INTEGRATING MULTI-SOURCE DATA TO QUANTIFY CHANGES IN BIOMASS AND SOIL ORGANIC CARBON DUE TO LAND-USE CHANGE IN THE BOREAL PLAINS ECOZONE, CANADA
Ha, Thuan Van 1976-
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Land use and cover change (LUCCs) is the second largest source of global carbon emission and there has been a growing interest in LUCCs to mitigate climate change effects. Global land-use change associated with cropland expansion, which is a major carbon source, was dominant in the last century. Abandoned cropland typically is a carbon sink and was observed in many regions in the recent decades. However, there has been little research on carbon balance resulting from LUCCs in agricultural landscapes, especially under abandoned cropland in Canada. Information on carbon balance resulting from LUCCs is necessary for national greenhouse gas (GHG) inventories as well as emission mitigation options. The primary objective of the study is to quantify carbon stocks and dynamics as consequences of LUCCs in the Boreal Plains Ecozone, Canada. Field measurement on carbon stocks in abandoned cropland was assessed at field sites in Saskatchewan. Vegetation C ranged from 7.6 to 90.1 Mg C ha-1 and increased linearly with stand age. Ecosystem C increased from 74.2 to 137.6 Mg C ha-1 after 41 years of abandonment (or net C sink of 1.9 Mg C ha-1 yr-1). In the agriculture region of the Boreal Plains Ecozone, land-use change accounted for 6.5% of the total area during the 1990-2000 period. Forest to cropland conversion was dominant on well-drained Chernozemic and Luvisolic soil orders. Abandoned cropland occurred mainly on poorly drained and acidic parent materials. LUCCs in agriculture region was estimated to be a net C sink of 0.76 ±0.3 Mg C ha-1 yr-1 during this period. In the agriculture-forest transition region of the Boreal Plains Ecozone, substantial land-use changes occurred in pasture (+76%) and summer fallow (-87.8%) over a 27-year period (1984 - 2011). The shrub and forest area was reduced -31.6% and -16.4%, respectively. Forest disturbances occurred mainly during 2005 – 2011. Substantial changes of summer fallow to annual cropland took place on the higher soil capability land and annual cropland to pasture conversion was more likely on lower capability soil classes. We estimated that LUCCs in the region was a net C source of approximately 552.7 Gg C across the research period or 0.07 Mg C ha-1 yr-1.
DegreeDoctor of Philosophy (Ph.D.)
SupervisorPennock, Dan; Bentham, Murray
CommitteeBedard-Haughn, Angela; Guo , Xulin; Huffman, Ted; Johnston, Mark; McConkey, Brian
Copyright DateOctober 2017
Soil carbon stock
Land use and cover change
Boreal plain ecozone.