Biology Reference
In-Depth Information
“not cultivated.” The second dimension,
nature conservation focus
, distinguishes
between core nature conservation area (reference habitat, designed habitat) and
matrix areas (anthropogenic habitat, abandoned habitat) that surround the core
areas. In core conservation areas, the availability of nature conservation resources
and management capacity tend to be higher, and conflicts with alternative manage-
ment objectives, such as production, tend to be lower than in matrix habitat. The
prototypical nature of the four habitat types may be an indication that they are a
solid basis for theoretical thinking about biotic invasions from a habitat modifica-
tion perspective.
5.3 Anthropogenic Habitat
5.3.1 Habitat Characteristics
Anthropogenic habitats include agricultural and urban land, plantation forestry, ruderal
and waste sites, or roadsides. These sites are characterized by high levels of unused
resources (especially light and nutrients), frequent or large disturbances, and high inputs
of alien species propagules (Fig. 5.2). Species diversity is often low, and empty niche
opportunities for invasive species are common (cf. Dietz and Edwards 2006). Dietz and
Edwards (2006) suggest the term
primary invasions
to characterize invasions in anthro-
pogenic habitat in contrast to
secondary invasions
of less disturbed habitat.
Fig. 5.2
Invasions in anthropogenic habitat. Weedy alien species typically invade persistently
disturbed, anthropogenic habitats. In Hawaii, weed communities along roadsides at high eleva-
tions above c. 1,500 m asl. are dominated by European weeds that were historically introduced
through agriculture (e.g.
Anthoxanthum odoratum, Holcus lanatus,
or
Verbascum thapsus
).
Lowland and high elevation individuals of these species apparently differ ecologically (Gabi
Jakobs, unpublished data), and it may be that they have adapted to local conditions in roadside
vegetation (Photo Eva Schumacher)
