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" Organic matter dynamics of coastal peat deposits in Sumatra, Indonesia "
M. A. Brady
J. P. Kimmins
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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1112947
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| Doc. No
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TLpq304406542
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| Main Entry
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J. P. Kimmins
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M. A. Brady
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| Title & Author
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Organic matter dynamics of coastal peat deposits in Sumatra, Indonesia\ M. A. BradyJ. P. Kimmins
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| College
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The University of British Columbia (Canada)
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| Date
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1997
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| student score
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1997
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| Degree
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Ph.D.
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| Page No
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258
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| Abstract
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Organic matter dynamics were investigated in the surface peat layer (acrotelm) in study sites traversing three raised ombrotrophic peat deposits, containing up to 3, 6 and 12m, respectively, of peat located on the east coast of Sumatra, Indonesia. The three deposits were uniform in climate, topography, surficial geology and were under continuous forest cover. Increased peat depth and distance from the edge of the deposit was associated with important changes in species composition, structure and morphology. To account for the differences in peat depth, I hypothesized that the relative importance of: (1) peat age, (2) organic matter decomposition and (3) litter additions, in controlling peat accumulation varies among the three deposits. Age differences, using C dating, did not account for variable peat accumulation. Peat at the clay-peat interface was approximately 4000 to 4500 years old in each study site, while acrotelm peat ranged from 45 to 660 years old. The relatively recent age of the acrotelm layer suggested that peat accumulation in the study sites was either at steady state or expanding. There were no significant differences in peat respiration rates between samples at different moisture levels. Significantly higher respiration rates, however, were measured in acrotelm peat from the 12m deposit compared with the same layer in the 9 and 6m sites in the same deposit and in the sites on the 3 and 6m deposits. Buried cotton strips disappeared at the same rate at all study sites. However, the disappearance of leaf litter from mesh bags was most rapid in the 3m site and slowest in the 12m site. Decay rates were mainly controlled by varying organic matter quality due to species composition differences across the gradient of increasing peat depth. Several chemical parameters were significantly correlated with indices of litter and peat decay in the following order of importance: soluble C fraction > lignin:N > C:N > P. Litter quality in the study sites was generally low compared to other tropical forests on nutrient poor soils. Organic matter additions varied between the three peat deposits. Rates of small and fine litterfall declined significantly while small and fine root mass was increased across the gradient of increasing peat depth. Preliminary measurements of root growth into mesh bags of root-free peat indicated higher production of small roots in the acrotelm of the 9 and 12m peat sites. A continuous 20-40 cm thick mat of fine and small roots present in the 12m site restricted aboveground litter fall from being preserved in the peat matrix below the root mat. High water table levels were important in controlling peat accumulation and decay in the 3 and 6m peat sites, while resource quality appeared more important in the 9 and 12m sites. (Abstract shortened by UMI.)
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| Subject
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Earth sciences
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Paleoecology
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