Wood Decomposition Rates Research Articles

Effects of disturbance and ecosystem on decomposition

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.

Respiration from coarse woody debris as affected by moisture and saprotroph functional diversity in Western Oregon.

Decomposing coarse woody debris (CWD) is a conspicuous and important component of forest ecosystems. Seasonal temperature and precipitation patterns influence heterotroph activity, which determines the rate of CWD decomposition. We tested the hypothesis that moisture content and heterotroph community composition influence carbon flux in freshly-cut Douglas fir (Pseudotsuga menziesii) logs. To evaluate the effects of physical penetration of bark and wood and transmission of basidiomycete compared with ascomycete fungi by insects, 360 experimental logs were assigned to five replicate sites, each with 12 heterotroph×moisture treatment combinations in 1995. Half of the logs in each heterotroph treatment received normal rainfall and half were placed individually under elevated clear plastic tents to reduce water inputs. Respiration was measured every 1-3 months. In 1996 and 1997 a different log representing each treatment combination was harvested from each replicate and analyzed for the presence of inoculated and colonizing fungi. Logs inoculated with decay fungi had higher respiration than uninoculated logs but this effect only approached significance (P=0.08) during the first season. Respiration was significantly higher in sheltered than in exposed logs. Our results indicate that respiration and wood decomposition rates may be depressed by high moisture content in the wet forests of the coastal Pacific Northwest.

Influence of Experimental Flooding on Litter Dynamics in a Rio Grande Riparian Forest, New Mexico

AbstractFlow regulation, which has largely eliminated flooding along the Rio Grande in central New Mexico, has substantially changed the riparian ecosystem. We investigated managed flooding as a means of restoring ecosystem function. After collecting baseline data during 1991 and 1992 in two riparian forest sites that had not flooded for about 50 years, we flooded an experimental site for 27–32 days during late spring of 1993, 1994, and 1995, leaving the reference site unflooded. During the final year of the study we compared these sites to two additional sites located within the riverside levee, one of which has been flooding naturally while the second remained largely unflooded. Three years of experimental flooding did not change the total biomass of either woody debris or forest‐floor litter at the experimental flood site. Both woody debris and forest‐floor litter, however, were significantly lower at the natural flood site than at the experimental flood site and two unflooded sites. Leaf and wood decomposition rates increased with flooding. The decay rate for cottonwood logs at the unflooded site (0.010 per year) predicted a half‐life of 69.3 years, while the decay rate of 0.065 per year after 3 years of experimental flooding predicted a half‐life of 10.6 years. This suggests that a decade of annual flooding may be used to restore the organic debris to pre‐regulation levels. Flooding may also have caused an increase in litter production. These results suggest that experimental flooding has initiated a process of restoring ecosystem function within the riparian forest.

Fallen wood decomposition ofPinus koraiensis andTilia amurensis

Fallen wood decomposition rate ofPinus koraiensis andTilia amurensis in broadleaved Korean pine forest was studied in this paper. The result showed that decomposition rate of fallen wood was different from that of little diameter wood and coarse woody debris for the same tree species. Fallen wood decomposition was generally rotten from outside to inside. And decomposition speed of fallen woods was different according to tree species and site, and it was also related to diameter of fallen woods. Decomposition depth ofTilia amurensis fallen wood for 17 years was 14 cm, but that ofPinus koraiensis in the same condition was less than 7 cm.Tilia amurensis was decomposed faster thanPinus koraiensis. For same tree species, if the diameter was small, the decomposition speed was quick.

Microbial Biomass and Activity in a Subarctic Soil Ten Years After Crude Oil Spills

AbstractThis study documents the residual effects of summer and winter experimental oil spills on soil 10 yr after application. Measurements included adenosine triphosphate (ATP) levels, in vitro carbon dioxide evolution, cellulose and wood decomposition, soil N, and total and non‐oil C. About 18 and 14 kg petroleum residues per m2 remained in the soil in the winter and summer spills, respectively, and no reinvasion of plants had occurred in areas heavily impacted by the spills. Soil ATP levels averaged about 100 mg m−2 in the control soils and were about threefold higher than in the oiled soils, indicating reduced microbial biomass in the oily soils. There were no differences in in vitro CO2‐C evolution rates in the three soils, suggesting that there were similar levels of available substrate in both oiled and control soils. Cellulose and wood decomposition rates in the field were much lower in the oiled plots than in the unoiled soil. Nonpetroleum organic C levels averaged about 12 kg m−2 and were not significantly different between control and oiled soils, indicating that in the field little decomposition of organic matter had occurred in the oiled plots. Total N levels averaged about 5.5 kg m−2 in the oiled plots, which was significantly higher than the 4 kg N m−2 in the control plots. This was possibly due to N deposition of parts of plants killed by oil and to N2 fixation coupled with reduced N losses from the oiled soils. Ammonium‐N accumulated in the oiled soils at much higher levels than in the control soil. Results of this study showed that crude oil spills in subarctic forests can have long‐lasting effects on soil biological properties.

Decomposition of Douglas-fir and red alder wood in clear-cuttings

Decomposition rates of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and red alder (Alnusrubra Bong.) wood (simulating logging residues) were determined in clear-cuttings at the Charles Lathrop Pack Experimental Forest of the University of Washington, which is located approximately 120 km south of Seattle, WA. The influence of diameter (1–2, 4–6, and 8–12 cm), vertical location (buried, on the soil surface, and elevated), season of logging (summer and winter), aspect (north and south), and wood temperature, moisture, and chemistry on wood decomposition rates were determined. Red alder wood decomposed faster (k = 0.035–0.517 year−1) than Douglas-fir wood (k = 0.006–0.205 year−1). In general, buried wood decomposed faster than surface wood, which decomposed faster than elevated wood. Small diameter wood generally decomposed faster than larger diameter wood. Aspect and season of logging had little influence on decomposition rates. Moisture and temperature were the dominant factors related to Douglas-fir wood decomposition, with initial chemistry playing a minor role. Initial wood chemistry, particularly soda solubility, was the dominant factor related to red alder wood decomposition.

Carbon dioxide release from decomposing wood: Effect of water content and temperature

The use of gas chromatography to measure carbon dioxide evolution from decomposing wood was evaluated and found useful to assess the rate of wood decomposition. An increase in temperature from 5–25°C was accompanied by an increase in CO 2 evolution. Increase in water content was accompanied by an increase in CO 2 evolution. When higher temperatures accompanied high moisture contents CO 2 evolution often levelled off or decreased. This was attributed to a decline in the rate of O 2 diffusion to concentrations insufficient to meet the demand. Increase in branch length showed a similar effect.