Land use history alters the relationship between native and exotic plants: the rich don’t always get richer

Abstract

Observational studies of diversity have consistently found positive correlations between native and exotic species, suggesting that the same environmental factors that drive native species richness also drive exotic species richness, i.e., ''the rich get richer''. We examined patterns of native and exotic plant species richness in temperate forests that have been undergoing reforestation since the turn of the twentieth century to test the influence of disturbance arising from land-use history on this relationship. Overall, we found no relationship between native and exotic plant species richness. Instead, we found a positive relationship between native and exotic richness in older but not younger-growth forests, suggesting that the same processes that drove exotic plant richness in older forests also facilitated native plants. In contrast, younger forests had similar numbers of native species relative to older forests, but 41% more exotic species and 24% more compacted soils. Moreover, exotic but not native species richness was positively correlated with increasing soil compaction across all sites. Overall, our results suggest that elevated exotic plant invasions in younger forests are a legacy of soil disturbance arising from agricultural practices at the turn of the century, and that native and exotic plants may respond differentially to disparate environmental drivers.

“The rich get richer” concept in riparian woody species – A case study of the Warta River Valley (Poznań, Poland)

“…On the other hand, in experimental plots and greenhouse studies, the success of invasive species is negatively correlated with species richness (Naeem et al, 2000;Kennedy et al, 2002). Parker et al (2009) found a positive correlation between native and exotic species richness only in some cases. However, there is a lack of case studies that apply this concept to explain the diversity of tree assemblages along rivers.…”

White-Tailed Deer Alter Specialist and Generalist Insect Herbivory Through Plant Traits

“…Research was conducted at the Smithsonian Environmental Research Center (SERC), a 2650-acre research preserve located on the western shore of the Chesapeake Bay (38.8860Њ N, Ϫ76.5500Њ W), MD. Forests are primarily secondary mesic forest growth 75Ð120 yr of age after agricultural abandonment (Parker et al 2010). The forest understory at SERC contains Ͼ200 native and non-native plant species, but spicebush (L. benzoin) is the most common understory shrub.…”

Novel Weapons Testing: Are Invasive Plants More Chemically Defended than Native Plants?

“…SERC and the surrounding areas are semi-rural and comprised of old fields, croplands, and forests. Nearly all forests are secondary, post-agricultural forests within which biological invasions are common [43], [50], [51]. We focused on 40 understory plant species that are abundant at SERC and in surrounding areas [43, Parker et al unpublished data], 21 species native to eastern Maryland and 19 introduced species, the majority of Eurasian origin (Figure 1, Table S1).…”