Community Ecology

, Volume 12, Issue 2, pp 171–178 | Cite as

A meta-analysis of the ecological significance of density in tree invasions

  • C. E. L. DelmasEmail author
  • S. Delzon
  • C. J. Lortie


Species richness, resource availability, and disturbance are the primary factors considered in assessing the invasibility of plant communities. Nonetheless, the density of individuals in a community is a common and easy trait to measure. The ecological significance of the density of both native and invasive tree species was assessed using a systematic review and formal meta-analysis. The densities of recipient communities and invasive exotic tree species in novel ranges were identified in the published literature. In addition, we compared by means of a meta-analysis: (i) densities of invasive versus native species in invaded communities; (ii) densities of native species in invaded versus uninvaded communities; and (iii) densities of invasive species along distance gradients from initial locus of invasion. Invasive trees were found at higher densities than native species in recipient communities. Invasions by woody species were also recorded in communities with relatively low densities of natives suggesting that (i) low density forests may be more susceptible to invasion and/or (ii) density of the recipient community may be reduced during the invasion process. In addition, comparison of native species densities between invaded and uninvaded stands from the same community suggests that invasive trees negatively affect density of native trees once established. Therefore, the widely reported low density and often richness of native plants in invaded communities cannot be directly linked to ecosystem susceptibility to invasion without considering concomitant impacts. These findings suggest that density is a key preliminary determinant or factor which should be considered when assessing tree invasion dynamics.


Density Invasive impact Invasibility Meta-analysis Native community 


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© Akadémiai Kiadó, Budapest 2019

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Authors and Affiliations

  1. 1.Université de Toulouse, UPS, ENFA; UMR5174 EDB (Laboratoire Évolution et Diversité Biologique)ToulouseFrance
  2. 2.CNRSToulouseFrance
  3. 3.UMR BIOGECOUniversity of Bordeaux - INRA, Bat B8TalenceFrance
  4. 4.Department of BiologyYork UniversityTorontoCanada

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