MAPPING FOREST INVENTORY ATTRIBUTES ACROSS CONIFEROUS, DECIDUOUS AND MIXEDWOOD STAND TYPES IN THE NORTHWEST TERRITORIES FROM HIGH SPATIAL RESOLUTION QUICKBIRD SATELLITE IMAGERY

摘要

Conducting vegetation inventories that describe the state of forests in the Northwest Territories (NWT) is challenging due to the large geographic extent of forest resources that are not easily accessible. The federal (Natural Resources Canada, Canadian Space Agency) and territorial (Government of NWT) governments recently completed a satellite-based land cover map of the forested areas of the NWT in the Earth Observation for the Sustainable Development of Forests (EOSD) project with Landsat Thematic Mapper data. Within the framework of the EOSD land cover map, this project is modeling and mapping four forest inventory attributes (stand height, crown closure, stand volume and aboveground biomass) from panchromatic and multispectral Quickbird satellite imagery. The image derivatives from Quickbird used to derive inventory attributes depends on whether the stand types were predominately comprised of coniferous, deciduous or mixedwood species. For coniferous species, image tree shadows derived from the panchromatic Quickbird image were used to compute the shadow fraction, of which image estimates of the four inventory attributes were within 10 to 15 percent of independent field measurements. Due to differences in crown morphology between coniferous and deciduous stands, image shadow fraction was not a good predictor of the forest inventory attributes for deciduous and mixedwood species. A first-order texture measure based on variance from the panchromatic image resulted in image models for deciduous species with adjusted R{sup}2 values that ranged from 0.50 to 0.62. Estimating forest structure from mixedwood stands were more difficult, and required a combination of both panchromatic and multispectral image bands as estimators of the forest inventory variables.