Hydrologic nitrogen losses from tropical forest soils -- patterns and implications.
Lars
O
Hedin, Princeton University, lhedin@princeton.edu
Megan
McGroddy, Princeton University, mcgroddy@princeton.edu
(Presenting)
Ben
Houlton, Princeton University, houlton@princeton.edu
Emilio
F.
Moran, Indiana University, moran@indiana.edu
Mateus
Battisella, EMBRAPA Brasilia, mb@cnpm.embrapa.br
Tropical forest soils often tend to be rich in nitrogen but poor in phosphorus. We have measured hydrologic nitrogen and phosphorus losses from soils across a soil fertility gradient in the central Amazon basin. We have found significant differences in both nitrogen and phosphorus species and concentrations at regional scales. When considered in combination with data on nutrient concentrations and 15N stable isotopes from other tropical forests worldwide, these data support the idea that tropical soils develop nitrogen sufficiency over time. We will discuss the paradoxical nature of mechanisms needed to support this apparent pattern.