Soil enzymes produced by microorganisms transform substrates in the soil carbon (C) and nutrient cycles. Limitations in C and other nutrients could affect microbial biosynthesis processes, so we expect that soil enzyme activity will reflect microbial deficiencies in C, nitrogen (N) and phosphorus (P) at a large spatial scale. We collected soil from nutrient addition trials in eight forest ecosystems, ranging from temperate forests to tropical forests in eastern China, and conducted vector analysis of the soil enzymatic stoichiometry to examine the spatial extent of soil microbial C and nutrient limitations. We also determined whether nutrient addition could alleviate nutrient limitation or otherwise impact soil microbial resource use. Soil microbial C vs. nutrient limitation (thereafter C limitation) was greater in the temperate forests than in the tropical forests, but did not vary with soil depth. Soil microbial P vs. N limitation (thereafter nutrient limitation) decreased with latitude, and increased with soil depth. We found a negative relationship between soil microbial C limitation and nutrient limitation, which was more pronounced in the topsoil than in deeper soil depths. Furthermore, we found that climate (mean annual precipitation and temperature), soil pH and soil nutrients were significantly correlated with soil microbial C (explaining about 23% of the variation) and nutrient limitation (responsible for about 87% of the variation). Nutrient addition represented ~1% of the variation in soil microbial C and nutrient limitations and thus did not alleviate nutrient deficiencies. We conclude that soil microbial C and nutrient limitations are more likely driven by climate and soil physicochemical properties than by nutrient addition in eight forest ecosystems. Since soil microbial C and nutrient limitations result from long-term adaptation of soil microbial communities to site-specific soil and environmental conditions, the soil enzyme activity is not modified by short-term changes in nutrient availability resulting from fertilizer application.

微生物产生的土壤酶会转化土壤碳（C）和养分循环中的底物。碳和其他养分的限制可能会影响微生物的生物合成过程，因此我们预计土壤酶活性将在较大的空间范围内反映碳，氮（N）和磷（P）的微生物缺乏。我们从八种森林生态系统（从温带森林到热带森林）的养分添加试验中收集了土壤，并对土壤酶化学计量进行了矢量分析，以检查土壤微生物碳的空间范围和养分限制。我们还确定了添加养分是否可以减轻养分限制或以其他方式影响土壤微生物资源的使用。土壤微生物碳与 温带森林的养分限制（此后为C限制）大于热带森林，但不随土壤深度变化。土壤微生物对氮和磷的限制（其后为养分限制）随纬度而降低，随土壤深度而增加。我们发现土壤微生物碳限制与养分限制之间存在负相关关系，在表土中比在更深的土壤深度中更明显。此外，我们发现气候（平均年降水量和温度），土壤pH值和土壤养分与土壤微生物C（解释约23％的变化）和养分限制（约占87％的变化）显着相关。营养添加量约占土壤微生物C和养分限制变化的1％，因此不能缓解养分缺乏。我们得出结论，在八个森林生态系统中，土壤微生物的碳和养分限制更可能由气候和土壤理化特性驱动，而不是由养分添加引起。由于土壤微生物碳和养分的限制是由于土壤微生物群落长期适应特定地点的土壤和环境条件而引起的，因此土壤酶活性不会因施肥导致的养分可利用性的短期变化而改变。