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

2. 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

4. 0 200 400 600 800 1000 1200 1400 2000 3000 4000 DON NO 3 - NH 4 - S TemperateNorth America Hawaii Other Tropical

5. Approach Extensive sampling Mature or undisturbed forests to determine baseline conditions

6. denitrification occlusion deposition ground water inputs

7. 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

8. 1 st phase sites pHCNBasal area Prod. t ha -1 yr -1 N (%) Altamira5.21.46%0.20 %50nd Santarem4.22.26 %0.17 %24.45.571.9-2.9% Manaus4.41.0 %0.07%5.421.78% Soils Leaf litter Altamira data from Moran et al. 2000, Lu et al. 2002 Santarem data from Silver et al. 2000, Williams et al. 2002, Silver pers. comm. Manaus data from Luizão 1989, Luizão et al 2004

9. Results Manaus dry Manaus wet Altamira dry Altamira wet Santarem dry Santarem wet 0.01 0.1 1.0 10.0 Ca (ppm) Altamira Santarem Manaus

10. Seasalt Cl:Ca ratio

11. 0.0001 0.001 0.01 0.10 1.00 10.00 NO 3 - N ppm Altamira Santarem Manaus

12. 0.1 1 10 Total P ( ppb) Altamira Santarem Manaus

13. 1 10 100 1000 TN:TP ratio Altamira Santarem Manaus

14. Inorganic N Organic N Altamira Santarem Manaus 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 N concentration (ppm)

15. wells and lysimeters

16. Maui Forest Rainfall Gradient

17. 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

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