Reviews and syntheses: Soil resources and climate jointly drive variations in microbial biomass carbon and nitrogen in China's forest ecosystems

[摘要] Microbial metabolism plays a key role in regulating the biogeochemical cycleof forest ecosystems, but the mechanisms driving microbial growth are notwell understood. Here, we synthesized 689 measurements on soil microbialbiomass carbon (C_mic) and nitrogen (N_mic) and related parametersfrom 207 independent studies published up to November 2014 across China'sforest ecosystems. Our objectives were to (1) examine patterns inC_mic, N_mic, and microbial quotient (i.e., C_mic / C_soil andN_mic / N_soil rates) by climate zones and management regimes forthese forests; and (2) identify the factors driving the variability in theC_mic, N_mic, and microbial quotient. There was a large variability inC_mic (390.2 mg kg⁻¹), N_mic (60.1 mg kg⁻¹,C_mic : N_mic ratio (8.25), C_mic / C_soil rate (1.92 %), andN_mic / N_soil rate (3.43 %) across China's forests. The naturalforests had significantly greater C_mic (514.1 mg kg⁻¹vs. 281.8 mg kg⁻¹) and N_mic (82.6 mg kg⁻¹ vs. 39.0 mg kg⁻¹) than theplanted forests, but had less C_mic : N_mic ratio (7.3 vs. 9.2) andC_mic / C_soil rate (1.7 % vs. 2.1 %). Soil resources and climatetogether explained 24.4–40.7 % of these variations. TheC_mic : N_mic ratio declined slightly with C_soil : N_soil ratio,and changed with latitude, mean annual temperature and precipitation,suggesting a plasticity of microbial carbon-nitrogen stoichiometry. TheC_mic / C_soil rate decreased with C_soil : N_soil ratio,whereas the N_mic / N_soil rate increased with C_soil : N_soil ratio; the former was influenced more by soil resources than by climate,whereas the latter was influenced more by climate. These results suggestthat soil microbial assimilation of carbon and nitrogen are jointly drivenby soil resources and climate, but may be regulated by different mechanisms.

[学科分类] 地球化学与岩石