贵州喀斯特生态系统不同恢复阶段植物群落凋落物及碳氮归还动态

Dynamics of Plant Community Litter and Carbon and Nitrogen Recycling at Different Restoration Stages in Guizhou Karst Ecosystem

凋落物是森林生态系统碳库的重要组成部分,本研究对贵州普定喀斯特生态系统5种不同恢复阶段(稀灌草丛、藤刺灌丛、灌木林、乔灌过渡林、次生乔木林)植物群落的凋落物总量、凋落物组成(叶、枝、花果等)特征、凋落物量月动态及碳氮归还量进行了一年的定位观测。结果表明:稀灌草丛、藤刺灌丛、灌木林、乔灌过渡林、次生乔木林的年总凋落物量分别为726.0、3811.6、5161.0、4378.8、4604.8 kg/hm^(2),随着群落的恢复发展,凋落物总量呈现出先升高后缓降的变化趋势;各恢复阶段植物群落叶凋落物量占总凋落物量的64.2%~74.9%,枝凋落物量占总凋落物量的11.4%~18.1%,花果等凋落物量占总凋落物量的9.8%~19.5%;群落恢复初期(稀灌草丛、藤刺灌丛、灌木林)凋落物量月动态呈单峰型,而群落恢复中后期(乔灌过渡林、次生乔木林)凋落物量月动态呈双峰型,各恢复阶段植物群落的叶凋落物量与总凋落物量的月动态基本一致;C、N含量总体上表现为花果等凋落物>叶凋落物>枝凋落物,5种不同恢复阶段植物群落凋落物中C、N的年归还总量与其年总凋落物量显著正相关。

Litter is an important component of carbon pool in forest ecosystems.In this study,we conducted a oneyear positioning observation on the total litter biomass,litter components(leaves,branches,flowers and fruits)characteristics,monthly dynamics of litter biomass,and carbon and nitrogen recycling of plant communities at five different restoration stages(sparse tussock,throny shrubland,low shrubland,shrub-tree transitional forest,secondary arbor forest)of the karst ecosystem in Puding,Guizhou Province.The results showed that the annual total litter biomass of above five different successional communities were 726.0,3811.6,5161.0,4378.8,4604.8 kg/hm^(2),respectively.With the recovery and development of the community,the total litter biomass showed a trend of first increasing and then decreasing slowly.The leaf litter biomass,branch litter biomass,flower and fruit litter biomass of plant communities in each restoration stage accounted for 64.2%-74.9%,11.4%-18.1%and 9.8%-19.5%of the total litter biomass,respectively.In the early stage of community restoration(sparse tussock,throny shrubland,low shrubland),the monthly dynamics of litter biomass showed a unimodal pattern,while in the middle and later stages of community restoration(other two successional communities),the monthly dynamics of litter biomass showed a bimodal pattern.The monthly dynamics of leaf litter biomass and total litter biomass of plant communities at each restoration stage were basically consistent.The contents of C and N generally showed flower and fruit litter>leaf litter>branch litter.As for plant communities at five different restoration stages,there was a significant positive correlation between the annual total recycling amount of C and N in the litter and their annual total litter biomass.