understory light parameters of other communities exhibited a significant trend of first increasing and then decreasing with seasonal progression(P<0. 05). The understory light environment was extremely significantly positively correlated with CO(P<0. 01) and significantly negatively correlated with LAI,while TDif contributed the highest explanation for the understory light environment. In conclusion,the canopy structure and understory light environment of different communities exhibited significant spatiotemporal heterogeneity. The canopy structure played a notable controlling role in the understory light environment,and seasonal changes in environmental factors such as temperature,light,and moisture,along with natural disturbance,were important factors influencing seasonal variations in the forest canopy.更多还原