Ensemble modelling under multiple climate change scenarios predicts reduction in highly suitable range of habitats of Dactylorhiza hatagirea (D.Don) Soo in Himachal Pradesh, western Himalaya

Abstract

• Ensemble modelling was utilized to determine potential suitable habitat range of Dactylorhiza hatagirea in Himachal Pradesh. • Ensemble of 08 different models and 05 GCMs was utilised to determine suitable future areas by years 2050 and 2070. • Suitable habitat range of D. hatagirea would be reduced by years 2050 and 2070, with conducive conditions towards east. • As per IUCN criterion A3(c), it will lose more than 30% of its current suitable habitat, can be categorized as Vulnerable. • Assisted colonization efforts in up to 7.39 new cells (2×2 km 2 size) are required to exclude it from threat category. Species distributions models (SDMs) are an indispensable and important tool for predicting suitable habitats and projecting the impacts of future climate change on habitat distribution of species, particularly the threatened species. Amongst such species, Dactylorhiza hatagirea (D.Don) Soo is a threatened, medicinal orchid endemic to Himalaya. In the present study, we utilized ensemble modelling to identify the current potential suitable habitats and predict the impacts of future climate change on the distributional range of D. hatagirea in Himachal Pradesh, an Indian State in Western Himalaya . An ensemble of eight different model was run on non-collinear bioclimatic and topographic variables to predict its current potential distribution. A further ensemble of five global circulation models, focusing on four representative concentration pathways, was utilised to select the suitable habitats in future, for the years 2050 and 2070. The main bioclimatic variables influencing the predictions of potential distribution of D. hatagirea were Mean Temperature of Warmest Quarter (Bio10), Isothermality (Bio3), Mean Temperature of Wettest Quarter (Bio8), Slope, Precipitation Seasonality (Bio15) and Mean Diurnal Range (Bio2). The results of ensemble model revealed that, under present climatic conditions, the potential current suitable habitats of D. hatagirea comprises of only 0.09% of the study region. The model predicted that compared to the current distribution, the highly suitable habitats, under various future climate scenarios, would be significantly reduced by 25.34% to 56.34% and from 22.54% to 38.03% by the years 2050 and 2070 respectively. Our study also showed that the centroid of suitable habitats of D. hatagirea will shift towards eastern side of Himachal Pradesh. As per IUCN range loss criterion A3(c), D. hatagirea would lose more than 30% of its currently occupied suitable habitat, and this can be categorized as ‘Vulnerable’. Therefore, an assisted colonization (AC) would be required in 0.21 to 5.98 and 0.56 to 7.39 new cells (each of grid size 2×2 km 2 ) for the years 2050 and 2070 respectively, to halt the range loss below the threshold of 30% and shift it to the ‘Least Concern’ category. Further, it was found that the availability of suitable cells within existing network of protected areas (PAs) in the region are adequate and could be a better alternative to achieve conservation goals through AC. In the present study, we found that the habitats of D. hatagirea in western Himalaya are extremely vulnerable to future shifts and alterations in the climate patterns. The findings from the present study, thus, could be utilized to alleviate the threats to the survival of populations of this species by carrying out activities such as protecting the habitats, studying the unexplored populations, re-wilding and AC programmes within the PAs, for planning of conservation and management strategies.

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