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利用凋落叶空间扩散模型研究单株植物的凋落叶扩散过程,这对预测凋落叶在地表的分布格局有重要意义.本文依据浙江天童20 hm2动态监测样地植被调查数据和叶凋落量数据,分别对20种目标树种进行凋落叶空间扩散模型的拟合,以及模型适用性分析.模型假设叶凋落量和植株胸径之间服从异速生长关系,并且叶凋落量随距离呈指数降低,通过极大似然法估计模型参数.结果表明:所有树种实际叶凋落量和理论叶凋落量相关性显著;但树种间的模型预测精度相差较大,各树种理论叶凋落量解释实际叶凋落量变异的百分比为16.0%~74.0%,平均为49.3%.模型预测精度与叶凋落量数据的标准差、树种平均胸径、树种平均叶片干质量呈显著正相关.根据各树种的分布格局,使凋落物筐覆盖到不同胸径母树周围不同距离处,确定各树种的最优扩散函数,以及不断改进已有的扩散函数可以提高模型的预测精度.
It is important to predict the distribution pattern of litter on the surface of the litter by using the spatial diffusion model of litterfall.According to the 20 hm2 dynamic monitoring sample data and the leaf litter data of Zhejiang Tendoom, Fitting the spatial diffusion model of litter leaf of 20 species to the target tree and the applicability of the model.The model assumes that the leaf litter amount and plant DBH obey the allometric relationship and the leaf litter amount decreases exponentially with distance, Likelihood method was used to estimate the parameters of the model.The results showed that the correlation between the actual leaf litter and the theoretical leaf litter was significant in all tree species, but the prediction precision of the models differed greatly among the species. The leaf litter amount of each species explained the percentage of actual leaf litter variation And the average leaf diameter was 16.0% -74.0% with an average of 49.3% .The model prediction accuracy was positively correlated with the standard deviation of leaf litterfall data, the average diameter at breast height of tree species, and the average dry weight of tree species.According to the distribution pattern of each tree species, To different diameter around the mother tree at different distances to determine the optimal diffusion function of each species, as well as continuous improvement of the existing diffusion function can High prediction accuracy of the model.