Pastoralism in the highest peaks: Role of the traditional grazing systems in maintaining biodiversity and ecosystem function in the alpine Himalaya

Discussion Impact of grazing on species diversity and ANPP Studies from around the world show varied effects of grazing on vegetation [2,21,22,64–66]. A meta-analysis of sixty-one studies from the Tibetan plateau showed grazing mediated increase in species diversity but a decrease in above ground biomass [67]. In the Himalaya grazing has been shown to increase species richness under moderate grazing intensity [38,68,69]. The results of this study show an increase in species diversity indices in grazed areas. Species rich- ness in grazed areas increased around 90% in all elevations combined and doubled in the mid- dle and lower zone. In the higher zone species richness increased by 61.5%. Studies from the region show mixed results with respect to the impact of grazing on ANPP [38,69–71]. While Kala and Rawat’s [70] study in the Western Himalaya demonstrated a decrease in ANPP by 31% under grazing treatment, Bagchi and Ritchie [69] showed an increase of ANPP in the Fig 3. Non-metric Multidimensional Scaling (NMDS) based on Bray Curtis similarity matrix of plant communities. Analysis of similarity (ANOSIM) statistic R and its significance are indicated in boxes. Groups are represented by ellipses (95% CI around centroids). NMDS ordination of 153 species grouped according to grazing treatment (A) and elevation gradient (B); NMDS ordination of species in lower (C), middle (D), and higher elevation (E) zones respectively grouped according to grazing treatment. https://doi.org/10.1371/journal.pone.0245221.g003 PLOS ONE

Role of the traditional grazing systems in maintaining biodiversity and ecosystem function in alpine Himalaya PLOS ONE | https://doi.org/10.1371/journal.pone.0245221 January 7, 2021 9 / 19