Current Research on Geography, Earth Science and Environment Vol. 7

Macrophytes constitute a fundamental structural and functional component of aquatic ecosystems, playing a critical role in maintaining ecological integrity and biogeochemical processes. Variations in the abundance, distribution, and species composition of macrophyte communities often serve as sensitive indicators of environmental change. Despite several studies on aquatic macrophytes in freshwater ecosystems, existing research has largely focused on isolated aspects such as phytosociology, biomass, or physico-chemical characteristics. However, there is a lack of comprehensive, site-specific quantitative assessments integrating multiple ecological indices (frequency, density, abundance, abundance by frequency (A/F) ratio, and importance value index (IVI) for many wetlands, particularly in northeastern India. Therefore, the present study has been undertaken in Lake Kharungpat, situated in Manipur state, India. The primary objective of the study is to evaluate the quantitative characters of the aquatic macrophytes, viz., frequency, density, abundance, A/F ratios and importance value index IVI.  The lake was divided into four study sites, represented as Site I, II, III and IV, which are locally named as Panchao, Pangalpat, Kambong Leiram and Kharungpat Khong, respectively. The aquatic macrophytic plant samples were collected at regular monthly intervals during the period January, 2008 to December, 2009 from the study sites. The statistical analysis was carried out by using SPSS Ver-20, and the statistical tools like ANOVA (Analysis of Variance) and Box Plot techniques were used for interpretation of the findings.  During the whole study period, a total of 54 macrophytic plant species belonging to 28 families were found distributed in the lake. The aquatic plant species recorded were grouped into different categories, viz., submerged (7 species), rooted with floating leaves (6 species), free floating (8 species) and emergent (33 species) respectively. Alternanthera philoxeroides, Azolla pinnata, Brachiaria mutica, Ceratophyllum demersum, Echinochloa stagnina, Eichhornia crassipes, Enhydra fluctuans, Hygroryza aristata, Ludwigia adscendens, Pistia stratiotes, Salvinia cucullata and Zizania latifolia were the dominant species found to occur in all the study sites during the entire study period. The maximum frequency was exhibited by Echinochloa stagnina (85%), whereas the maximum density value was shown by Ceratophyllum demersum (213.60 plants m^–2). The highest abundance value was exhibited by Echinochloa stagnina (506.67 plants m^–2). The higher ranges of A/F ratios were reported in some species, viz., Alternanthera philoxeroides (0.44), Echinochloa stagnina (0.42), Azolla pinnata (0.38), etc. Alternanthera philoxeroides (42.41) recorded peak value of importance value index (IVI). The analysis of variance (ANOVA) for all the aquatic macrophytes reported from the lake indicates that there is no significant variation within the four study sites in terms of distribution. However, the F-test result indicates significant variation in the quantitative characters between the different macrophytic plant species of the lake. The analysis was primarily based on short-term field observations and does not capture long-term ecological trends. In future, long-term monitoring programs should be conducted to assess seasonal and interannual variations in macrophyte communities.