Landscape management - Ecological Applications: Toward a Sustainable World - page 299

number. These patterns provide clues for the design of nature reserves, in terms of
the importance of reserve size and connectivity among reserves in a network.
Species richness and biodiversity
Species richness is simply the total number of species present in a defi ned area.
Species richness is a key component of biodiversity , but the latter can also be viewed
at scales smaller (genetic diversity within species) and larger (the variety of ecosys-
tem types present) than the species. Some communities (e.g. tropical forests) contain
remarkably high species richness, refl ecting high productivity, a considerable range
of resources and a long evolutionary history producing saturated communities with
large numbers of specialists.
Landscape harvest management
Harvesting rarely takes place in a homogeneous landscape so an understanding of
landscape (or waterscape) structure and metapopulation dynamics is necessary
when devising management strategies. Marine protected areas may potentially
reduce the likelihood of overexploitation of a fi shery. Whether they do so depends,
among other things, on patterns of dispersal of larval stages away from protected
areas and towards fi shed zones. Harvest management in forests must also take
heterogeneity into account, depending on knowledge of the successional mosaic that
exists, and the contrasting harvest values (wood products, bushmeat, medicinal
plants) in different patches.
Pest control in the landscape
The effectiveness of pest control (whether in forestry, horticulture or pasture set-
tings) can be affected by the nature of the landscape in which it is carried out. A
greater variety of tree species or land uses in a production landscape may provide
refuges for natural enemies of forest or crop pests. Thus, the details of landscape
confi guration can infl uence the probability that predators and parasitoids will co-
occur with target pests in a metacommunity. From one perspective crop weeds are
undesirable but, in terms of biodiversity, farming practices that enhance the rich-
ness of noncrop plants have much to offer. It turns out that heterogeneity of land
use around arable fi elds can strongly infl uence the richness of weeds they contain.
Restoration landscapes
Many species use more than a single habitat, so reintroduction or protection of
threatened species requires knowledge of how they make use of the landscape at
large. When considering biodiversity in general, it is surprising how many species
occur even in modern cityscapes. However, some aspects of landscape heterogeneity
in cities are more crucial than others in determining species richness.
Designing reserve networks for biodiversity conservation or for multiple goals
Different parts of the globe vary dramatically in their species richness, and the
extent to which the biota is unique or endangered. At this global scale, the identifi -
cation of 'global hotspots' can guide international conservation efforts. At a national
or regional scale, the steps to designing a reserve network are to compile data on
biodiversity, identify conservation goals, select additional reserves to augment exist-
ing ones in a way that best achieves the conservation goals, implement conservation