Effects of Plant Diversity and Soil Properties on Above Ground Biomass in Altitudinal Gradient: A Case Study from Grassland of Mustang District, Nepal

Abstract

This research was conducted in Mustang district to see the effect of plant diversity and soil properties on aboveground biomass in altitudinal gradient. Above ground biomass estimation was done using various mathematical equations. Soil properties determination was done using calorimetric, Kjeldahl Dry-block method, feel method and core sampling methods. Simpson's Diversity Index and Shannon-Wiener's diversity index were used to study species diversity. Result shows that above ground biomass decreased with increase in altitude (R2 = 0.148). Above ground biomass increased with increase in species richness (R2= 0.1676). Lete-Kunjo site has high dominance of species than that of Kowang site accounting 23 and 12 respectively. Kobresia spp. has high IVI (91.134) followed by Carex spp. (52.178) in Kowang. Above ground biomass was found significantly higher on lower zone. Above ground biomass increased with increase in soil organic matter percentage (R2= 0.145). Above ground biomass increased with increase in soil nitrogen percentage (R2= 0.1607). Above ground biomass decreased with increase in soil pH (R2= 0.1393). There is positive linear relationship between above ground biomass and species richness. Soil Nitrogen and organic matter have positive linear relationship with above ground biomass but not with the soil pH. So to increase the aboveground biomass of grasslands and to protect the diversity of Mustang district, it necessary to conserve mountain grassland, especially in higher altitude zones, by protecting soil from erosion and landslides, and rotational grazing of livestock's for increasing soil organic matter.