Intense livestock grazing outcompetes wild-ungulates in low-productivity rangelands. This is a long-standing and highly debated conservation problem globally. We examined impacts of migratory livestock grazing on Trans-Himalayan rangeland and Asiatic ibex, a wild-ungulate and primary prey of the endangered snow leopard. Vegetation and ibex were sampled in an intensely grazed (livestock density 63 sheep-goat/km2) and ungrazed areas, during spring (before-grazing), summer (during-grazing) and autumn (after-grazing). Proportionate to vegetated area, independent randomly laid 1mX1m plots were sampled for vegetation cover and biomass estimation (Cover: NUngrazed=237; NGrazed=127; Biomass: NUngrazed=119; NGrazed=64). Ibex density and young:adult-female ratios were estimated by repeatedly sampling 17 trails using double-observer method across both treatments for the three time periods and two consecutive years. Graminoid and herb biomass were significantly higher in ungrazed than grazed area (ANOVA; Graminoid: FTreatment=16.05; P=<0.001; Herb: FTreatment=22.75; P=< 0.001). Overall vegetation composition was dissimilar across ungrazed and grazed area (Morisita Index 0.18), however, palatable species composition was similar (Morisita Index 0.70). Biomass of palatable species was 2.25 times higher in ungrazed than grazed area. Total off-take of dry forage by migratory livestock from grazed pastures (61 km2) was 10,658 kgs km-2 over two months of grazing. Ibex density was 1.80-7.0 times higher in ungrazed than grazed area in 2015, while 2.45-4.7 times higher in ungrazed than grazed area during 2016. Ibex yearling:adult-female ratio was six times higher in ungrazed than grazed area. Significant reduction in forage availability lowered ibex density and yearling:adult-female ratios in grazed area, suggesting migratory livestock outcompetes ibex through exploitative competition.
Migratory livestock grazing significantly impacts rangeland vegetation and wild-ungulate population in the Indian Trans-Himalaya
12th International Mammalogical Congress, 2017. Perth, Australia