两种树叶在华南地区贫营养型池塘中的分解速率研究

在热带亚热带地区，凋落物在湖泊、湿地中的分解过程知之甚少。为了解亚热带地区树叶凋落物在静水环境中的分解状况，利用分解网袋法对2种树叶（大叶相思和人心果）在广州长岗山自然保护小区一贫营养型池塘中进行了为期130d的树叶分解研究。结果显示，两种树叶在池塘中的分解速度非常缓慢，130d后大叶相思和人心果树叶的干重剩余率分别为74.3％和77．5％，经指数衰减模型拟合，两者的分解速率系数（k）分别为0．00145d^-1和0．00105d^-1。定殖在两种树叶上的大型底栖动物仅5种，其中优势类群为摇蚊幼虫和钩虾。结果表明寡营养型池塘中大型底栖动物功能摄食群中撕食者种类与数量的稀少是引起这两种树叶分解缓慢的主要因素之一。

Decomposition rates of two species of leaf fitter at an oligotrophic pond in the southern China

The litter breakdown in lake and wetland is poor known in tropical and subtropical regions. To investigate the decomposition of leaf litter in lentic environment of subtropical region,breakdown rates of ear-leaved acacia (Acacia auriculaeformis) and sapodilla (Manilkara zapoto) leaves were measured over a 130-day period using coarse-mesh bags in an oligotrophic pond at the Changgangshan Nature Reserve,Guangzhou. The results showed that the decomposition rates of these two leaf species were quite slow. After 130 days,ear-leaved acacia leaves and sapodilla leaves lost 25.7% and 22.5% of their initial mass only. The daily breakdown coefficients (k) of A. auriculaeformis and M. zapoto were respectively 0.00145 d-1 and 0.00105 d-1 which fitted well by an exponential decay model. The macroinvertebrates colonized on two leaf species were only five species,of which Chironomus sp. and Gammarus sp. were dominant benthos. The results suggest that the scarcity of shredders is one of main factors which make the breakdown rates of these two species much slower.