PARENT SESSION
Poster Session #35: Decomposition and Soil Respiration.
Thursday, August 9, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
22
Effects of land use type and disturbance on decomposition in North Carolina.
Barbercheck, Mary1, Neher, Deborah2, El-Allaf, Samia1, Anas, Osama1, 1 2
ABSTRACT- Decomposition of organic matter integrates collective activities of organisms within the soil food web.We compared decomposition of cellulose and balsa wood substrates in 18 sites chosen to represent a factorial combination of three ecosystems (agriculture, wetland, and forest), two disturbance levels, and three land resource regions (LRR) in North Carolina. Decomposition measures were analyzed using repeated measures analysis of covariance with physical soil properties as covariates. Percentage mass remaining and the calculated daily rate of mass loss of cellulose and balsa wood decomposition substrates did not differ among LLR. At the end of the 2-year monitoring period, the percentage of museum board and balsa wood substrates remaining was least in the agricultural and wetland and greatest in the forest ecosystems. Soil pH influenced the percentage of substrate remaining based on days of incubation, and its effects were greater than electrical conductivity, percentage soil organic matter, or total available N. Percentage of substrate remaining (cellulose or balsa wood) was correlated negatively with pH for all sites suggesting that pH should be included as a covariate if measures of decomposition are used as environmental indicators. Overall, the rate of decomposition of cellulose substrates distinguished between relative levels of disturbance in agriculture and wetland but not forest ecosystems. The rate of balsa wood decomposition distinguished between relative levels of disturbance only in wetland sites. Forest soils had consistently lower total N and electrical conductivity, and sometimes lower pH, associated with slower decomposition than in disturbed wetlands or agricultural lands. We conclude that measures of decomposition of cellulose substrates can be used to distinguish between relative levels of disturbance in agricultural and wetland but not forest systems. Differences in rate of decomposition may signal either a change in the decomposer community or condition of biotic and abiotic resources at a site.
KEY WORDS: decomposition, indicators, environmental monitoring, disturbance