土壤碳(C)、氮(N)、磷(P)化学计量特征会显著影响微生物的生长、群落结构、生物量C:N:P化学计量及其代谢活动。然而生态系统演替过程中土壤-微生物C:N:P化学计量的时间格局及其协调关系还不明确。为此, 该研究收集了2016年5月以前发表的文献中19个生态系统演替序列(包括13个森林、6个草地生态系统)的土壤-微生物生物量C:N:P研究结果, 整合分析了其中土壤-微生物生态化学计量的时间动态, 结果表明: (1)生态系统演替过程中土壤C:N没有一致的时间格局, 而土壤C:P和N:P均随演替进程显著增加, 其中土壤C:N:P与演替时间之间线性关系的斜率与相应演替序列的初始土壤有机C含量呈负相关关系。(2)演替进程中土壤-微生物生物量C:N:P没有一致的时间格局。(3)微生物生物量C占土壤有机C百分比(qMBC)、微生物生物量N占土壤全N百分比、微生物生物量P占土壤全P百分比均随着演替进程而显著增加, 即单位资源所能支持的微生物生物量随着演替进程而增加, 这与宏观生态系统演替理论相符。(4) qMBC随着土壤C:N、C:P和N:P以及C:N、C:P和N:P化学计量不平衡性(即土壤C:N、C:P和N:P分别除以微生物生物量C:N、C:P和N:P)的增加而减小; 其中, C:N、C:P和N:P化学计量不平衡性解释了qMBC变异性的37%-57%, 是演替时间解释率的7-17倍, 表明土壤-微生物生态化学计量关系对qMBC演替动态有重要影响。该研究强调了生态化学计量学理论和生态系统演替理论在土壤微生物时间动态研究中的重要作用, 表明适当地融合生态学宏观理论于土壤微生物研究可以加深对土壤-微生物生态过程的认识。

AimsThe carbon (C), nitrogen (N) and phosphorus (P) stoichiometry (C:N:P) of soil profoundly influences the growth, community structure, biomass C:N:P stoichiometry, and metabolism in microbes. However, the relationships between soil and microbes in the C:N:P stoichiometry and their temporal dynamics during ecosystem succession are poorly understood. The aim of this study was to determine the temporal patterns of soil and microbial C:N:P stoichiometry and their relationships during ecosystem succession.MethodsAn extensive literature search was conducted and data were compiled for 19 age sequences of successional ecosystems, including 13 forest ecosystems and 6 grassland ecosystems, from 18 studies published up to May 2016. Meta-analyses were performed to examine the sequential changes in 18 variables that were associated with soil and microbial C, N and P contents and the stoichiometry. Important findings (1) There was no consistent temporal pattern in soil C:N along the successional stages, whereas the soil C:P and N:P increased with succession; the slopes of the linear relationships between soil C:N:P stoichiometry and successional age were negatively correlated with the initial content of the soil organic C within given chronosequence. (2) There was no consistent temporal pattern in microbial C:N:P stoichiometry along the successional stages. (3) The fraction of microbial biomass C in soil organic C (qMBC), the fraction of microbial biomass N in soil total N, and the fraction of microbial biomass P in soil total P all increased significantly with succession, in consistency with the theory of succession that ecosystem biomass per unit resource increases with succession. (4) The qMBC decreased with increases in the values of soil C:N, C:P, or N:P, as well as the stoichiometric imbalances in C:N, C:P, and N:P between soil and microbes (i.e., ratios of soil C:N, C:P, and N:P to microbial biomass C:N, C:P, and N:P, respectively). The C:N, C:P, and N:P stoichiometric imbalances explained 37%-57% variations in the qMBC, about 7-17 times more than that explainable by the successional age, illustrating the importance of soil-microbial C:N:P stoichiometry in shaping the successional dynamics in qMBC. In summary, our study highlights the importance of the theories of ecosystem succession and stoichiometry in soil microbial studies, and suggests that appropriately applying macro-ecological theories in microbial studies may improve our understanding on microbial ecological processes.