Scale and plant invasions: A theory of biotic acceptance.
Citation
Catherine S Jarnevich, Geneva W Chong, Thomas J Stohlgren, and Paul H Evangelista, Scale and plant invasions: A theory of biotic acceptance.: .
Summary
We examined the relationship between native and alien plant species richness, cover, and estimated biomass at multiple spatial scales. The large dataset included 7051 1-m2 subplots, 1443 10-m2 sub- plots, and 727 100-m2 subplots, nested in 727 1000-m2 plots in 37 natural vegetation types in seven states in the central United States. We found that native and alien species richness (averaged across the vegetation types) increased significantly with plot area. Furthermore, the relationship between native and alien species richness became increasingly positive and significant from the plant neigh- bourhood scale (1-m2) to the 10-m2, 100-m2, and the 1000-m2 scale where over 80% of the vegeta- tion types had positive slopes between native [...]
Summary
We examined the relationship between native and alien plant species richness, cover, and estimated biomass at multiple spatial scales. The large dataset included 7051 1-m2 subplots, 1443 10-m2 sub- plots, and 727 100-m2 subplots, nested in 727 1000-m2 plots in 37 natural vegetation types in seven states in the central United States. We found that native and alien species richness (averaged across the vegetation types) increased significantly with plot area. Furthermore, the relationship between native and alien species richness became increasingly positive and significant from the plant neigh- bourhood scale (1-m2) to the 10-m2, 100-m2, and the 1000-m2 scale where over 80% of the vegeta- tion types had positive slopes between native and alien species richness. Both native and alien plant species may be responding to increased resource availability and/or habitat heterogeneity with in- creased area. We found significant positive relationships between the coefficient of variation of na- tive cover in 1-m2 subplots in a vegetation type (i.e. a measure of habitat heterogeneity), and both the relative cover and relative biomass of alien plant species. At the 1000-m2 scale, we did find weak negative relationships between native species richness and the cover, biomass, and relative cover of alien plant species. However, we found very strong positive relationships between alien species richness and the cover, relative cover, and relative biomass of alien species at regional scales. These results, along with many other field studies in natural ecosystems, show that the dominant general pattern in invasion ecology at multiple spatial scales is one of “biotic acceptance� where natural ecosystems tend to accommodate the establishment and coexistence of introduced species despite the presence and abundance of native species.
Published in Preslia, volume 78, issue 4, on pages 405 - 426, in 2006.
