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Post-fire dynamics of the boreal forest floor: Measurement and modelling of long-term carbon accumulation in upland forests

Posted on:2003-10-24Degree:Ph.DType:Dissertation
University:University of Alberta (Canada)Candidate:Nalder, Ian AnthonyFull Text:PDF
GTID:1463390011481785Subject:Agriculture
Abstract/Summary:
Forest floor carbon (FFC) dynamics over the life of a stand, and the consequent climate change implications, are investigated through a literature review, field sampling of six chronosequences and computer simulation. The six chronosequences, encompassing 80 forest stands, were based on two tree species, Pinus banksiana and Populus tremuloides , in each of three climatic zones in the western Canadian continental boreal forest. To aid this study, a novel corer for efficient forest floor sampling was developed, as well as a new interpolation technique to estimate climatic variables for each of the 80 sampled stands. For the simulations, two existing patch models using different approaches were tested (FORSKA2V and BORFOR), but both gave poor results and had inherent flaws for this region. Instead, a carbon input-output model was developed based on the decay algorithms of CENTURY and litter inputs that were defined by regressions of tree, shrub and moss data from the chronosequences.; The forest floor was a major, labile store of organic carbon, as well as being an important control of nutrient cycling and soil thermal and moisture regimes. To examine FFC dynamics, it was hypothesized that FFC was related to stand age, species and climate. The field study found that there was a difference between species, and that stand age and climate affected P. tremuloides FFC but not that of P. banksiana. Because of these effects, FFC storage was expected to be sensitive to a changing climate due to direct climatic effects as well as altered disturbance intervals and changes in species distribution. The model supported the hypothesized age and species effects, but climatic effects were not evident. To resolve discrepancies between observed and simulated patterns, and to allow for model improvements, there is a need to understand controls on shrub and moss/lichen growth, to better quantify litter from logs and fine roots, and to confirm appropriate decay rates for forest floor materials. It is concluded that the forest floor is an important store of carbon that will be sensitive to a changing climate, although improved models will be required to quantify such changes.
Keywords/Search Tags:Forest floor, Carbon, FFC, Climate, Dynamics, Model
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