Extracellular enzymes (EE) play a vital role in soil nutrient cycling and thus affect terrestrial ecosystem functioning. Yet the drivers that regulate microbial activity, and therefore EE activity, remain under debate. In this study we investigate the temporal variation of soil EE in a tropical terra-firme forest. We found that EE activity peaked during the drier season in association with increased leaf litterfall, which was also reflected in negative relationships between EE activities and precipitation. Soil nutrients were weakly related to EE activities, although extractable N was related to EE activities in the top 5 cm of the soil. These results suggest that soil EE activity is synchronized with precipitation-driven substrate inputs and depends on the availability of N. Our results further indicate high investments in P acquisition, with a higher microbial N demand in the month before the onset of the drier season, shifting to higher P demand towards the end of the drier season. These seasonal fluctuations in the potential acquisition of essential resources imply dynamic shifts in microbial activity in coordination with climate seasonality and resource limitation of central-eastern Amazon forests.

细胞外酶 (EE) 在土壤养分循环中起着至关重要的作用，从而影响陆地生态系统的功能。然而，调节微生物活动以及 EE 活动的驱动因素仍存在争议。在这项研究中，我们调查了热带陆地森林中土壤能效的时间变化。我们发现 EE 活动在较干燥的季节达到顶峰，与落叶量增加有关，这也反映在 EE 活动与降水之间的负相关中。土壤养分与 EE 活动弱相关，尽管可提取 N 与土壤表层 5 cm 的 EE 活动相关。这些结果表明，土壤 EE 活动与降水驱动的底物输入同步，并取决于 N 的可用性。我们的结果进一步表明对 P 获取的高投资，在干旱季节开始前一个月微生物 N 需求较高，在干旱季节结束时转向较高的 P 需求。这些潜在获取基本资源的季节性波动意味着微生物活动的动态变化与亚马逊中东部森林的气候季节性和资源限制相协调。