The impacts of changes in rainfall regimes and atmospheric nitrogen (N) deposition on the biogeochemical cycles of tropical dry forests (TDF) remain unclear. To analyze whether amounts of mean annual rainfall (1240 mm year⁻¹ in subhumid vs. 642 mm year⁻¹ in semiarid forests) and rates of atmospheric N deposition affect the N cycle in TDF, we examined N concentrations in (i) green leaves, (ii) forest floor and mineral soil layers, and (iii) soil microbial biomass, as well as (iv) δ¹⁵N natural abundance in green leaves and (v) rates of soil enzyme activity and (vi) N losses in two sites (one subhumid and another semiarid) of Yucatan. The semiarid site had higher N concentrations in leaves and both soil layers than its subhumid counterpart. Natural abundance δ¹⁵N in the vegetation suggests a more open N cycle with lower rates of rainfall, which was corroborated by N losses as nitrous oxide (N₂O) being twice as high in the semiarid compared to subhumid site. A more open N cycle subject to greater losses in response to N addition in the semiarid site, but not in the subhumid site, reinforce that rainfall amounts strongly affect N cycling in TDF.

降雨制度和大气氮（N）的沉积变化对热带干旱森林（TDF）的生物地球化学循环的影响尚不清楚。为了分析平均年降雨量（半湿润森林中为1240 mm年^-1，半干旱森林中为642 mm年^-1）和大气氮沉降速率是否影响TDF中的氮循环，我们研究了（i）绿叶中的氮浓度，（ⅱ）森林地板和矿质土壤层，以及（iii）微生物生物量，以及（ⅳ）δ ¹⁵ n个自然丰度在绿叶和（v）土壤酶活性和（vi）的速率N的两负尤卡坦州的地点（一个半湿润和另一个半干旱）。与半湿润地区相比，半干旱地区叶片和两个土壤层中的氮含量更高。自然丰度δ植被中的¹⁵ N意味着更开放的N循环，降雨率更低，这是由于N损失所证实的，因为半干旱地区的一氧化二氮（N ₂ O）含量是亚湿润地区的两倍。在半干旱地区（而非在半湿润地区），一个更开放的N循环会因添加N而遭受更大的损失，这加剧了降雨量对TDF中N循环的强烈影响。