PARENT SESSION
Oral Session 3: Biogeochemistry I: Litter and Decomposition.
Presiding: J Dilustro
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room A 107.
The influence of litter production on P cycling in a wet tropical rain forest.
Wood, Tana*,1, Lawrence, Deborah1, Clark, Deborah2, 1 Department of Environmental Science, Charlottesville, VA, USA2 University of Missouri, St. Louis, MO
ABSTRACT- The study of leaf litter nutrient cycling could provide important information on the response of wet tropical forests to both land use and environmental change. The goal of our research was to assess whether (1) leaf litter nutrient cycling responds to variation in the quantity and quality of litterfall, and (2) to determine how forest age and soil fertility influence this response. In July 2001, we established a litter manipulation experiment in secondary and mature forests of varying soil fertility at La Selva Biological Station, Costa Rica. Leaves and twigs <2cm in diameter were removed from a 400m2 area and added to an adjacent area of 100m2. This transfer was equivalent to adding 100-200g of phosphorus (P) per m2 and approximately doubled the annual organic matter input to the forest floor. We established two replicates of the removal and addition treatments, plus a control plot at each of six locations (2 secondary, 2 mature-high fertility, 2 mature-low fertility). We analyzed leaf litter production and P concentration in the three treatments (addition, control, removal) over a 2-yr period. Overall, litter addition resulted in a significant increase in the amount of leaf litterfall during the 6mo period immediately following litter addition (RANOVA treatment effect; df=2, F=13.05, p=0.002). Additionally, 6 mo after litter addition, the total P input was 50-80% higher in addition plots than in either the control or the removal plots. Although the magnitude of both leaf litterfall and P input was greater in the addition plots than in the control and removal plots, the temporal pattern did not differ among the three treatments. Hence, temporal variability in leaf litterfall and P content is likely driven by a common environmental factor. Our results indicate that both the quality and quantity of leaf litterfall feed back positively on leaf litter nutrient cycling.
Key words: P, nutrient cycling, Litter, tropical forest