Urban Regions : Ecology and Planning Beyond the City

38 Planning land

1

A few large

natural-vegetation

patches

2

Vegetation

along

major

streams

3

Connectivity

between

large patches

4

Small patches/corridors

scattered across

less-suitable matrix

5

Small patches/corridors

clustered around

large patches

Figure 2.2Fivepriorities for nature conservation illustrated with the

patch--corridor--matrix model. Patches and corridors are natural or semi-natural

vegetation and the background matrix is less-suitable land use. Numbered in the

typical order of conservation priority. Adapted from Forman (1995).

lands. Migratory birds depend on and move across many ecoregions. The TNC

approach is unique and focused on regions. In contrast, each government

agency and NGO and local organization has its own approach to conservation

planning.

Large green patches and corridors(emerald network)

For yearsItookphotographs out of airplane windows around the world.

Perhaps the most striking and ubiquitous pattern evident is the fragmentation of

nature into little parcels. While habitat loss is overwhelmingly the giant cause

of nature’s problems (Wilson 1992, Forman 1995, Wilcoveet al.1998), habitat

degradation and habitat fragmentation are the two giants following in the scene.

Most of the principles used by The Nature Conservancy for ecoregions could

be used by planners and policymakers for familiar political/administrative units,

such as nations, states/provinces, and counties/towns. Thus using the patch--

corridor--matrix model (Chapter1;Forman 1979b,1995), the largest extensive

natural patches can protect an aquifer, connected stream headwaters, large-

home-range species (e.g., tigers and wolves), viable populations of interior species,

and natural disturbance regimes (Figure2.2). Analogously, large patches at a

town scale can protect some of these resources, and small patches provide gen-

erally small, but different benefits.