PARENT SESSION
Poster Session #35: Decomposition and Soil Respiration.
Thursday, August 9, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
16
Effects of biodiversity and intrinsic species characteristics on decomposition processes in grasslands.
Vivanco, Lucía1, Austin, Amy 1, 1
ABSTRACT- We studied how intrinsic species characteristics affect rates of decomposition and nutrient release, comparing species from three different grassland ecosystems in North and South America: the Great Plains of the United States; the Patagonian Steppe of Argentina; and the Flooding Pampa of Argentina. All species were grown under constant climatic and nutrient conditions in a greenhouse for one year and senescent litter was collected and placed in decomposition bags in a grassland site in the province of Buenos Aires (1000 mm MAP, 17°C MAT). We collected bags of each species over the course of one year for determination of mass loss and nutrient release. The range of values for decomposition constants (k) was 1.5 to 3.5 years-1 for the fifteen species, with greatest differences between C3 and C4 species (p<0.05). Nitrogen concentration of senescent litter also showed a broad range, from 0.59 to 2.04 %, but was not correlated with rates of mass loss in spite of large differences between %N in C3 versus C4 species (p<0.05). When grouped by site of origin, the three grassland groups had similar ranges of decomposition rates, and precipitation of species origin did not correlate strongly with rates of decomposition. These results suggests that species identity, particularly the functional group identity of C3 versus C4 species, is very important for determining decomposition processes and carbon turnover in grassland ecosystems.
KEY WORDS: decomposition, grasslands, biodiversity, C3 vs C4