Agriculture Reference
In-Depth Information
species to the anthropogenic-based short fire return intervals, whereas most alien
herbs are favored by this fire regime. Similar changes likely occurred in Chile but
due to European colonization hundreds of years earlier than in California, we
have little documented evidence of type conversion. The extent of impacts from
invasive herbaceous species is far less widespread in the Cape region and south-
western Australia where oligotrophic soil conditions restrict the establishment of
invasive annual grasses and forbs from the Mediterranean Basin. Invasion and
establishment of woody acacia and pines in the Cape region have impacted fire
dynamics by increasing fire intensities.
Although shrubland and woodland landscapes in the Mediterranean Basin have
been greatly impacted by humans, both resprouting and obligate reseeding woody
species in the region appear to exhibit higher levels of resilience to disturbance,
including short fire return intervals, than those generally exhibited by woody
species in the other four MTC regions. Nevertheless, an inherent resistance to
alien species establishment in this region is threatened by changes in land use and
global climate change.
All five MTC regions face expected increases in fire frequency under climate
change scenarios. Invasive species represent threats not only through their direct
impacts on community structure and composition, but also by promoting flam-
mable herbaceous invaders that have the potential to induce powerful feedforward
processes and thereby fundamental changes to ecosystem function.
