Ecosystem Consequences of Tree Monodominance for Nitrogen Cycling in Lowland Tropical Forest

摘要: Understanding how plant functional traits shape nutrient limitation and cycling on land is a major challenge in ecology. This especially true for lowland forest ecosystems of the tropics which can be taxonomically functionally diverse rich bioavailable nitrogen (N). In many tropical regions, however, forests occur side-by-side with monodominant (one species >60% canopy); long-term biogeochemical consequences tree monodominance are unclear. Particularly uncertain whether plant-soil system modifies balance at ecosystem level. Here, we use chemical stable isotope techniques to examine N old-growth Mora excelsa watershed rainforests island Trinidad. Across 26 small 4 years, show that reduces nitrate exceedingly low levels which, turn, results hydrologic gaseous losses watershed-level relative adjacent N-rich forests. Bioavailable soils streams remained remarkably through time forests; forests, other hand, showed high sensitivity seasonal inter-annual rainfall variation. Total mineral from exceeded inputs atmospheric deposition, consistent saturation, while did not, suggesting limitation. Our measures suggest this difference cannot explained by environmental factors but instead internal production efficient retention system. These demonstrate ecosystem-level cycle opposite cases where trees enhance supply via N2 fixation that, over time, may generate progressive draw-down