CELLULOSE DECOMPOSTION IN TROPICAL PEAT SWAMPS

Given that organic soil is a complex substrate and there are many environmental factors which directly or indirectly control its decomposition processes, the use of standard substrate simplify the system in that the effect of substrate quality could be eliminated and influence of certain environmental conditions such as edaphic factors, acidity and moisture could be focused on. In addition to the forest floor, decomposition potential down the peat profile can also be examined. Cotton strip assay was used to estimate decomposition potentials in tropical peat swamp occupied by different Shorea Albida peat swamp forest communities, The' Alan Batu' , the ' Alan Bunga' , the' Alan Padang' and the 'mixed Alan'forest communities. Greatest decay rates on the peat surface took place during the wet period. The moist condition of the wet months appeared to favour the growth and stimulate activities of decomposer population and soil invertebrates.Generally, 50% of cotton tensile loss is achieved after four weeks of exposure. The results suggest that cellulose decomposition is influenced by the environmental variables of hydrological regime, water-table fluctuation, aeration, moisture availability,waterlogging and the resultant anaerobiosis, peat depths, and micro-sites characteristics. Decomposition of cellulose is inhibited by waterlogging and the resultant anaerobiosis in thelower segment of the cotton strip during wet periods and under dry conditions in the surface segment of the cotton strip during periods of less rain.

Impaired cellulose decomposition in a headwater stream receiving subsurface agricultural drainage

Background:Agricultural development of former wetlands has resulted in many headwater streams being sourced by subsurface agricultural drainage systems.Subsurface drainage inputs can significantly influence stream environmental conditions,such as temperature,hydrology,and water chemistry,that drive ecological function.However,ecological assessments of subsurface drainage impacts are rare.We assessed the impact of an agricultural drainage system on cellulose decomposition and benthic respiration using a paired stream study in a headwater branch of Nissouri Creek,in Ontario,Canada.Adjacent first order segments sourced by a spring-fed marsh and a cropped field with subsurface drainage,as well as the adjoining trunk segment,were sampled over a year using the cotton strip assay to measure cellulose decomposition and benthic respiration.Results:Assessments of cellulose decomposition revealed a one-third reduction in the drainage-sourced segment compared to marsh-sourced segment.Between segment differences in cellulose decomposition were associated with reduced summer temperatures in the drainage-sourced segment.Impacts of stream cooling from the drainage-sourced segment were transmitted downstream as cellulose decomposition was slower than expected throughout the drainage-sourced segment and for several hundred meters down the adjoining trunk segment.Benthic respiration only differed between the drainage-and marsh-sourced segments in spring,when stream temperatures were similar.Conclusions:Our findings suggest there may be a widespread reduction in cellulose decomposition in streams across similar agricultural regions where subsurface drainage is prevalent.However,cooling of streams receiving significant amounts of water inputs from subsurface drainage systems may impart increased resiliency to future climate warming.