Data bases used in studies of different types of land base changes.

Five categories of significant changes affecting forest area are: 1) afforestation; 2) deforestation; 3) forest fragmentation; 4) forest parcelization; and 5) increased numbers of structures, such as houses, on forest land.

Land Base Change	Coverage	Data Bases
Deforestation	48 contiguous States; 1982 -1997, with national updates for 2001 and 2003	USDA NRCS 2001
Afforestation	Annual tree planting by State, 1980 to 1998; periodic estimates of reversions to forests	USDA Forest Service Tree planting reports; periodic and annual FIA surveys
Forest fragmentation	1992, with another in progress	National land cover data base
Forest parcelization	Periodic owner surveys	National forest landowner survey
Structure additions to forests	Decadal national census; special studies	USDC Census Bureau; Oregon structure counts (contact: Dept of Forestry)
Urban forest changes	National	USDC Census Bureau

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