表土和底土中微生物残体对增温的差异性响应OA

[Objective]Microbial necromass carbon(MNC)is an important component of the soil organic carbon(SOC)pool and probing the response of MNC to climate change is key to a deeper understanding of the mechanisms of microbial-mediated regulation of SOC formation.There is still a lack of understanding regarding the impact of climate warming on topsoil and subsoil MNC accumulation dynamics in different ecosystems.[Method]A meta-analysis was conducted to investigate the effect of warming of 8 sample sites on MNC in different soil layers and its contribution to SOC and on the response of topsoil and subsoil MNC to warming(41 for total amino sugars,69 for glucosamine,69 for muramic acid and 26 for galactosamine).[Result]Warming promoted the accumulation of MNC in different soil layers as a whole,especially in the topsoil(14.3%).This may be related to the differences in plant-carbon input and the spatial heterogeneity of microbial communities in different soil layers under a warming background.However,due to the acceleration of the loss of SOC in the subsoil after warming,the proportion of MNC contribution to SOC in the subsoil(12.5%)was higher than that in the topsoil(11.3%).Furthermore,the positive effect of the accumulation of fungal necromass and their contribution to SOC in different soil layers was greater than that of bacterial necromass,suggesting that the new carbon imput directly or indirectly regulat the composition of MNC.Moreover,the impact of warming on the accumulation of MNC in different soil layers is bound up with warming amplitude and years.Lower warming(≤2℃)promoted microbial anabolism to increase the accumulation of MNC in the topsoil by 17.2%,while the contribution of MNC in increasing SOC in the subsoil pool was significantly promoted(14.7%)during higher warming(>2℃).On the timescale of warming,long-term warming(>5 a)changed the microbial activity pattern and had a greater impact on the ratio of MNC to SOC in subsoil(42.8%).Meanwhile,the contribution of microbial necromass to SOC was increased with soil depth in forest and cropland,whereas warming weakened the proportion of subsoil microbial necromass to SOC in grassland.[Conclusion]Based on our analysis,it is suggested that future research on the dynamics of microbial-mediated organic carbon accumulation in specific ecosystems in response to warming should focus on the response of microbial necromass in both topsoil and subsoils.This would provide a huge boost to understanding and predicting the sensitivity of SOC dynamics to climate change and its feedback mechanisms.