阿什河珍珠梅树叶的分解速率与大型底栖动物定殖关系1）

摘要

利用复合分解网袋（上半部为1．0 mm孔径，下半部为0．5 mm孔径）在阿什河上游森林段、中上游农田段和阿什河入松花江口城市段放入珍珠梅树叶，并对其进行了为期77 d的树叶分解研究。结果表明：森林段、农田段和城市段树叶分解速率都为0．02，符合指数衰减模型，均属于快速分解组。不同的河段定殖的底栖动物种类数明显不同，定殖在森林段和农田段大型底栖动物种类分别为25种和15种，二者均以双翅目摇蚊幼虫为主，分别占大型底栖动物类群数的83．6％和70．5％。城市段大型底栖动物种类为6种，全部为寡毛类。从大型底栖动物摄食功能群比例看，森林河段珍珠梅树叶上的大型底栖动物主要以直接集食者为主，占43．7％；其次是撕食者（39．3％）和捕食者（14．4％）。农田河段珍珠梅树叶上大型底栖动物直接集食者比例最高，为77．27％；其次是撕食者为（13．63％）和过滤收集者（4．54％）。城市河段珍珠梅树叶上大型底栖动物全部为直接集食者。结果表明，阿什河上游、中上游和下游中直接集食的底栖动物丰富度与树叶分解速率有显著关系。%The experiment was conducted to study the leaves decomposition rates of Sorbaria sorbifolia with decomposition bags (upper half’s diameter is 1 mm and another half’s diameter is 0.5 mm ) for 77 days in the forest section at the upper rea-ches of the Ashihe River , upstream farmland section and the city section of the River into the Songhua River .The leaf de-composition rates of the forest section , the farmland section and the city section were both 0.02, and the decomposition rate accorded with exponential decay model .Leaves of those sections belonged to the rapid decomposition groups .In the whole experiment process , the species numbers colonization benthic macroinvertebrate of the three sections was obviously differ -ent.The species of benthic fauna in the forest section (25) was higher than that of the farmland section (15), and both belonged to Diptera Chironomus larva, accounting for 83.6%and 70.5%of benthic macroinvertebrates groups , respective-ly.As for the species of the city section , there was six benthic macroinvertebrates classes , all were the little hair class . From functional feeding groups , the gathers/collectors in the forest section was dominant ( 43.7%) , followed by the shred-ders (39.3%) and the predators (14.4%), respectively.While in the farmland section, the gathers/collectors were domi-nant (77.27%), followed by the shredders (13.63%) and the filter collector (4.54%), respectively.There is significant relationship between the abundance of the gathers /collectors and the leaf decomposition rate on summer and fall in the stream of the Ashihe River .