地形和历史干扰对西双版纳勐仑地区热带森林林冠高度结构的影响

Effects of topography and historical disturbance on canopy height structure of tropical forests in Menglun,Xishuangbanna,China

以机载激光雷达为研究手段,结合1981和2021年的全色照片,利用多元回归树的方法对云南西双版纳国家级自然保护区勐仑子保护区的热带森林林冠高度结构及其与环境因子间的关系进行探讨。结果表明:勐仑子保护区西片森林可根据林冠高度结构差异而分为7类,其中包括热带季节雨林、季风常绿阔叶林、次生林和河漫滩林;潜在辐射强度、海拔、地形垂直曲率、坡度以及1981和2021年影像亮度平均值是影响林冠高度结构聚类的主要因子。以番龙眼为主要优势种的热带季节雨林在沟谷和低地地段占有最大的分布范围,而山脊和干扰迹地上则以短刺锥为优势种的季风常绿阔叶林为主。次生林地段林冠表面极为平整,结构上明显区别于天然林,30多年前的轮歇农业活动至今仍对森林外貌有着明显影响。

With the combination of airborne Lidar and panchromatic images in 1981 and 2021,we investigated the canopy height structure of tropical forests in Menglun sub-reserve in the Xishuangbanna National Nature Reserve of Yunnan Province,and analyzed its relationship with environmental factors by using multiple regression tree(MRT)method.The results showed that forests in the Menglun sub-reserve could be clustered into seven types based on canopy height structures,with tropical rainforest,monsoon evergreen broad-leaved forest,secondary forest,and flood plain forest as the main types.The potential solar radiation,altitude,terrain profile curvature,slope and the brightness value of imageries in 1981 and 2021 were main factors that drove the classification.The tropical seasonal rainforest dominated by Pometia pinnata occupied the largest area in valley and low-land.The monsoon evergreen broad-leaved forest dominated by Castanopsis echinocarpa mainly distributed in the ridge and disturbed areas.The secondary forests had homogeneous canopy surface,which was significantly different from the primary forests.The activities of swidden agriculture about three decades ago had legacy impacts on the physiognomy of secondary forests.