中国森林凋落物分解速率的空间格局及主控因子:基于最优线性混合模型

Spatial pattern and main control factors in forest litter decomposition in China-A optimal linear mixed-effect model

基于与中国森林生态系统凋落物的分解速率有关的国内外文献资料,共收集覆盖热带、亚热带与温带3大气候区的569个分解速率记录,在此基础上建立了最优线性混合模型,分析了环境因子、凋落物基质质量和自身物理特征对凋落物分解速率的影响,揭示了影响凋落物分解的主控环境因子和空间格局差异.结果表明:分解速率随温度、降水、初始N、K质量分数的增加而增加,随海拔、纬度、分解时间、初始C质量分数、w(C)/w(N)、w(木质素)/w(N)、w(C)/w(P)的增加而减小;天然林和人工林凋落物分解速率无显著差异,阔叶林分解快于针叶林,针阔混交林与针叶林分解无显著差异,凋落物枝的分解速率显著低于其他组分;在全国大的空间尺度上,环境因素很重要,它们能够解释森林凋落物分解速率85%的变异,其中网孔、分解时间和海拔是森林凋落物分解的主控因子,而网孔和温度、网孔和海拔、海拔和分解时间分别为阔叶林、针叶林和针阔混交林的分解速率的主控因子.反演的中国森林凋落物的分解速率存在较大的空间异质性,其值大多为0.2~2.0.

From published data on litter decomposition in Chinese forest ecosystem,569 decomposition rates covering tropical,subtropical and temperate zones were obtained.A optimal linear mixed-effect model was established to analyze the effect of environmental factor,litter substrate quality,physical characteristics on litter decomposition rates.The main control environmental factors affecting litter decomposition was revealed.The decomposition rates were found to have a tendency to increase with temperature,precipitation,initial N and K content,and to decrease with altitude,latitude,decomposition time,initial C content,C/N,C/P and lignin/N ratio.No significant difference was found in litter decomposition rates in planted forest and natural forest.The decomposition rates of broad-leaved forest were found to be faster than coniferous forest,no significant difference was found between broad-leaved mixed forest and coniferous forest.The decomposition rates of litter branches were significantly lower than other components.On large spatial scale,environmental factors were very important,which could explain 85%of the variation in the rate of forest litter decomposition.Mesh,period and altitude are the main control factors of forest litter decomposition.The main control factors of litter decomposition rate in broad-leaved forest,coniferous forest and coniferous and broad-leaved forest respectively were found to be mesh and temperature,mesh and altitude,altitude and period respectively.Decomposition rates of Chinese forest litter have a large spatial heterogeneity,varying from 0.2-2.0.