The myth of plant species saturation

Ecology Letters
By: , and 



Plant species assemblages, communities or regional floras might be termed ‘saturated’ when additional immigrant species are unsuccessful at establishing due to competitive exclusion or other inter-specific interactions, or when the immigration of species is off-set by extirpation of species. This is clearly not the case for state, regional or national floras in the USA where colonization (i.e. invasion by exotic species) exceeds extirpation by roughly a 24 to 1 margin. We report an alarming temporal trend in plant invasions in the Pacific Northwest over the past 100 years whereby counties highest in native species richness appear increasingly invaded over time. Despite the possibility of some increased awareness and reporting of native and exotic plant species in recent decades, historical records show a significant, consistent long-term increase in exotic species (number and frequency) at county, state and regional scales in the Pacific Northwest. Here, as in other regions of the country, colonization rates by exotic species are high and extirpation rates are negligible. The rates of species accumulation in space in multi-scale vegetation plots may provide some clues to the mechanisms of the invasion process from local to national scales.

Publication type Article
Publication Subtype Journal Article
Title The myth of plant species saturation
Series title Ecology Letters
DOI 10.1111/j.1461-0248.2008.01153.x
Volume 11
Issue 4
Year Published 2008
Language English
Publisher Wiley
Contributing office(s) Fort Collins Science Center
Description 10 p.
First page 313
Last page 322
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