Microbial communities influence and are influenced by environmental conditions that, together with the extracellular enzymes produced by soil microorganisms, control the rate of decomposition of organic matter in soil. Here, we aim to characterize the interaction of landscape position and depth on potential enzyme activities in a recently burned forest catchment. To accomplish this, we first characterized the heterogeneity of environmental properties, including topography, depth, and soil geochemistry, in order to delineate landscape position and depth controls on potential enzyme activities. To account for the impact of recent wildfire on extracellular enzyme activities (EEA), we delineated surface (0–5 cm) and deeper (5–40 cm) soils to understand how fire (which disproportionally impacts the surface) alters the relationship between EEA and the environmental covariates. We excavated 22 soil pits to 40 cm and measured potential activities of seven hydrolytic enzymes involved in carbon (C) (α-glucosidase [AG], β-1,4-glucosidase [BG], β–D-cellobiohydrolase, [CB] and β-xylosidase [XYL]), nitrogen (N) (β-1,4,N-acetylglucosaminidase, [NAG] and leucine-aminopeptidase [LAP]) and phosphorus (P) acquisition (acid phosphatase [PHOS]) across a subalpine catchment. Fire resulted in decreased BG, CB and NAG activity in surface (0–2 cm) soils. Fire altered N and P acquisition strategies with depth suggesting potential nutrient scavenging or increased internal microbial cycling with depth as a response to fire. Digital soil mapping demonstrated consistently higher potential enzyme activities in the convergent zones of the catchment, which were primarily correlated with higher soil moisture, clay content, and vegetative cover as quantified through normalized difference vegetation index (NDVI). Integrating remotely sensed measures of topography with the identification of drivers of microbial C, N, and P cycling can help inform how millimeter-scale processes influence and feedback to patterns at a catchment scale.

微生物群落影响并受环境条件的影响，环境条件与土壤微生物产生的细胞外酶一起控制土壤中有机物的分解速率。在这里，我们旨在刻画在最近被烧毁的森林流域，景观位置和深度对潜在酶活性的相互作用。为此，我们首先表征了环境特性的异质性，包括地形，深度和土壤地球化学，以描绘潜在酶活性的景观位置和深度控制。为了说明最近的野火对细胞外酶活性（EEA）的影响，我们划定了表面（0-5厘米）和较深（5-40厘米）的土壤，以了解火如何（不成比例地影响地面）如何改变EEA与环境协变量之间的关系。我们在22厘米的土壤坑中开挖了40厘米，并测量了参与碳（C）的7种水解酶的潜在活性（α-葡萄糖苷酶[AG]，β-1,4-葡萄糖苷酶[BG]，β–D-纤维二糖水解酶[CB]和β-木糖苷酶[XYL]），氮（N）（β-1,4，N-乙酰氨基葡糖苷酶，[NAG]和亮氨酸-氨基肽酶[LAP]）和磷（P）的采集（酸性磷酸酶[PHOS]）亚高山流域。火灾导致表层（0–2 cm）土壤中BG，CB和NAG活性降低。火深度改变了氮和磷的获取策略，表明潜在的养分清除或深度增加的内部微生物循环对火的响应。数字土壤测绘表明，汇水区汇聚区的潜在酶活性始终较高，这主要与较高的土壤水分，粘土含量和植物覆盖率相关（如通过归一化植被指数（NDVI）量化）。将遥感地形量度与微生物C，N和P循环驱动因素的识别相结合，可以帮助了解毫米级过程如何影响和反馈集水规模的模式。