Large losses of inorganic nitrogen from tropical rainforests suggest a lack of nitrogen limitation.
Inorganic nitrogen losses from many unpolluted mature tropical forests are over an order of magnitude higher than losses from analogous temperate forests. This pattern could either reflect a lack of N limitation or accelerated plant-soil N cycling under tropical temperatures and moisture. We used a simple analytical framework of the N cycle and compared our predictions with data of N in stream waters of temperate and tropical rainforests. While the pattern could be explained by differences in N limitation, it could not be explained based on up-regulation of the internal N cycle without invoking the unlikely assumption that tropical plants are two to four times less efficient at taking up N than temperate plants. Our results contrast with the idea that a tropical climate promotes and sustains an up-regulated and leaky - but N-limited - internal N cycle. Instead, they are consistent with the notion that many tropical rainforests exist in a state of N saturation.
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA. jbrookshire@montana.edu
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EN
Brookshire
Stefan
S
Gerber
Duncan N L
DN
Menge
Lars O
LO
Hedin
D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D012987:Soil; D013696:Temperature; D014197:Trees / Q000378:metabolism*; D014329:Tropical Climate
D012987:Soil; D009584:Nitrogen