Hydrologic losses from tropical forest soils– patterns and implications Lars O. Hedin, Megan McGroddy, Ben Houlton, Emilio Moran and Mateus Battisella LC-09

To determine the biological and physical (climate and geological) controls over patterns of nutrient losses from lowland Amazonian forest ecosystems Justification Carbon cycling is constrained by availability of biologically essential nutrients Goal

DON NO 3 - NH 4 - S TemperateNorth America Hawaii Other Tropical

Approach Extensive sampling Mature or undisturbed forests to determine baseline conditions

denitrification occlusion deposition ground water inputs

Research Approach 1 st phase Determine impact of seasonality on nutrient concentrations and ratios 2 nd phase Extend sampling to include a wider range of sites

1 st phase sites pHCNBasal area Prod. t ha -1 yr -1 N (%) Altamira %0.20 %50nd Santarem %0.17 % % Manaus %0.07% % Soils Leaf litter Altamira data from Moran et al. 2000, Lu et al Santarem data from Silver et al. 2000, Williams et al. 2002, Silver pers. comm. Manaus data from Luizão 1989, Luizão et al 2004

Results Manaus dry Manaus wet Altamira dry Altamira wet Santarem dry Santarem wet Ca (ppm) Altamira Santarem Manaus

Seasalt Cl:Ca ratio

NO 3 - N ppm Altamira Santarem Manaus

Total P ( ppb) Altamira Santarem Manaus

TN:TP ratio Altamira Santarem Manaus

Inorganic N Organic N Altamira Santarem Manaus N concentration (ppm)

wells and lysimeters

Maui Forest Rainfall Gradient

Further goals Expand the sampling gradient in Brasil both in terms of geographic expanse and variability of state factors of interest Incorporate measures of biotic productivity and nutrient demand into analyses Include 15 N and 18 O analyses to determine the importance of denitrification pathways in these sites

Many thanks to: Chico Aves, Jo Bahiano, Niro Higuchi, Flavio Luizao, and the LBA Support Staff in Santarém and Manaus