Microbial respiration (R_m) and ecoenzyme activities (EEA) related to microbial carbon, nitrogen, and phosphorus acquisition were measured in 792 freshwater and estuarine wetlands (representing a cumulative area of 217,480 km²) across the continental United States as part of the US EPA’s 2011 National Wetland Condition Assessment. EEA stoichiometry was used to construct models for and assess nutrient limitation, carbon use efficiency (CUE), and organic matter decomposition (− k). The wetlands were classified into ten groups based on aggregated ecoregion and wetland type. The wetlands were also assigned to least, intermediate, and most disturbed classes, based on the extent of human influences. Ecoenzyme activity related to C, N and P acquisition, R_m, CUE, and − k differed among ecoregion–wetland types and, with the exception of C acquisition and − k, among disturbance classes. R_m and EEA were positively correlated with soil C, N and P content (r = 0.15–0.64) and stoichiometry (r = 0.15–0.48), and negatively correlated with an index of carbon quality (r = − 0.22 to − 0.39). EEA stoichiometry revealed that wetlands were more often P- than N-limited, and that P-limitation increases with increasing disturbance. Our enzyme-based approach for modeling C, N, and P acquisition, and organic matter decomposition, all rooted in stoichiometric theory, provides a mechanism for modeling resource limitations of microbial metabolism and biogeochemical cycling in wetlands. Given the ease of collecting and analyzing soil EEA and their response to wetland disturbance gradients, enzyme stoichiometry models are a cost-effective tool for monitoring ecosystem responses to resource availability and the environmental drivers of microbial metabolism, including those related to global climate changes.

中文翻译：

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美国本土湿地的微生物生态酶化学计量、营养限制和有机物分解。

在美国大陆的792 个淡水和河口湿地（累计面积为 217,480 km ² ）中测量了与微生物碳、氮和磷获取相关的微生物呼吸 (R _m ) 和生态酶活性 (EEA)。 EPA 2011 年国家湿地状况评估。EEA 化学计量用于构建模型并评估养分限制、碳利用效率 (CUE) 和有机物分解 (−  k )。根据总体生态区和湿地类型将湿地分为十类。根据人类影响的程度，湿地也被分为最少、中等和最受干扰的类别。_{与 C、N 和 P 获取、R m}、CUE 和 −  k相关的生态酶活性在生态区-湿地类型之间存在差异，并且除了 C 获取和 −  k之外，在干扰类别之间也存在差异。R _m和 EEA 与土壤 C、N 和 P 含量 (r = 0.15–0.64) 和化学计量 (r = 0.15–0.48) 呈正相关，与碳质量指数呈负相关 (r = − 0.22 至 − 0.39) 。EEA 化学计量表明，湿地更多地受到 P 限制而不是 N 限制，并且 P 限制随着干扰的增加而增加。我们基于酶的 C、N 和 P 获取以及有机物分解建模方法均植根于化学计量理论，为模拟湿地微生物代谢和生物地球化学循环的资源限制提供了一种机制。鉴于收集和分析土壤 EEA 及其对湿地扰动梯度的响应很容易，酶化学计量模型是一种经济有效的工具，用于监测生态系统对资源可用性和微生物代谢的环境驱动因素（包括与全球气候变化相关的驱动因素）的响应。