Assessment of Carbon Stock in Association with Nutrient Content in the Littoral Zone of Kalchuman Lake of Manaslu Conservation Area
Carbon stock is the quantity of carbon contained in a ―pool‖ and lakes are considered to be the potential sink of carbon dioxide. But, despite of the potentiality, their role as carbon sequester is not clearly known in case of Nepal yet. Additionally, variability of carbon sequestration with reference to nutrients in wetlands is also attracting more attention. Thus, the study was carried out to assess carbon stock and its association with nutrient content in the high altitude lake (3690 m) i.e. Kalchuman Lake of Manaslu Conservation Area. Along with it, the morphometric and catchment characteristics were also studied.
For the study of morphometric and catchment characteristics, georeferenced map of the study area was used with Arc GIS. And systematic random sampling method was used for sampling of 10 samples of water, 20 samples of sediments (10 from littoral zone and 10 from bank), 10 samples of macrophytes and 10 samples for litters. Then the carbon content and nutrient content were determined by the standard lab methods given by APHA (1995), Trivedy & Goel (1986), Jackson (1973) and Motasara & Roy (2008). Finally Pearson correlation and multiple regression analysis were done using SPSS to determine the relationship between carbon and nutrient content in water and sediment samples.
From the morphometric and catchment characteristic analysis it was found that the lake was not completely circular and its catchment area was found to be dominated by grasslands. The carbon stock in water, soil, macrophytes and litters of the lake were 15.57±5.9 mg/l, 23.56±8.29 ton/ha, 0.04 ton/ha and 0.18 ton/ha respectively which showed that among all components, soil was the highest storehouse of carbon. Though, carbon storing capacity of soil varied with the texture.
The concentration of nutrients in the lake was found to be lower in comparison to the lakes at lower altitude (Rara 2990m) and higher than that of higher altitude lakes (Tilitso 4690m and Gokyo 4750m). However, the correlation and regression analysis depicted the nitrogen as the factor with the highest predictive capacity for carbon.
Thus, the lake was found to be significant storehouse of carbon though its relationship was stronger with nitrogen content. Hence, conservation of lakes is necessary and lakes should also be enrolled in the CDM mechanism to mitigate the climate change.