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The threat from non indigenous species - ecosystem vulnerability, global distribution and co-occurrence with other major threats

  • Helena Berglund
Publiceringsår: 2009
Språk: Engelska
Sidor: 100
Dokumenttyp: Doktorsavhandling


We live in a globalised world where people and goods travel large distances. Various species are brought along on these journeys, intentionally or as hitchhikers. Some of these species establish populations in regions to which they could not have spread without human assistance, and where they are considered to be non indigenous species (NIS). These species can affect the ecosystem in the recipient region by species interactions and altering abiotic factors. Only a small part of the introduced species will cause problems in the recipient region. However, a vast number are introduced, and NIS have become a matter of large concern since they can cause loss of biodiversity. To prevent damage with as little interference with other interests, e.g. trade, as possible, attempts to identify characteristics of invasive NIS, and ecosystems heavily invaded by these, have been made. Since impact from NIS is difficult to assess, many studies have instead focused on the abundance or rate of spread of invasive NIS. This can be misleading since other threats to indigenous species diversity can facilitate the spread of NIS. Introduced species can thus become abundant without actually having an impact on indigenous species. When trying to identify characteristics of recipient regions which make them vulnerable it is therefore important to assess the impact of NIS.
In this thesis I explore different aspect of ecosystem vulnerability to NIS. I have taken a global perspective and used data from global databases to derive methods to estimate vulnerability but I have also worked with regional data from ponds in southern Sweden. I found that species with small distribution ranges appear to be sensitive to NIS and ecosystems with many such species can be vulnerable. NIS on the other hand appear to have larger indigenous distribution ranges than species in general. I also investigated co-occurrence between the threat from NIS and other major threats against global biodiversity and the spatial distribution of elevated vulnerability to the different threats. The threat from NIS was associated with some, but not all, other threats. Species threatened by natural disasters or change in indigenous species dynamics were for example more likely to also be threatened by NIS than species in general. North America and Oceania appeared vulnerable to NIS but not to other threats, which other land regions were vulnerable to. South and Southeast Asia and Sub-Saharan Africa, both low in gross domestic product (GDP) per capita, where for example vulnerable to biological resource use. Europe was vulnerable to 5 of the 12 threats included, more than any other region, of which all were human induced and the vulnerability may be a consequence of high exposure due to the high population density and GDP per capita.


Blå hallen, Ekologihuset, Sölvegatan 37, 22362 Lund
  • Mark Williamson (Professor emeritus)


  • Ecology
  • threats
  • distribution range
  • isolation
  • endemism
  • invasions
  • invaders
  • vulnerability
  • non indigenous species
  • rarity
  • threatened species


  • Göran Bengtsson
  • Johannes Järemo
  • ISBN: 978-91-7105-301-5

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