Effects of disturbance and ecosystem on decomposition

Abstract

Decomposition of organic matter integrates collective activities of organisms within the soil food web. We compared decomposition of museum board (predominantly cellulose) and balsa wood substrates in 18 sites chosen to represent a completely nested design with two disturbance levels nested within three ecosystems (agriculture, wetland, and forest) and ecosystems nested within three land resource regions (LRR) in North Carolina. Percentage mass remaining and daily rate of mass loss of museum board and balsa wood substrates were analyzed using repeated measures analysis of covariance with soil physical and chemical properties as covariates. At the end of the two-year monitoring period, the percentage of museum board and balsa wood substrates remaining was least in agricultural and wetland and greatest in 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, and total available soil nitrogen (N). Percentage of substrate remaining (museum board 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, rate of decomposition of museum board substrates distinguished between relative levels of disturbance in agricultural and wetland but not forest ecosystems. The rate of balsa wood decomposition distinguished between relative levels of disturbance in wetland but not forest or agricultural sites. Forest soils had consistently lower total N and electrical conductivity, and sometimes lower pH, associated with slower decomposition than disturbed wetlands or agricultural lands. We conclude that for short-term monitoring, measures of decomposition of predominantly cellulose substrates can be used to distinguish between relative levels of disturbance in agricultural and wetland but not forest systems. Differences in decomposition may signal either a change in decomposer community or condition of biotic and abiotic resources at a site.

Soil invertebrate and microbial communities, and decomposition as indicators of polycyclic aromatic hydrocarbon contamination

“…Decomposition reflects changes in microbial and invertebrate populations and communities. Generally, decomposition rate at the study site (cellulose 0.24-0.69% loss/day; lignin/cellulose mixture 0.19-0.62% loss/day) were slower than in other studies measured either with litter baskets (Neher et al, 2002) or litter bags in other temperate deciduous forest soils. For example, cellulose degraded 36.3% and lignin 8.1% within 12 weeks (Entry and Backman, 1995) compared to 31.0 and 41.7% total mass loss of cellulose and lignin/cellulose (initially 22% lignin, 76% cellulose), respectively, during our study of 15 weeks.…”

Aboveground decomposition dynamics in riparian depression and slope wetlands of central Pennsylvania

“…Using cellulose strips in humus layers, Kurka et al (2001) found cation exchange capacity to positively correlate with decomposition. Neher et al (2003) also found there was a trend for the percentage of soil organic matter to positively correlate with decomposition. High organic matter often correlates with high cation exchange capacity as organic matter colloids have large quantities of negative charges.…”

Soil microbiological properties during decomposition of crop residues under conventional and zero tillage

“…This is in agreement with the correlations that were observed between residue quality and microbiological characteristics (discussed in the preceding paragraph). Decomposition is a useful indicator of soil condition because it integrates the collective activities of soil organisms involved in the soil food web (Neher et al 2003). Therefore, soil microorganisms play key roles in sustaining the fertility and productivity of agricultural soils.…”