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Endangered Species
Plants
are said to be endangered when the number of individuals is so
small that the species appears to be in danger of becoming extinct (globally
endangered), or when it is in danger of being extirpated within some defined
area, such as a state (state endangered). Species judged to be less immediately
in danger are said to be threatened. A third class of plants which
are rare and appear to be at risk of becoming threatened or endangered
are said to be of special concern. In Wisconsin there are currently
73 endangered, 65 threatened and 185 special concern species of vascular
plants. A list of
endangered, threatened and special concern species of vascular plants
for Wisconsin is available on the web.
Plant species become rare for several reasons. Some species may naturally be present at low numbers even if all conditions are favorable. It is also possible that a given species can become less common due to the constantly changing interplay between the physical features of the Earth and the other plants and animals. However, we are most concerned in those cases where the activities of people have exserted a strong negative effect on other species. In this regard, we have contributed to the rarity and possible extinction of individual species by our collective actions.
Common causes of rarity for plant species include conversion of their natural habitat into other, unsuitable habitats by agriculture, forestry, construction of home sites or roads, introduction of invasive exotic species of plants or animals, and intentional harvesting of plants. Loss of habitat seems to be the most important factor in many cases.
ROLE OF HERBARIA IN EFFORTS TO CONSERVE ENDANGERED SPECIES
Herbarium collections are an important part of the attempt to protect
endangered plants. Herbaria are the best source of information documenting
the presence of any species within an area. The plant vouchers stored
in herbaria have labels which describe where and when the plant was collected,
and (if the collector has done a good job) information on the type of
habitat, associated species and the size and health of the population
from which the voucher was taken. From this information, gathered from
all herbaria in the region, the researcher can get a good understanding
of how the species is distributed and how common it is. This label information
is also helpful in identifying what kind of habitat is necessary for the
species.
A herbarium is also an essential resource for the training of botanists who will study natural ecosystems and native plants, including endangered species. They are also often important sources of the published literature relevant to endangered species. When rare species are similar in appearance to other, more common species, the information necessary to distinguish them is usually gleaned from the information associated with the vouchers.
Biodiversity Topics: Introduction . Plants . Animals . Mammals . Birds . Reptiles & Amphibians . Arthropods . Spiders . Insects
© 2001-2004 The Cofrin Center
for Biodiversity and the University of Wisconsin Green Bay,
All Rights Reserved
Last
updated on
January 12, 2006