土壤线虫群落对森林凋落物分解主场效应的作用

Effect of soil nematode communities on the home-field advantage of forest litter decomposition

以大连西郊国家森林公园作为样地,以黑松和辽东栎两种叶凋落物作为分解基质,采用两种不同网孔的凋落物袋法,从土壤线虫群落组成、凋落物分解速率、凋落物养分释放、土壤线虫群落多样性及其与凋落物理化指标的相关性等几个方面来探究森林凋落物分解的主场效应及土壤线虫群落的作用。结果表明:研究期间共鉴定出4570条土壤线虫,隶属于35个属。0.1mm网袋中共鉴定4407条线虫,远高于0.02mm网袋的163条;而0.02mm网袋控制了土壤线虫参与凋落物分解,可视为仅由微生物参与分解过程。凋落物在主场与客场分解损失率差值(Ph-Pa、Qh-Qa)、元素残留率差值(Pa-Ph、Qa-Qh)总体呈增加趋势,说明土壤线虫对主场凋落物分解作用明显。凋落物质量损失和C、N释放量表现为0.1mm网袋>0.02mm网袋,主场>客场,主场与客场存在一定差异,表明土壤线虫促进了凋落物分解,且对主场凋落物分解贡献较大。主场线虫数量和种类较多,调控着微生物的群落结构及活动,进而加速了凋落物分解和养分释放,同时主场效应又决定着凋落物的分解速率和养分释放。研究结果可为今后森林凋落物分解的相关研究中主场效应、客场效应以及土壤生物驱动效应研究提供参考。

This study expounded the effect of soil nematode communities on the home-field advantage of the leaf litter decomposition of Pinus thunbergii Parl and Quercus liaotungensis Koidz, using litterbags with different mesh sizes in Dalian National Forest Park, China. We analyzed the soil nematode community composition, diversity and distribution, litter decomposition rate, and nutrient release. Furthermore, we studied a correlation between the number of nematodes, number of genera, ecological indices, and litter physico-chemical properties. The results showed that a total of 4570 nematodes belonging to 35 genera were collected. The number of nematodes collected in 0.1-mm litter bags （4407） was significantly more than that of the nematodes collected in 0.02-mm litter bags （163）. Litter decomposition was driven by soil nematodes and microorganisms in the treatment with 0.1-mm litter bags. However, soil nematodes were controlled by 0.02-mm litter bags; therefore, soil nematodes were regarded as the only microorganisms involved in litter decomposition. An increase was observed in the difference of litter loss rate and element residual rate between home and away. It showed that soil nematodes had an obvious effect on the home-field litter decomposition. Litter mass loss rate and C ,N release quantity in 0.1-mm litter bags were more than that in 0.02-mm litter bags. Litter mass loss rate and C,N release quantity in the home environment were more than that in the away environment. Some differences in the environment of home and away showed that soil nematodes promoted litter decomposition and significantly contributed to home-field. In the home environment, soil nematodes showed a high degree of community richness, regulated and controlled community structure and edaphon activity, and further accelerated litter decomposition and nutrient release. Meanwhile, the home-field advantage also determined litter decomposition rate and nutrient release. These results will provide a reference for the home-field and away-field advantage of litter decomposition and for the soil organism-driven effect on the forest litter decomposition in a related study in the future.