Suitability of Habitats in Nepal for Dactylorhiza hatagirea Now and under Predicted Future Changes in Climate

Abstract

Dactylorhiza hatagirea is a terrestrial orchid listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and classified as threatened by International Union for Conservation of Nature (IUCN). It is endemic to the Hindu-Kush Himalayan region, distributed from Pakistan to China. The main threat to its existence is climate change and the associated change in the distribution of its suitable habitats to higher altitudes due to increasing temperature. It is therefore necessary to determine the habitats that are suitable for its survival and their expected distribution after the predicted changes in climate. To do this, we use Maxent modelling of the data for its 208 locations. We predict its distribution in 2050 and 2070 using four climate change models and two greenhouse gas concentration trajectories. This revealed severe losses of suitable habitat in Nepal, in which, under the worst scenario, there will be a 71–81% reduction the number of suitable locations for D. hatagirea by 2050 and 95–98% by 2070. Under the most favorable scenario, this reduction will be 65–85% by 2070. The intermediate greenhouse gas concentration trajectory surprisingly would result in a greater reduction by 2070 than the worst-case scenario. Our results provide important guidelines that local authorities interested in conserving this species could use to select areas that need to be protected now and in the future.

Predicting the potential distribution of Dactylorhiza hatagirea (D. Don) Soo-an important medicinal orchid in the West Himalaya, under multiple climate change scenarios

“…Such factors play a key role in the alpine biodiversity where the species are skewed more towards particular habitats (i.e., moist and marshy habitat) than open grasslands or rugged terrains [14,49]. Previous findings are in line with this study, wherein altitude and bioclimatic variables (temperature and precipitation) were reported to play a major role in the distribution and population structure of D. hatagirea [50][51][52][53]. Among these, Thakur et al ( 2021) [52] reported…”

“…Climate warming and shifting of species towards north/ northeast in the Himalayas is reported [3,35,71,72]. In Nepal, Shrestha et al (2021) [53] projected that the target species would be elevated to 5000 m in the future, a substantial change when compared with the present distribution at 4000 m. A similar prediction for the species has been made elsewhere [3,50].…”

“…Blinova (2008) [55] and Sletvold et al ( 2010) [56] have shown that temperature (of the growing season) and precipitation are responsible for the persistence of Dactylorhiza populations. Further, a study by Shrestha et al ( 2021) [53] from Nepal postulated a different stance where annual mean temperature (Bio1), precipitation seasonality (Bio15), and annual precipitation (Bio12) are the most significant variables in the target species distribution, while, precipitation in the coldest quarter (Bio19), precipitation in the driest quarter (Bio17), and the environmental layer were of intermediate significance. Similar to our findings, Rana et al (2020) [3], using ensemble species distribution modelling (eSDM), reported elevation (30.97%) as the major dominant contributing variable, while amongst the bioclimatic variables, the mean temperature of the wettest quarter (Bio 8; 24.69%) and annual precipitation (Bio12; 21.11%) were the key contributing variables.…”

“…In addition to the above, soil type, moisture ratio, and soil pH [49] are the other vital decisive variables that posture or play a role in shaping the distribution of D. hatagirea (Table 3). In a study by Thakur et al (2021) [52] revealed that the populations of D. hatagirea flourished in soils rich in organic matter (i.e., loamy sand to sandy loam) and had adequate soil moisture [53] emphasized geological substrate and soil properties to be the key factors determining the distribution of the species. Similar observation was recorded during our ecological assessment surveys wherein the target species has luxuriant growth in moist sites along the hill slopes, dodged within narrow streams, and on open undulating meadows with high soil moisture [49].…”

Illegal harvesting and livestock grazing threaten the endangered orchid Dactylorhiza hatagirea (D. Don) Soó in Nepalese Himalaya

“…Inherently slow growth, high habitat specificity, dependency on pollinators, need of mycorrhiza for reproduction and germination, narrow range of ecological substitution options, unsustainable exploitation, and climate change are major challenges for the growth and development of orchids, such as Dactylorhiza hatagirea (Dhiman et al, 2019;Hinsley et al, 2017;Hutchings et al, 2018;Rasmussen & Rasmussen, 2018;Reiter et al, 2017;Shrestha et al, 2021;Yeung, 2017). Due to a marked decline in its natural populations, D. hatagirea has been listed as an endangered species in Nepal by Conservation Assessment and Management Plan (Bhattarai et al, 2001).…”