Effect of summer livestock grazing on plant species richness and composition in the Himalayan rangelands

Abstract

Grazing systems in the high Himalayas are changing in response to socioeconomic factors and policy decisions. As well as effects on livelihood of herders, such changes may have significant impacts on plant species richness and composition. The objectives of this study were to explore how plant species richness and composition respond to livestock grazing in the high Himalayan rangelands. The study was conducted in three mountainous Protected Areas of Nepal viz. Sagarmatha (Mt Everest) National Park, Gaurishankar Conservation Area and Khaptad National Park. Species and environmental data were collected along perpendicular transects outwards from goths (semi-permanent stopping and camping points). It was found that the distance from goths generally represents a grazing disturbance gradient. The core areas near goths had low species richness per plot (α-diversity) where nitrophilous and grazing-tolerant species were commonly found. However, the highest species richness, total numbers of species and occurrences of rare species at mid- and farther distances from goths within 800 m suggest that negative effects of summer livestock grazing were small and confined to limited areas near goths. Altitude, soil moisture content, percentage shrub cover and distance from goths were the variables significantly correlated with species composition, although the relative importance of these factors varied across study sites. This research can be used to inform decision-making about seasonal livestock grazing in the Himalayan rangelands, which should incorporate both ecological as well as socioeconomic considerations.