Novel ecosystems support substantial avian assemblages: the case of invasive alien Acacia thickets

作者：Rogers Andrew M^*; Chown Steven L

来源：Diversity and Distributions, 2014, 20(1): 34-45.

DOI：10.1111/ddi.12123

• Biological invasions
• body size
• conservation value
• local-regional assemblages
• novel ecosystems

AimAltered habitats may form entirely novel ecosystems that support new combinations of species. How indigenous species use invaded areas is, however, not well understood. Here, we investigate the value of Australian Acacia thickets as novel ecosystems in the Western Cape of South Africa by surveying bird assemblages within them. %26lt;br%26gt;LocationWestern Cape Province of South Africa. %26lt;br%26gt;MethodsBirds were surveyed quantitatively in a variety of Acacia thickets in the south-western Western Cape in three seasons to examine species richness, abundance and functional diversity. We also examined the extent to which avian diversity was related to differences in patch-level vegetation structure. %26lt;br%26gt;ResultsSignificant variation was observed in assemblage richness, density and biomass across sites. Diversity increased with productivity, but declined with stem density and canopy cover. On average, Acacia thicket patches were used by c.20 species (with a regional richness of 76 species), had a mean density of 7.78birdsha(-1) and a mean biomass of 0.224kgha(-1). The most abundant feeding guilds were the mixed feeders and insectivores. %26lt;br%26gt;Main conclusionAcacia thickets in the Western Cape support a large subset of the region%26apos;s birds with the most abundant species being small mixed feeders. Compared with other habitat types, Acacia thickets support avian assemblages with species richness and density similar to some natural sites in the region, but lacking typical nectarivores. Extrapolation to the area transformed by invasive acacias in the Cape Floristic Region suggests that these novel ecosystems support c.22 million individual birds or 621tonnes of avian biomass.

• 出版日期2014-1