U.S. lumber production peaked at 40.5 billion board feet in 2005 and plunged to 23.4 billion in 2009, according to Western Wood Products Association and Southern Forest Products Association estimates.
Additionally, spatial association index was computed to characterize the spatial interactions between forest class and other target land use types of interest.
另外，计算景观类型间的空间关联指数，以刻画森林与其他土地利用类型的空间交互效应。
3
Forest vegetation was classified into 3 vegetation type groups, 9 vegetation types, 41 association.