Koijam K.K. Mani Bhushan Singh
Abstract
The traditionally followed community ponds (ââ¬ÅLeikai pukhriââ¬Â) in Manipur have much significance on the fact that they are purely rain water harvest structures, but continued to have water all through the year. These traditional water reservoirs (TWRs) provide a suitable habitat for the growth of macrophytes. Macrophytes play a crucial role in the functionality of aquatic ecosystems. Given the ecological significance of Macrophytes in in treatment of traditional water reserviors, this current study was conducted by selecting three urban sites for a comparative analysis. A detailed investigation of net primary productivity was carried out on monthly intervals throughout the period of one year. The monthly net primary productivity in site I varied from minimum of 0.1 g m-2 month-1 (Salvinia cucculata) to maximum of 101 g m-2 month-1 in Alternanthera philoxeroide. The annual NPP of the different species varied from 2.6 g m-2 yr-1 (Azolla pinnata) to 278 g m-2 yr-1 in Alternanthera philoxeroides. It was found that the values of monthly NPP ranged from minimum (0.1 g m-2 month-1) in Lemna perpusilla to maximum (323.2 g m-2 month-1 in Eichhornia crassipes in site II. But the annual NPP of different species varied from 0.7gm-2 yr1 in Lemna perpusilla to 425.2 g m-2 yr-1 in Eichhornia crassipes. The site III exhibit monthly NPP ranged from minimum (0.2 g m-2 month-1) in Salvinia cucculata to maximum (33.1 g m-2 month-1) in Eichhornia crassipes in site III. The annual NPP values of different species varied from minimum (0.3 g m-2 yr-1 in Lemna perpusilla to (69.7 g m-2 yr-1) in Pistia stratiotes. The total annual NPP of all species was recorded 224. g m-2 yr-1 which is far less than that of site-I (408.8 g m-2 yr-1) and site-II (580.2 g m-2 yr-1). It is clear from the result that the maximum NPP were observed during monsoon in both site-II and site-III. But in site-I, the maximum productivity was found in retreating monsoon. The minimum NPP was observed during winter season in all the study sites.