Fern Communities in Lowland Tropical Forests of Brunei Darussalam, Borneo: Diversity, Indicator Species, and Environmental Drivers Across Forest Types

Ferns, as a large and biodiverse group, significantly contribute to the vascular plant diversity of the lowland tropical forests of Brunei Darussalam, Borneo. These forests encompass three main types: Mixed Dipterocarp Forest (MDF), Peat Swamp Forest (PSF), and Heath Forest (HF). This study aims to describe and compare fern communities in these three forest types, focusing on species richness, diversity, and the identification of indicator species. Additionally, it investigates the environmental factors that shape these communities. We conducted fieldwork in 48 plots across Brunei's lowland forests. We identified fern species and abundance through a visual census and analyzed environmental parameters, including soil pH, organic matter (OM) content, nutrient availability, and soil texture. The results showed 83 fern species, with MDF having the most (57 species). Peat Swamp and HFs had similar fern species richness (33 and 34 species, respectively). Our environmental analysis indicated that specific combinations of fern species and environmental parameters significantly correlate and effectively discriminate between the three forest types. Finally, we identified a selection of indicator species for each forest type. Our findings highlight the heterogeneity of Bornean lowland forests and the importance of preserving a diversity of habitats to maintain fern biodiversity. The study underscores the intricate interplay between environmental factors and fern diversity.