Novel ecosystems support substantial avian assemblages: the case of invasive alien Acacia thickets. Issue 1 (6th September 2013)

• Record Type: Journal Article
• Authors: Rogers, Andrew M.; Chown, Steven L.; Richardson, David
• Is Part Of: Diversity & distributions. Volume 20:Issue 1(2014:Jan.)
• Page Start: 34
• Page End: 45
• Publication Date: 2013-09-06
• Subjects: Biodiversity -- Periodicals; Biodiversity conservation -- Periodicals; 577
• DOI: 10.1111/ddi.12123
• Languages: English
• ISSNs: 1366-9516

Abstract

<abstract abstract-type="main" id="ddi12123-abs-0001"> <title>Abstract</title> <sec id="ddi12123-sec-0001" sec-type="section"> <title>Aim</title> <p>Altered 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 <italic>Acacia</italic> thickets as novel ecosystems in the Western Cape of South Africa by surveying bird assemblages within them.</p> </sec> <sec id="ddi12123-sec-0002" sec-type="section"> <title>Location</title> <p>Western Cape Province of South Africa.</p> </sec> <sec id="ddi12123-sec-0003" sec-type="section"> <title>Methods</title> <p>Birds were surveyed quantitatively in a variety of <italic>Acacia</italic> 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.</p> </sec> <sec id="ddi12123-sec-0004" sec-type="section"> <title>Results</title> <p>Significant 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, <italic>Acacia</italic> thicket patches were used by <italic>c</italic>. 20 species (with a regional richness of 76 species), had a mean density of 7.78 birds ha<sup>−1</sup> and a mean biomass of 0.224 kg ha<sup>−1</sup>. The most abundant feeding guilds were the mixed feeders and insectivores.</p> </sec> <sec id="ddi12123-sec-0005" sec-type="section"> <title>Main conclusion</title> <p> <italic>Acacia</italic> thickets in the Western Cape support a large subset of the region's birds with the most abundant species being small mixed feeders. Compared with other habitat types, <italic>Acacia</italic> 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 <italic>c</italic>. 22 million individual birds or 621 tonnes of avian biomass.</p> </sec> </abstract>