Assessing Plant Species Distribution and Vegetation Structure in the Lake Chilwa Floodplain,Zomba, Malawi

Abstract

ABSTRACT The study aimed to explore the composition and distribution of plant species across the floodplain of Lake Chilwa, an endorheic shallow lake known for its significant fluctuations in water levels due to seasonal weather changes. The research used belt line transects, each measuring 150 m � 6 m, consisting of 18 plots, each sized 30 m � 6 m, across six sites with varied slopes, to sample remnant vegetation and collect soil samples to analyze physicochemical properties. Indicator species and classical clustering analyses identified plant communities; Shannon's (H) and Simpson's (1�D) diversity indices measured species diversity in distinct hydroperiod zones. Non-metric Multidimensional Scaling and Similarity percentage analysis identified species dissimilarity among sites. Correlation and Principal Component analysis determined soil properties relationships. The results found a total of 129 species, mainly herbs (50.4%), grasses (31%), and sedges (12.4%), with the Poaceae family being the most diverse. Three plant communities were identified, with one found in the permanently waterlogged zone showing the highest diversity indices and moderate nutrient levels. In general, the floodplain had a lower abundance of Cyperus papyrus and Phragmites australis than similar floodplains in Sub-Saharan Africa. The highest species dissimilarity (67.75%) was found between sites at higher and lower slopes. Oryza longistaminata A. Chev. & Roehr predominantly occurred in lower slope areas, while Typha domingensis Pers was distributed across all sites. Soil analysis revealed sand as the main constituent in the floodplain, with a significant positive correlation between potassium and pH and a significant negative correlation between potassium and magnesium. These findings suggested that the water regime and landscape features of Lake Chilwa influence species composition and distribution, as well as soil nutrient dynamics within the floodplain. Preserving natural water flow and minimizing human disturbances can enhance the ecosystem's resilience and biodiversity, thus key to conserving the ecosystem.

??????????????????????????????????????????????????????????????????????????????????? Chilwa ????????????????????????? ???????????????????????????????????? ???????????????????????? 150 x 6 ???? ?????????????????????????? 18 ???? ???? 30 x 6 ???? ?? 6 ??????????????????????????? ????????????????????????????????????????????? ?????????????????? ?????????????????????????????????-?????? ????????? ??? ???????????????????????????? classic cluster; ????????? ?????????????????????? ???Shannon's (H) ??? Simpson's (1�D) ?????????????????????????? ??????? Non-metric Multidimensional Scaling ?????????????????? Similarity percentage ??????????????????????????????????????????????????????? ??????????????????? Correlation and Principal Component ???????????????????????????????????????????????? ??????????????? 129 ???? ???????????????????? (?????? 50.4) ???? (?????? 31) ????? (?????? 12.4) ???????????? Poaceae ??????????????????????? ???????????????????????????? ?????????????????????????????????????????????????????? ??????????????????????????????????? ?? species dissimilarity (?????? 67.75) ?????????????????????????????????????????????????? ??? ??????????????? ???????????????????????? Oryza longistaminata A. Chev. & Roehr ??????????? ???? Typha domingensis Pers ?????????????? ?????????????????? ????? ?????????????????????????????????????????????????? ??????????????????????????????? ?????????? ??? pH ????? ???????????????????????? ??????????????????????? ??????????????????????????????????????????????????????????????????????Chilwa ????????????????????????????????????? ????????????????????????????????????????????????????????????????????????? ???????????????????????????????????? ??????????????????????????? ??????????????????????????????????????????????????????????????????????????????????????????