Avifaunal communities as indicators of silvicultural impacts in mangrove forests

Abstract

Although the Matang Mangrove Forest Reserve (MMFR) in Malaysia is suggested to be a global reference for sustainable silviculture, the impact of greenwood extraction on local biodiversity and ecological functionality remains under-researched. To fill this gap, a rapid biodiversity assessment was conducted using birds as ecological indicators to investigate the effect of mangrove silvicultural management on avian communities. Changes in the diversity of bird species and dietary guilds in response to forest age and management were assessed using the point-count method with visual and auditory observations. This was done in both "productive" forests, consisting of even-aged Rhizophora plantations producing poles and charcoal, and in "protective" forests where extractive activities are prohibited. Remarkably, all avifaunal functional guilds were present in both young "productive" and "protective" forests, however the "productive" forests supported fewer bird assemblages in terms of species richness and total taxonomic diversity compared to the floristically rich and structurally complex "protective" forests. The bird species' response to silvicultural disturbances also varied, with adverse effects especially occurring in functionally specialized species. Furthermore, back mangroves and transition zones to terrestrial forests were found to support a higher avifaunal diversity, possibly because of the enhanced habitat heterogeneity. Finally, this study highlights the use of bird communities as ecological indicators for assessing the quality of mangrove forests, and emphasises the crucial role of habitat and landscape heterogeneity in supporting diverse avifauna and ecosystem functionality highlighting the need for more research integrating mangroves and adjacent ecosystems.