模拟放牧采食对典型草原土壤中AM真菌分解枯落物的影响

丛枝菌根真菌(Arbuscular mycorrhizal fungi, AMF)在陆地生态系统中分布广泛,不仅可以促进宿主植物生长发育,还会参与枯落物的降解,间接影响土壤碳库。本研究使用典型草原优势种羊草(Leymus chinensis)做枯落物,通过适宜孔径尼龙网分离AMF根外菌丝与土壤中其他微生物,探究植物功能群和刈割处理对AMF参与枯落物分解的影响。结果表明AMF通过提升土壤中β-葡糖苷酶和多酚氧化酶的活性加速对枯落物的降解。植物功能群的改变会影响枯落物分解,其中杂类草处理中枯落物分解率较高(2016年：31.72%;2017年：31.02%),C₄禾草处理中的最低(2016年：23.22%;2017年：27.10%);但并不会改变AMF对枯落物的分解作用。刈割在短时间内对枯落物的分解无显著影响。本研究发现AMF促进了枯落物分解,植物群落组成的改变也会显著影响枯落物的分解。

Responses of Arbuscular Mycorrhizal Fungi (AMF) in Litter Decomposition to the Simulated Grazing in Typical Steppe

Arbuscular mycorrhizal (AM) fungi can develop mutualistic symbiosis with plants across the world. AMF promote plant growth and influence litter decomposition process which may subsequently alter soil carbon sequestration. To test the effect of plant functional group and mowing on mycorrhizal contribution to litter decomposition,we used nylon meshes that did allow or exclude AMF hyphe. Our results show that the presence of AM fungi facilitated the activates of soil β-glucosidase and polyphenol oxidase in a result of accelerating the degradation of litter. In addition,litter decomposition rate of the forb group was higher than that of other groups (2016:31.72%,2017:31.02%),and the lowest decomposition rate was occurred at the C₄ grass group (2016:23.22%,2017:27.10%). There was no influence of plant functional group on mycorrhizal contribution to litter decomposition. Mowing would have no effect on the contribution of AM fungi to litter decomposition probably because of the early stage of that disturbance. Our results indicate that the presence of AM fungi may facilitate the degradation of litter,and changes in plant community composition may alter the rate of litter decomposition.