Effects of Land Use/Cover Change and Harvests on Forest Carbon Dynamics in Northern States of the United States from Remote Sensing and Inventory Data: 1992-2001

摘要

We examined spatial patterns of changes in forest area and nonsoil carbon (C) dynamics affected by land use/cover change (LUC) and harvests in 24 northern states of the United States using an integrated methodology combining remote sensing and ground inventory data between 1992 and 2001. We used the Retrofit Change Product from the Multi-Resolution Land Characteristics Consortium to quantify LUC. We then calculated C dynamics using C densities for major forest types based on US Forest Service Forest Inventory and Analysis data by forest, area for different statuses (i.e., afforestation, deforestation, and forest remaining forest) and incorporated county-level harvest data. Across the region, 16,740 km(2) of forestland changed to nonforest, whereas 9,120 km(2) of nonforest became forestland, a net loss of 7,620 km(2) of forestland during the period or 0.13%/year. The region as a whole functioned as a C sink of 627 Tg (1 teragram = 10(12) g) or 70 Tg of C/year. Regional C sequestration calculated using forest type identification at the state level was 5% higher than that from the county-level identification. Integrated annual effects of LUC and harvest on reducing C stocks at the state level varied substantially, ranging from 0.4% in North Dakota to 5.1% in Delaware with an average of 3.2% across the region (3.4% in the 13 northeastern states and 2.6% in the 11 northcentral states), compared with what it would be without these effects. We also found that within the region the annual LUC rate was significantly correlated with population density at the state level (P < 0.001). FOR. SCI. 57(6):525-534.