贵州喀斯特生态系统不同恢复阶段凋落物及碳氮归还动态

凋落物是森林生态系统碳库重要组成部分,通过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)植物群落凋落物总量、凋落物组成(叶、枝、花果等)特征、凋落物月动态及碳氮归还量进行了一年的定位观测。结果显示,正向演替的各群落年凋落量分别为726.0、3811.6、5161.0、4378.8和4604.8kg.hm-²；随着群落演替发展,各群落凋落物总量呈现出先升高后缓降。其中凋落叶量占凋落总量的64.2%~74.9%,凋落枝量占总凋落物的11.4%~18.1%,花果等凋落量占9.8%~19.5%,花果等凋落量与群落演替阶段显著正相关。群落演替初期凋落量月动态呈单峰型,而群落演替中后期凋落量月动态呈双峰型；各演替群落的叶凋落物与总凋落物的月动态基本一致。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种演替群落总凋落物C、N的年归还总量与其年凋落总量显著正相关。

Dynamics of Litterfall and carbon and nitrogen recycling of different successional communities in Karst area of Puding, Guizhou Province, China. XIONG Hong-fu1,

(1.School of Material and Chemical Engineering, Tongren University;Tongren 554300,Guizhou,China;) : Litterfall is an important composition of carbon budget and material cycling in terrestrial ecosystems. Litterfall biomass, its components (leaves, branches, flowers and fruits) ,monthly dynamics and carbon and nitrogen recycling in five different successional communities (sparse tussock, throny shrubland, low shrubland, shrubby woodland and forest, secondary mixed evergreen and deciduous broadleaved forest ) were studied in Karst area of Puding, central Guizhou Province, China. Results show that the averaged annual litterfall biomass of above five different successional communities were 726.0、3811.6、5161.0、4378.8 and 4604.8 kg.hm-², respectively. During the forward successional process, litterfall increased during the initial stage, then gradually decreased in medium stage. Litterfall of each components, the leaf, branch, flower and fruit accounted 64.2%~74.9%,11.4%~18.1%, and 9.8%~19.5% of the total litterfall, respectively. The flowers and fruits litterfall showed a consistent monthly dynamic with the total litterfall. The monthly litterfall dynamics of sparse tussock, throny shrubland, low and shrubland exhibited a unimodal distribution, while other two successional communities exhibited a bimodel distribution.The content of C and N generally showed flower and fruit litterfall > leaf litterfall > branch litterfall. The total annual return of litterfall of C and N in the six successional communities was significantly positively correlated with the total annual litterfall.