240 Basic principles for molding land mosaics
(D) Grain size of the mosaic.Acoarse-grained landscape (mainly composed of
large patches) that contains fine-grained areas (mainly small patches) is
better than either type alone, because it effectively provides for many
large-patch benefits, multi-habitat species including humans, and a wide
range of habitats and natural resources (Figure9.2).
(E) Mosaic pattern and multi-habitat species. Species (and people) that regularly
use different habitats or land uses are favored by convergency points
(junctions where three or more habitats converge), adjacencies (differ-
ent combinations of adjoining habitat types), and habitat interspersion
(habitat types scattered rather than aggregated).
(F) Environmental gradients and patchiness.Environmental gradients with
gradual ecological change over space are sometimes evident, though
patchiness with distinct boundaries predominates on land, because of
patchy substrates and especially human activities that typically sharpen
boundaries.
(G) Nature andagrid.Aregular grid, such as of roads and strip development,
may be the ecologically worst way to distribute a small amount of built
area over a natural landscape, since the grid leaves only small natural
patches, truncates connectivity, and removes much of the irregularity
and heterogeneity characteristic of nature’s species-rich communities.
(H) Key variables of urban areas.Human population density and spatial prox-
imity are considered to be the two leading variables, with functional-
ity the third, providing understanding and predictive ability for mostGood, bad, and interesting patterns in urban regions
Landscape change
(A) Ecologically optimum change. The optimum way to change a large natural
landscape to a less ecologically suitable one is to progressively remove
vegetation in strips from two adjacent sides of the landscape, maintain
afewlarge green patches in the middle phase, and then sequentially
remove the patches.
(B) Specific changes within an optimum sequence.Determining an optimum spa-
tial sequence for a changing landscape permits one to pinpoint at any
stage the best and worst locations for a specific change, either deleteri-
ous or beneficial.
(C) Spatial processes.With the spread of human activities, natural areas may
be perforated, dissected, fragmented, shrunk, and/or eliminated with
quite different ecological consequences, even though habitat loss and
isolation normally increase with all of the processes.