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首页> 外文期刊>Oecologia >Rainfall and labile carbon availability control litter nitrogen dynamics in a tropical dry forest
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Rainfall and labile carbon availability control litter nitrogen dynamics in a tropical dry forest

机译：降雨和不稳定的碳有效性控制了热带干旱森林凋落物氮的动态

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摘要

N cycling in tropical dry forests is driven by rainfall seasonality but the mechanisms involved are not well understood. We studied the seasonal variation in N dynamics and microbial biomass in the surface litter of a tropical dry forest ecosystem in Mexico over a 2-year period. Litter was collected at 4 different times of the year to determine changes in total, soluble, and microbial C and N concentrations. Additionally, litter from each sampling date was incubated under laboratory conditions to determine potential C mineralization rate, net N mineralization, net C and N microbial immobilization, and net nitrification. Litter C concentrations were highest in the early-dry season and lowest in the rainy season, while the seasonal changes in N concentrations varied between years. Litter P was higher in the rainy than in the early-dry season. Water-soluble organic C (WSOC) and water-soluble N concentrations were highest during the early- and late-dry seasons and represented up to 4.1 and 5.9% of the total C and N, respectively. NH4+ and NO3- showed different seasonal and annual variations. They represented an average 23% of soluble N. Microbial C was generally higher in the dry than in the wet seasons, while microbial N was lowest in the late-dry and highest in the early-rainy seasons. Incubations showed that lowest potential C mineralization rates and C and N microbial immobilization occurred in rainy season litter, and were positively correlated to WSOC. Net nitrification was highest in rainy season litter. Our results showed that the seasonal pattern in N dynamics was influenced by rainfall seasonality and labile C availability, and not by microbial biomass. We propose a conceptual model to hypothesize how N dynamics in the litter layer of the Chamela tropical dry forest respond to the seasonal variation in rainfall.
机译：热带干旱森林中的氮循环受降雨季节的影响，但所涉及的机制尚不清楚。我们研究了两年内墨西哥热带干旱森林生态系统表层凋落物中氮动态和微生物生物量的季节性变化。一年中的4个不同时间收集垃圾，以确定总C，N和微生物C和N浓度的变化。另外，将每个采样日期的垃圾在实验室条件下孵育，以确定潜在的C矿化速率，净N矿化，净C和N微生物固定以及净硝化。凋落物C的浓度在早干季节最高，而在雨季最低，而N的季节变化随年份变化。在雨季，凋落物P高于早旱季节。水溶性有机碳（WSOC）和水溶性氮的浓度在旱季的早期和后期最高，分别占总碳和氮的4.1％和5.9％。 NH4 +和NO3-表现出不同的季节和年度变化。它们代表平均23％的可溶性N。在干燥季节，微生物C通常高于在潮湿季节，而在干燥后期，微生物N最低，而在雨季早期则最高。研究表明，在雨季凋落物中，潜在的C矿化率最低，而C和N微生物的固定化最低，并且与WSOC正相关。雨季凋落物的净硝化作用最高。我们的结果表明，氮动态的季节模式受降雨季节和不稳定的碳有效性影响，而不受微生物生物量的影响。我们提出了一个概念模型来假设Chamela热带干旱森林凋落物层中的N动态如何响应降雨的季节性变化。

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