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En
vir
onment
Part Three: indicators
lEvEl Of MEAsurEMEnT: Outcome.
dEfiniTiOn: Species abundance is a reflection of the total number of an individual species in a defined
geographic area. Species abundance is the average number of a specific species found in a given area
(e.g., per hectare, square kilometer, square mile, etc..); this is an indication of how common a given
species is. The distribution of an individual species is defined as the geographic or spatial area within
which that species can be found. Within any area, the spatial distribution of a particular species may be
clustered in one location or may be more evenly distributed throughout the area.
Species' abundance and distribution are key components of species diversity. When the pattern of di-
versity in protected areas or target areas is described only by the total number of different species
(richness), the relative population size and geographic range can be missed (i.e., whether species are
relatively rare or common). Therefore, a more comprehensive species monitoring effort should include
data collection on the number of selected species in a defined target area as well as mapping of the
species' geographic distribution, taking into account temporal changes such as seasonal or breeding
patterns. Selection of the most appropriate species for monitoring abundance and distribution will vary
depending on the species populations and local threats.
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sPECiEs ABundAnCE And disTriBuTiOn
disAGGrEGATE: Type of species, type of targeted area.
PurPOsE: Preserving species diversity is critical to ecosystem health and function including energy fixa-
tion, chemical cycling, soil maintenance, ground water purification and access to clean drinking water,
protection against flooding, and maintenance of healthy populations of pollinators. Monitoring spe-
cies abundance and locations can provide early warning of changes in conditions that may negatively
impact biodiversity overall and may pinpoint critical areas and species to focus on.
Large wildlife species are often the most affected by human activities because they have large habitat
and nutritional requirements, are seldom found in high densities, and have relatively low reproductive
rates. The goal is to maintain or increase species abundance of prominent groups of species within natu-
ral variation. Collecting data on trends in abundance may help guide project management decisions.
dATA sOurCEs: Transect survey, mapping, secondary records (existing species data).
# of individuals of a specific species identified in a survey of the target area
total target area surveyed
Calculation
x 100