The effect of the surrounding landscape matrix on mangrove bird community assembly in north Australia

• Published in: Biological conservation Vol. 144; no. 9; pp. 2134 - 2141
• Main Authors: Mohd-Azlan, J., Lawes, Michael J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2011; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; birds; Brackish water ecosystems; Co-occurrence; Communities; community structure; Compensation; Conservation; Conservation, protection and management of environment and wildlife; Density; Density compensation; Ecology; ecosystems; Fundamental and applied biological sciences. Psychology; Habitats; landscapes; Mathematical models; Matrices; Matrix effect; monsoon season; Nestedness; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; rain forests; savannas; species diversity; Species saturation; Species–area relationship; Synecology; Australia; Oceania; Matrix effect; Density compensation; Species saturation; Species–area relationship; Co-occurrence; Nestedness; Landscape; Species area relationship; Species-area relationship; Density; Vertebrata; Animal community; Mangrove; Nested subset; Compensation; Aves; Species richness; Environmental protection
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2011.04.003

► We examined the ecological determinants of bird community assemblage in mangroves of the Darwin region, North Australia. ► Mangrove patches did not comprise nested species subsets and large mangrove patches supported few species. ► No deterministic assemblage structure or density compensation suggests a weak competition effect on assemblage structure. ► However, species in the surrounding habitat accounted for ∼45% of bird species in a mangrove patch. ► Mangrove patches should be conserved as part of a habitat mosaic, including smaller patches rather than just big ones. Mangroves are highly threatened ecosystems yet their community ecology is poorly understood. We examined the ecological determinants of bird community assemblage in floristically depauperate mangroves. Birds were surveyed using line transect methods. Large mangrove patches supported fewer species than smaller patches. Patches did not comprise nested species subsets and the bird species richness of several small patches combined was greater than a single large area. The number of mangrove dependent species in a patch was area-dependent suggesting these species may be resource limited, although there was no species density compensation. There was a clear effect of the surrounding habitat, with matrix species accounting for ∼45% of bird species in a patch. Patches surrounded by tropical savanna were relatively species-poor, while regardless of size, patches including monsoon rainforest were relatively species rich. Null model analysis of non-random assemblage structure (nestedness and species co-occurrence) revealed no deterministic structure to the overall mangrove species assemblage. These analyses described a random pattern of bird distribution and with no evidence of density compensation this suggests that competition is a weak structuring force of mangrove bird assemblages. The lack of nestedness and the random co-occurrence of species are consistent with the matrix-dependence of bird community composition. Conservation plans should treat mangrove patches as part of a habitat mosaic and incorporate many smaller mangrove patches rather than just big ones. Consideration of the nature, extent and diversity of the surrounding matrices is vital in managing and conserving mangrove bird communities.