Geography 3412 Conservation Practice: Ecosystems Management
Class Notes
Chap 9: Managing Biodiversity Across Landscapes
This chapter takes up the challenge of conservation across varied landscapes, especially those with different levels of preservation.
Preserved areas, natural areas, reserves, etc.—all terms for areas set aside for the preservation of nature. The most well-known of these in the US are "national parks" and "wilderness areas"---(a brief review of NPS and Wilderness System).
But many of these "nature preserves" were not designed well for the conservation of biodiversity: they preserve rugged, high alpine terrain, or particular landmarks, like the geysers in Yellowstone or the very large canyon of the Colorado River. Many were created from land that was less suited for development, and maybe less naturally-productive.
Reserve design has emerged as an element of ecosystems management, with new thinking: add core preserves to better represent the array of biodiversity across the landscape (coarse filter), and integrate cores with buffers and surrounding landscapes, re-open migration corridors among preserves, and modify some uses of developed land to better accommodate species (e.., make roads and subdivisions less a sink for bears—fine filter).
Ecosystems or Species?
Protect species, one by one or by community------vs. protest ecosystems?
We’ve asked this question in different ways during this semester—here it is again in terms of landscape approaches.
The "coarse filter" approach: protect ecosystems at a broad scale, and you will protect the species in those ecosystems. You need to preserve them in some distribution that mimics their natural distribution, size, shape and connectivity across the landscape----BUT, you must live with the simple fact that you are operating within landscape mosaics that have been altered by hum an land uses (e.g., you may be trying to preserve not the original distribution, but some fraction f that distribution, and you may try to maintain that fraction or ratio among the ecosystems or habitat patches.
The "fine filter" approach: preserve the specific habitats needed by individual species, guilds, etc.---e.g., enough habitat for grizzly bears. This is the more traditional approach.
In practice a blending if the two approaches is used.
Landscape-Level Considerations
The Protected Area: the design and improvement of protected areas is key to conserving biodiversity, but it must recognize that protected areas lie in a matrix of less-protected and developed areas.
Area, shape and isolation of protected areas are key characteristics that affect their ability to play a role on large-scale conservation.
Area: relates to area-sensitive species and other factors of ecosystem function, especially stochastic factors like catastrophe and variability.
Shape affects effective area via the edge effect (case is Flat Tops Wilderness in Colo.).
Isolation: recognize that most species in human-dominated landscapes are in meta-populations, so dispersal is key to their preservation.
Movement corridors
Why species move:
Types of movement corridors
Developing Movement Corridors
Select species of concern or umbrella species. Evaluate movement needs.
Identify patches/landscapes/sites to be connected
Map corridor and assess its landscape (human and natural) features
Design and implement---MONITOR!
Corridor Features:
Gaps: size of gap and permeability must be scaled to species behavior.
Width: less if similar to matrix; wider if dissimilar; wider if species is intolerant of human contact. Wider if longer.
Length: as short as possible, but commensurate with movement behavior.
Conserving Across Administrative Boundaries
This is the inevitable challenge of any landscape-scale conservation:
Boundary Qualities