Forest Plan Implementation
Procedures and Tools
Cumulative Effects
To analyze cumulative effects for projects on the Tongass it is necessary to consider the level of past and future development on adjacent non-National Forest System lands (non-NFS lands), in addition to that on NFS lands. The most prevalent forms of development in Southeast Alaska are timber harvest and road construction. Thus, it is important to estimate the past harvest and road development on both NFS and non-NFS lands, as well as future harvest and road construction on both land categories.
The Tongass geographic information system (GIS) library includes layers that describe existing vegetation, e.g., "size_density" (see the Size-Density Model), and roads ("infra_rds" for system roads and "all_rds" for unauthorized roads) on NFS lands. However, there are no library layers that adequately portray the vegetation and roads on all non-NFS lands in Southeast Alaska.
In order to quantitatively consider cumulative harvest and cumulative road development in the effects analyses for the 2008 Forest Plan Amendment Environmental Impact Statement, new GIS layers were developed for vegetation and roads on non-NFS lands. The development and use of these layers are discussed on the Web pages linked below.