HR: 0800h
AN: B11D-0777    [Abstracts]
TI: Temporal Trends in Post-fire Regeneration Patterns of Boreal Forests Using 1 km AVHRR NDVI
AU: * Alcaraz, D
EM: da6f@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, 291 McCormick Rd., Charlottesville, VA 22903, United States
AU: Chuvieco, E
EM: emilio.chuvieco@uah.es
AF: Departamento de Geografia, Universidad de Alcala, Colegios 2, Alcala de Henares, Mad 28801, Spain
AU: Epstein, H
EM: hee2b@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, 291 McCormick Rd., Charlottesville, VA 22903, United States
AB: Forest fires are widely recognized as a major factor in global carbon budgets and are particularly important in boreal forests, where 37% of all carbon in the terrestrial biosphere is stored. Effects of climate change are evident in this region and will likely affect fire cycles, size, and severity. However, information is still relatively unavailable about the effects of burn characteristics on post-fire regeneration, and how burned areas differ from unburned areas in their responses to climate variation. Here, we analyzed the spatial variation of the NDVI temporal trends in post-fire regeneration as a result of burn severity, ecozone, land cover and latitude using a 1984-2006 1km AVHRR-NDVI time series for central Canada. The temporal trends were calculated using the seasonal Mann-Kendall trend test, a rank-based non-parametric test robust against seasonality, non-normality, missing values, and serial dependence. Burn severity was categorized in 4 groups from high to low: late-growing season fires (post July 20), early-season fires (pre July 20) in years of large fires, early-season fires in years of small fires and unburned areas. Negative temporal trends occurred in less than 4% of the sampled pixels. Increases of NDVI tended to be significantly lower at higher latitudes. Differences in NDVI were not significant across landcover types. Boreal Plains was the ecozone showing the highest positive trends in the NDVI; Boreal and Taiga Shields experienced moderate increases, while Taiga Plains showed minor increases. Our results show that the highest NDVI increases occurred in areas experiencing very severe fires during the late-growing season and in areas with non- severe, early-season fires. Unburned areas showed moderate NDVI increases.
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1630 Impacts of global change (1225)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1640 Remote sensing (1855)
DE: 3270 Time series analysis (1872, 4277, 4475)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting