Floristic composition, diversity, and spatial variation of lakeshore grassland vegetation in Barangays San Antonio and Tagumpay, Bay, Laguna, Philippines

Abstract

Lakeshore grasslands are important components of freshwater ecosystems, providing habitat for wildlife, forage resources, shoreline protection, and other ecosystem functions. Although these ecosystems contribute substantially to biodiversity conservation and ecosystem functioning, studies describing their vegetation composition and diversity remain scarce in many tropical regions. This knowledge gap is particularly evident along the shores of Laguna de Bay, where information on lakeshore vegetation remains limited. This study aimed to characterize the floristic composition, diversity, and spatial variation of lakeshore grassland vegetation in Barangays San Antonio and Tagumpay, Bay, Laguna, Philippines. Vegetation sampling was conducted in August 2025 using nested quadrats established along five transects. Twenty-eight quadrats were surveyed and aggregated into seven sampling stations across two barangays. Species diversity was evaluated using the Shannon–Wiener Index, Simpson’s Diversity Index, and Pielou’s Evenness Index. Thirty-five plant species across 18 genera and 10 families were documented. Poaceae was the most represented family and formed the structural backbone of the vegetation community. The vegetation was largely composed of widespread, disturbance-tolerant taxa. The grass species Brachiaria mutica, Sorghum halepense, and Echinochloa crus-galli exhibited the highest importance values and contributed substantially to overall vegetation cover and density. Several introduced and invasive species, including Lantana camara, Cyanthillium cinereum, and Commelina diffusa were recorded across multiple sampling sites. Species diversity was generally moderate (H′ = 2.10–2.32), while spatial analyses revealed localized variation in species composition and diversity among sampling stations, with no significant spatial autocorrelation. The findings provide baseline information for future monitoring, conservation planning, and management of lakeshore vegetation in Laguna de Bay and contribute to a better understanding of plant community dynamics in disturbed tropical lakeshore ecosystems.