SFF's approach to ecosystem-based planning is applicable at a full range of spatial scales from large sub-continental and regional landscapes to small watersheds and individual patches or ecosystem types. In order to protect ecosystem health and biodiversity at all scales through time, ecosystem-based planning needs to begin with as large a landscape as possible to ensure that ecological processes are maintained throughout the region as planning proceeds to landscapes of multiple watersheds, to individual watersheds, and eventually to patches or individual ecosystem types.

Silva develops ecosystem-based plans so that the protected networks of ecosystems designed at each scale nest within those designed for larger areas. This approach not only provides for the most effective way to protect ecosystem health and biodiversity, but also results in an efficient planning system in terms of data interpretations, field assessments, map design, and structuring planning tools like geographic information systems (GIS) and aerial photo interpretation.

The design of protected networks of ecosystems employ the same set of five primary variables at each spatial scale:

1. Ecological sensitivity
2. Unique or special features
3. Representative features
4. Focal species
5. Connectivity

The expression of each of these five primary variables varies, depending upon the scale of planning. For example, at the large landscape level, an entire watershed may be a unique feature, because it is the last unmodified area with the full range of grizzly bear habitat. At the patch level, large snags and fallen trees of a particular species may be unique features. Along with the five primary variables listed above, each ecosystem-based plan utilizes specific variables that reflect the characteristics of the planning area and the overall objectives of the plan.

Designs for protected networks of ecosystems at each scale are developed from a combination of interpretation of various data bases, field assessments, and expert opinion. Each design is subject to modification based upon a field assessment and peer review of the design.

The three primary scales that we employ are described below. However, there are often intermediate scales, where plans are produced that fall between these primary scales. The precise structure of a multiple spatial scale ecosystem-based plan depends upon the ecological characteristics of the area being planned and the objectives for the plan.

Sub-Continental & Regional/Large Landscapes: PROTECTED AREAS NETWORK

A Protected Areas Network (PAN) consists of core reserves and linkages that provide for connectivity between core reserves, and throughout the landscape being planned. Core reserves and linkages need to be spatially well distributed across the planning area, and be inclusive of the five primary variables listed above. If the planning area is large, consisting of multiple landscapes, a PAN may be developed for the entire area, with finer scale PANs developed for landscapes within the large planning area. The common scales for analysis and map production of PANs range from 1:500,000 to 1:200,000

Landscapes and Multiple Watersheds: PROTECTED LANDSCAPE NETWORK

A Protected Landscape Network (PLN) is designed for a medium-size landscape that will be modified by human activities. The design of a PLN is followed by development of human use zones for the landscape and design of an economy for the planning area.

Considering the five primary variables described above, specific components of a PLN include:

· old growth or late successional forests; · riparian ecosystems, from large to ephemeral features; · wetlands and wetland complexes; · ecologically sensitive areas; · naturally rare ecosystem types; · linkages or corridors that provide connectivity between and within ecosystems, groups of ecosystems, and ecological communities; · ecosystems that provide habitat for rare, threatened, endangered genetic strains, species, and ecosystem types; and · ecological communities that are representative of the landscape.

The common scales for analysis and map production of PLNs range from 1:200,000 to 1:20,000.

Ecological Communities and Patches: PROTECTED ECOSYSTEM NETWORK

A Protected Ecosystem Network (PEN) is designed at the community or patch level to maintain ecosystem composition, structures, and functioning in areas modified by human resource extraction and/or other forms of human development. The design of a PEN is part of the development of a prescription for human use in a particular ecological community or patch. Considering the five primary variables described above, specific components of a PEN include: · large living and dead tree structures · small ecologically sensitive areas · ephemeral streams and wetlands · linkages between structures The common scales for analysis and map production for PENs range from 1:20,000 to 1:500.