Exam 3 Flashcards
Non-native organism that is introduced into an
ecosystem out of it’s native range and
establishes as part of the community and
competes for a particular niche
exotic species
A species becomes invasive when
they cause
ecological, environmental, or economic harm or when a
species is harmful to human health
Not all exotic species are
invasive - they must cause harm or significantly affect the native system to be considered invasive
Not all invasive species are
exotic, some native species can become invasive and cause harm to the ecosystem
through over population.
Problems Caused by Exotic Species
Take advantage of exploiting resources relative
to minimal constraints from limiting factors or
Outcompete native species for resources
Prevent access to resources for some species
Take advantage of lack of predators, natural
diseases/parasites that would otherwise control
their populations
Introduction of diseases and pests
purposefully brought into non-native
range
intentional introduction
non-intentional introductions
accidental introduction
examples of intentional introduction
Agriculture, live stock forage, horticultural ornamentals, biocontrol,
recreation, aesthetics
Deliberate attempt to surround a new area with familiar flora
and fauna
98% of the US crops and livestock are non-native and some
have become invasive
examples of accidental introduction
Jump dispersal via cargo transport, ballast water in ships,
accidental “hitch-hikers” with any sort of travel to non-native
ranges
Escape from transport or captivity, pets escaping into the wild
Numbers of non
natives birds
highest on
island nations:
New Zealand
and Puerto Rico
Accidental import of pathogenic fungus on ornamental
nursery cargo from Japan in early 1900’s
Wind dispersed, kills trees from the bark and cambium
chestnut blight
damages American elm
populations, vector and fungus are exotic
Introduced from Asia to Netherlands and then eventually
to US and dispersed by exotic elm bark beetle
Dutch Elm Disease
Japan, 1876 Erosion control, livestock feed Possible Biofuel ???
Kudzu
Introduced intentionally to prevent erosion along roadsides Crowds native aquatic and hydric species in wetlands Reduces water flow in wetlands and hydric environments Harms larval amphibians (mostly frogs) with plant tannins Managed with biocontrol – beetles (often exotic) released into it’s habitat and they eat the leaves of the plant eventually killing it
purple loosestrife
Native to southeast Asia Introduced as pets Hurricane disturbance and release/escape from breeding facilities in South Florida
burmese python
1890 introduced 48 birds from Shakespeare’s plays to Central Park, New York, nest thieves and impact on native breeding bird populations
starling
Introduced to Australia in 1930’s to control pests in the sugar industry Outcompetes native amphibians and devours native insects
cane toad
Humans as part of nature: the utilitarian view of wilderness
Pro: acknowledges the necessary human use of nature. Con: may result in the loss of the cultural, aesthetic, and functional roles wilderness plays.
Humans as separate from nature: the intrinsic view of wilderness
Pro: minimization of human impacts Con: limits the meaningful role humans may play in their
ecological surroundings. Con: led to the physical displacement of native peoples from
newly designated ‘nature’ reserves or to the erasure of their
historical influence on the landscape (green imperialism) Pro: the motivation for distinguishing humans from the rest
of nature also reflects the desire to determine what aspects
of the environment should be preserved in the face of
pervasive human impacts
resolving the tension, The acceptance of a paradox
humans are
separate from and part of nature
The tree in the garden argument:
A humanized wilderness does not have
the same connectedness of a “wild” and untouched wilderness
The pragmatic argument
The accelerating loss of species suggests we should discard our debates over the meaning of wilderness and instead focus on conservation and developing criteria to evaluate human impacts and prevent further degradation
The species-area argument:
Large, undeveloped, interconnected lands are essential for some species. Small developed tracts of land are unable to support the disturbance regimes, habitats, and resources for these species – thus we need large wilderness areas for protecting biodiversity.
The baseline argument:
Wild areas are models for ecological restoration and should be preserved in as rare a state as possible as reference conditions
