Exotic plant invasions over 40 years of old field successions: community patterns and associations

Abstract

While exotic plant species often come to dominate disturbed communities, long‐term patterns of invasion are poorly known. Here we present data from 40 yr of continuous vegetation sampling, documenting the temporal distribution of exotic plant species in old field succession. The relative cover of exotic species decreased with time since abandonment, with significant declines occurring ≥20 yr post‐abandonment. The number of exotic species per plot also declined with time since abandonment while field‐scale richness of exotics did not change. This suggests displacement occurring at small spatial scales. Life history types changed from short‐lived herbaceous species to long‐lived woody species for both native and exotic plant species. However, shrubs and lianas dominated woody cover of exotic plants while trees dominated native woody cover. The species richness of exotic and native species was positively correlated at most times. In abandoned hay fields, however, the proportion of exotic plant cover per plot was inversely related to total species richness. This relationship suggests that it is not the presence, but the abundance of exotic species that may cause a reduction in community diversity. While the development of closed‐canopy forest appears to limit most introduced plant species, several shade‐adapted exotic species are increasing within the fields. These invasions may cause a reversal of the patterns seen in the first 40 yr of succession and may result in further impacts on community structure.

Aquatic pollution increases the relative success of invasive species

“…Given this predisposition of exotics to occupy bare space, however, the relative success of invaders may decrease with time. For example, significant declines in abundance and richness of exotic plants have been found over time in old fields (Meiners et al 2002). Although we predict that continued environmental degradation would promote exotics over longer time periods as well, additional studies would be necessary to confirm this.…”

The role of land-use history in major invasions by woody plant species in the northeastern North American landscape

“…Nonetheless, few studies have directly addressed the relationships between land-use history and exotic plant invasions. Those studies that have examined these relationships have tended to focus narrowly on specific habitat types-for example old fields, secondary tropical forests and temperate forests-without comparing multiple land-use patterns across heterogeneous landscapes (Bartuszevige et al 2006;Hobbs 2001;Kulmatiski et al 2006;Lundgren et al 2004;Meiners et al 2002;Pascarella et al 2000). In highly altered landscapes, land-use history is arguably the dominant factor in disturbance regimes (De Blois et al 2002;Foster et al 1998), so we might expect that different patterns of land-use change will create distinct ''windows of opportunity'' for invasion (Hobbs 2000;, which should affect distributions of invasive plants.…”

Relative allelopathic potential of invasive plant species in a young disturbed woodland1

“…The research area was composed of 10 agricultural fields that had been abandoned 43-51 years prior. Successional processes in these fields have been described in detail from a series of permanent plots-the Buell-Small Succession Study (Pickett 1982, Myster and Pickett 1990, Meiners et al 2002.…”