Assessing Tree Diversity and Vegetation Composition in Wet Lowland Rice Associated Eco Units in Pelawattha, Sri Lanka: A Comparative Study of Riceland Associated Homegardens, Kalavita, and Owita Systems

Abstract

Wet lowland Riceland-associated eco units in Sri Lanka represent sustainable agricultural landscapes that significantly benefit ecosystem restoration by establishing high biodiversity and biomass. This study aimed to analyze the vegetation composition, structure, and tree diversity of dominant paddy land associated agroecosystems in Pelawatta (WL1), Sri Lanka, focusing on Riceland-associated homegardens, Kalavita, and Owita systems. Ten samples were randomly selected from each eco unit. Plant species were identified, recorded, and classified based on uses, origin, and growth form, with tree species measured for diameter at breast height (DBH). The Shannon-Wiener Index was used to estimate tree diversity. A total of 187 plant species, including 23 tree species (260 trees), were identified in homegardens; 74 species, including 12 tree species (146 trees), in the Kalavita system; and 97 species, including 15 tree species (214 trees), in the Owita system. The Shannon-Wiener index values ranged from 1.77 to 2.32 (mean 2.00) for homegardens, 0.30 to 1.54 (mean 1.16) for Kalavita, and 1.12 to 1.67 (mean 1.44) for Owita. Results indicated that Riceland-associated homegardens exhibit the highest tree diversity. In conclusion, wet lowland Riceland-associated eco units in Sri Lanka harbor a diverse range of plant species, including exotic, native, and endemic varieties, contributing to rich agrobiodiversity. This highlights the ecological and agricultural value of these traditional farming systems in promoting biodiversity and ecosystem resilience.