Bambusa bambos (L.) Voss. alters Structure and composition of native forests: A study from moist evergreen forests in Sri Lanka

Abstract

Studies to evaluate consequences of native species showing invasive behaviour are rather scarce in the tropics. Bambusa bambos (L.) Voss., a native bamboo species, expands populations in its native range causing changes to the appearance of forests in dry and intermediate zones of Sri Lanka. The study evaluated the impacts of B. bambos spread in Tropical Moist Evergreen Forests (TMEFs) in Sri Lanka. A vegetation study was carried out in forest patches with and without bamboo (B+ and B-) from three study sites viz., Galboda (GAL), Moragolla (MOR) and Maragomuwa (MAR) located in the Intermediate Zone of the island. Six 100 m2 quadrats were eramarked at different distances from the forest edge towards the forest interior along three transects in each B+ and B-forest communities per site totaling 108 quadrats (2 forest communities B+ and B-× 3 transects × 6 distances × 3 sites = 108). Due to high site-specific differences, the results were analyzed and presented site-wise. Of the total of 127 species, 35 (27.6%) and 20 (15.7%) species were exclusively found in B+ and B-, respectively. The endemics were constantly more abundant in bamboo-free forest patches. The analyses also revealed a high dissimilarity of species compositions between B+ and B-forest communities. The mortality incidences were significantly greater in bamboo-forests, possibly due to frequent fires aided by high accumulation of light bamboo litter. Despite no consistent differences between B+ and B-communities in all study sites due to high heterogeneity, the results indicate that B. bambos has shown the potential to alter the composition and structure of these native forests through bamboo-driven modifications to micro-environmental conditions of these forests. Thus, the study highlights the importance of more comprehensive studies to explore long-term impacts of B. bambos in native forests in the region and to introduce measures to mitigate some of these negative impacts. The underlying causes of high mortality incidences should also be further investigated as it may leads to the decline of the quality of these native forests.