Factors explaining alien plant invasion success in a tropical ecosystem differ at each stage of invasion

• Published in: The Journal of ecology Vol. 97; no. 4; pp. 657 - 665
• Main Authors: Dawson, Wayne, Burslem, David F. R. P., Hulme, Philip E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.07.2009; Blackwell Publishing; Blackwell Publishing Ltd; Blackwell
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; animals; Biological and medical sciences; biological invasions; Biological taxonomies; Biological variation; Botanical gardens; Canopies; climate matching; colonizing ability; East Africa; Ecological invasion; ecosystems; Flowers & plants; Forest ecology; Forest regeneration; Fruits; Fundamental and applied biological sciences. Psychology; General aspects; Growth rate; Human ecology; Indigenous species; introduced plants; Introduced species; introduction history; invasibility; Invasion Ecology; Invasive plants; Invasive species; life history; Nonnative species; Phylogenetics; Phylogeny; Plant ecology; Plant species introduction; planting; Plants; rain forests; rainforest; Rainforests; Seeds; shade tolerance; Statistical models; surveys; Synecology; Tanzania; taxonomy; Tropical environments; Tropical forests; tropics; Eastern Africa; East Africa; Africa; Tanzania; Climate; Life history; Introduced species; Biological invasion; Taxonomy; Rain forest; Tropical zone; introduction history; biological invasions; Ecosystem; rainforest; invasibility; climate matching; Plant introduction; East Africa
• DOI: 10.1111/j.1365-2745.2009.01519.x
• ISSN: 0022-0477

1. Understanding why some alien plant species become invasive when others fail is a fundamental goal in invasion ecology. We used detailed historical planting records of alien plant species introduced to Amani Botanical Garden, Tanzania and contemporary surveys of their invasion status to assess the relative ability of phylogeny, propagule pressure, residence time, plant traits and other factors to explain the success of alien plant species at different stages of the invasion process. 2. Species with native ranges centred in the tropics and with larger seeds were more likely to regenerate, whereas naturalization success was explained by longer residence time, faster growth rate, fewer seeds per fruit, smaller seed mass and shade tolerance. 3. Naturalized species spreading greater distances from original plantings tended to have more seeds per fruit, whereas species dispersed by canopy-feeding animals and with native ranges centred on the tropics tended to have spread more widely in the botanical garden. Species dispersed by canopy-feeding animals and with greater seed mass were more likely to be established in closed forest. 4. Phylogeny alone made a relatively minor contribution to the explanatory power of statistical models, but a greater proportion of variation in spread within the botanical garden and in forest establishment was explained by phylogeny alone than for other models. Phylogeny jointly with variables also explained a greater proportion of variation in forest establishment than in other models. Phylogenetic correction weakened the importance of dispersal syndrome in explaining compartmental spread, seed mass in the forest establishment model, and all factors except for growth rate and residence time in the naturalization model. 5. Synthesis. This study demonstrates that it matters considerably how invasive species are defined when trying to understand the relative ability of multiple variables to explain invasion success. By disentangling different invasion stages and using relatively objective criteria to assess species status, this study highlights that relatively simple models can help to explain why some alien plants are able to naturalize, spread and even establish in closed tropical forests.