Effect of climate change on potential distribution of Dactylorhiza hatagirea (D. Don) Soó in the twenty-first century across the north-western Himalayas

The populations of Dactylorhiza hatagirea are shrinking fast across the north-western Himalayas. Although the effects of contemporary anthropic factors on its distribution are well documented, the impacts of anticipated climate change have not been evaluated. In the present study, the maximum entropy modelling (MaxEnt) was used to quantify the impact of climate change on the distribution of D. hatagirea over the next 50 years under representative concentration pathways (RCP) 4.5 and 8.5, using ensemble mean of four general circulation models, viz. CCSM4, CNRM, MRI, and GFDL. The results exhibited a fairly good model performance, with D. hatagirea attaining the highest suitability when ‘annual mean temperature’ and ‘annual precipitation’ peaks at ca. 11.5 °C and 1,250 mm, respectively. The variables with greater influence (%) were annual precipitation (40.7), mean temperature of the wettest quarter (22.9), precipitation seasonality (16.6), and mean annual temperature (10.4). Under the current climate, about 790 km² that spread across Kashmir (274.1 km2) Jammu (210.5 km²), and Ladakh (305.6 km²) were identified as high potential habitat (HPH) areas. The predicted distribution showed that for RCP 4.5 the HPH areas would decrease by 4.2 and 5.4%, by 2050 and 2070, while for RC P8.5 the decrease would be 18.1 and 8.7%, respectively. The shrinkage may be more obvious across tropical and temperate regions, while the species may gain new HPH areas across cold arid areas. Although HPH shrinkage for D. hatagirea appears mild, but as it exhibits high habitat specificity and grows inherently slow, this insignificant shrinkage may enhance its risk of local extinction. Therefore, an integrated approach involving in-situ measures across regions, where the species may disappear, and ex-situ measures, where it may expand, is hugely important.