Diversity–invasibility relationships across multiple scales in disturbed forest understoreys

Abstract

Non-native plant species richness may be either negatively or positively correlated with native species due to differences in resource availability, propagule pressure or the scale of vegetation sampling. We investigated the relationships between these factors and both native and non-native plant species at 12 mainland and island forested sites in southeastern Ontario, Canada. In general, the presence of non-native species was limited: \20% of all species at a site were non-native and non-native species cover was \4% m -2 at 11 of the 12 sites. Non-native species were always positively correlated with native species, regardless of spatial scale and whether islands were sampled. Additionally, islands had a greater abundance of non-native species. Nonnative species richness across mainland sites was significantly negatively correlated with mean shape index, a measure of the ratio of forest edge to area, and positively correlated with the mean distance to the nearest forest patch. Other factors associated with disturbance and propagule pressure in northeastern North America forests, including human land use, white-tailed deer populations, understorey light, and soil nitrogen, did not explain non-native richness nor cover better than the null models. Our results suggest that management strategies for controlling non-native plant invasions should aim to reduce the propagule pressure associated with human activities, and maximize the connectivity of forest habitats to benefit more poorly dispersed native species.

Factors associated with alien plant richness, cover and composition differ in tropical island forests

“…Ohlemüller et al () found that forest structure had only small effects on alien species richness in forests of the South Island of New Zealand while basal area had a consistent negative effect on alien species richness. Ohlemüller et al () as well as others (e.g., Tanentzap, Bazely, & Lafortezza, ) found strong effects of forest fragmentation metrics on alien species richness. These effects may partly include the effect of fragmentation on forest structure as, for instance, fragmentation creates new edges that affect large trees (e.g., Laurance, Delamonica, Laurance, Vasconcelos, & Lovejoy, ).…”

The spatial and temporal effects of fire on insect abundance in Mediterranean forest ecosystems

“…In this study, the number of Coleoptera increased significantly Table 2 Analysis of variance (ANOVA) assessing the spatial and temporal variation of insect abundance in response to fire distance. Sampled data were grouped considering distance classes (0-300 m and 300-600 m) and survey years (2009 and 2010 during the survey period due to the changes in ecosystem structure and plant species turnover (Ewers et al, 2009;Lafortezza et al, 2010;Tanentzap et al, 2010). Gandhi et al (2001) suggest that fire residual patches provide important habitats for a number of terrestrial Coleoptera.…”

Influence of forest fires on insect diversity: a case study in Apulia

“…La biodiversità è un tema centrale in ecologia fore stale, specie se considerata in termini di influenza sulla stabilità delle popolazioni in risposta ad eventi perturbativi interni e/o esterni al sistema (Ewers et al 2009, Tanentzap et al 2010.…”