马尾松人工林郁闭度对大型土壤动物功能群的影响

Effects of canopy density on the functional group of soil macro fauna in Pinus massoniana plantations

将土壤动物分为捕食性、腐食性、杂食性、食木性和菌食性5个功能群,研究马尾松人工林各功能群大型土壤动物随郁闭度(0.5、0.6、0.7、0.8、0.9)的变化.结果表明:1)各郁闭度马尾松人工林大型土壤动物以腐食性个体比例最高,类群上以杂食性和食木性为主.2)马尾松人工林大型捕食性土壤动物个体数、类群数和食木性类群数在0.5~0.6郁闭度下无显著变化,在0.6~0.9郁闭度下显著降低.3)随郁闭度增大,枯落物层捕食性土壤动物个体和类群数显著减少,5~10 cm层腐食性土壤动物个体数呈不规则的波动变化.食木性土壤动物个体数随土层加深而增多,且在枯落层其类群数及5~10 cm层个体和类群数随郁闭度增大而显著减少.4)不同郁闭度下,除食木性土壤动物功能群Pielou均匀度无显著差异外,食木性和腐食性土壤动物各多样性指标均差异显著;捕食性土壤动物仅Simpson优势度指数在0.5~0.8郁闭度下无显著变化,在0.8~0.9郁闭度下显著降低.5)典范对应分析(CCA)显示,不同郁闭度马尾松人工林大型土壤动物功能群主要受土壤容重和含水量的影响.含水量对腐食性土壤动物个体数影响较大,食木性、捕食性土壤动物受土壤容重影响,捕食性土壤动物Simpson优势度指数受土壤pH和全磷影响.大型土壤动物功能群结构在0.7郁闭度下相对稳定,有利于马尾松人工林地力维持和生态功能的发挥.

in order to understand the effects of canopy density on the functional group characteris- tics of soil rnacrofauna in Pintts massoniana plantations, we divided the captured soil fauna into five types including xylophages, predators, saprophages, omnivores and fungal feeders. The results showed that 1 ） Saprozoic feeders had the highest percentage of total individuals, and the omnivores and xylophages occupied higher percentages of total taxa. 2） The individual and group number of the predators, and the group number of xylophages did not change significantly under 0.5-0.6 and then decreased significantly under 0.6-0.9 canopy density. 3） With the increasing canopy density, the individual an dgroup number of predators in litter layer decreased significantly, the saprozoic individual number in 5-10 cm soil layer represented irregular trends. The individual number of xy- lophage increased with the depth of soil, and the group number in litter layer, the individual and group number in 5-10 cm soil layer decreased significantly. 4） Pielou evenness of xylophage had no significant changes with the canopy density, all the other diversity index of xylophage and saproph- age were various with the increasing canopy density. The predatory Simpson index was stable under 0.5-0.8, and then decreased significantly under 0.8-0.9 canopy density. 5） The CCA （canonical correlation analysis） indicated that soil bulk density and moisture content were the main environ-mental factors affecting functional groups of soil macro fauna. Moisture content greatly impacted on the number of saprophagous individuals. But xylophage and predators were mostly affected by soil bulk density, and the predatory Simpson index was mainly affected by soil pH value and total phos- phorus. Our research indicated that the structure of soil macro faunal functional group under 0.7 canopy density was comparatively stable, which would facilitate the maintenance of soil fertility and ecological function in Pinus massoniana plantation.