Natural Area Acquisition
Natural area acquisition will comprise 55% ($8.4 million) of Portland's local share spending. Acquisitions will be focused in Metro's regional target areas within the City of Portland (Columbia Slough, Forest Park connections, Johnson Creek, Tryon Creek, Fanno Creek, and Willamette Greenway) and in one local target area (Westside Wildlife Corridor). Acquisitions will be coordinated with Metro to supplement regional acquisitions within the city.
Acquisition of key natural areas implements the 2006 Natural Areas Acquisition Strategy, providing a connected system of wildlife habitat and connecting people with nature. Natural area acquisition also meets the goals of the 2005 Portland Watershed Management Plan: improving water quality, and restoring natural hydrology, physical habitat, and biological communities by protecting our green infrastructure.
General Acquisition Criteria
Four overall criteria for natural area acquisition were detailed:
- Protecting large, intact areas
Larger areas offer more protected interior habitat, shown to be required breeding and other life functions such as resting, foraging, hiding for many species. Portland metropolitan area studies have shown that habitat patches over 30 acres support breeding bird populations. Larger areas are also more efficient to manage and allow for more community access.
- Protecting sites with exceptional biodiversity values (habitats and species)
A site may demonstrate exceptional values based on its ability to support habitats and species identified as rare or under threat in Oregon or the metropolitan region, or because of its condition in providing highly functioning ecological habitat, with relatively few invasive species.
- Improving connectivity within a regional system of natural areas
Long-term sustainability of the natural area system depends on connectivity to larger protected areas outside of the city and between large protected natural area parks within the urban area. Connectivity is important for both aquatic and terrestrial ecosystems, allowing migration between large habitat areas.
- Buffering current natural areas
Common threats to urban natural areas include conflicting land uses and invasive species on their boundaries. Buffering currently protected areas can help reduce these threats, make management more efficient, and provide access to neighborhoods and a network of pedestrian and bicycle trails.