米槠人工林土壤微生物群落组成对凋落物输入的响应

全球气候变化显著影响森林凋落物数量,进而会对土壤微生物群落造成影响。本研究以亚热带米槠人工林为研究对象,探究不同凋落物量输入处理(凋落物去除、凋落物加倍、对照)下,森林土壤微生物群落组成的变化。结果表明:与去除凋落物相比,凋落物加倍后0~10 cm土壤铵态氮(NH4^+-N)、硝态氮(NO3^--N)、全氮(TN)、有效磷(AP)含量分别显著增加了30.30%、49.66%、12.77%和13.90%。与对照相比,凋落物加倍与去除处理土壤微生物生物量碳(MBC)和氮(MBN)含量分别显著增加和下降(P<0.05),但凋落物加倍与去除处理间无显著差异。凋落物加倍处理下土壤丛枝菌根真菌(AMF)、革兰氏阳性菌[G(+)]、革兰氏阴性菌[G(-)]、放线菌(ACT)、真菌(F)丰度和总磷脂脂肪酸(TPLFA)含量分别比去除凋落物处理的土壤高68.35%、63.35%、82.65%、69.02%、40.56%和65.85%,而土壤革兰氏阳性菌与阴性菌比值、真菌与细菌比值则分别降低11.64%和26.67%。冗余度分析表明,铵态氮是影响该人工林土壤微生物群落组成的最主要环境因子。可见凋落物输入量变化改变了土壤养分有效性,进而显著影响了土壤微生物群落组成,这对进一步深入探究全球气候变化对亚热带森林土壤养分循环的影响具有重要意义。

Response of soil microbial community composition on litterfall input in a Castanopsis carlesii plantation

Global climate change will affect the amounts of forest littersfall,and then affect the biogeochemical cycle of soil.In this study,soil microbial community composition under different litter input treatments(no litter,double litter,control)were measured in a subtropical Castanopsis carlesii plantation.The results showed that the content of soil ammonium nitrogen,nitrate nitrogen,total nitrogen and available phosphorus in double litter treatment were 30.30%,49.66%,12.77% and 13.90% higher than those in no litter treatment,respectively.Compared with the control,soil microbial biomass carbon(MBC)and nitrogen(MBN)contents in double litter treatment increased significantly while decreased in the litter removal treatment.There was no significant difference in soil MBC and MBN between double litter and litter removal treatments.The abundance of arbuscular mycorrhizal fungi,G(+)bacteria and G(-)bacteria,actinomyces,and fungi as well as total phospholipid fatty acid content in double litter treatment were 68.35%,63.35%,82.65%,69.02%,40.56%and 65.85%higher than those in litter removal treatment,respectively,while the ratio of gram positive bacteria to negative bacteria and fungi to bacteria were 11.64%and 26.67% lower than those in litter removal treatment.Redundancy analysis showed that ammonium nitrogen and pH value were the most important environmental factors affecting the composition of soil microbial community in the plantation.Different litter input changed soil nutrient availability,and then significantly affected the soil microbial community composition.It is of great significance for further understanding of global climate change effects on soil nutrient cycling in subtropical forests.