Past and future distribution pattern of Myrica esculenta in response to climate change scenario

Abstract

The structure and functions of an ecosystem particularly species composition and their distribution are expected to be altered with changing climate, and sustainability can be understood by investigating some key stone species. Myrica esculenta is an important medicinal tree of northwestern Himalayas, naturally occurring in hilly regions of northern India, southern Bhutan and western Nepal. In the current study, the species was modeled to estimate its potential distribution pattern under past [late interglacial (LIG), paleoclimate, last glacial maximum (LGM)] and future climate change scenarios of the representative concentration pathways (RCP 2.5–8.0) for 2050 and 2070, using Maximum Entropy (MaxEnt) algorithm. Overall, out-off 1022 geo-tag locations, 450 well distributed species presence points were used to run the model, of which 70% was used for training and rest 30% for validation. The performance and accuracy of the model were checked through an area under curve (AUC) which ranged from 0.846 ± 0.053 (LGM) to 0.924 ± 0.057 (LIG). Among all 9 bioclimatic variables, only 4 viz. temperature seasonality (Bio 4), mean temperature of wettest quarter (Bio 8), precipitation of driest month (Bio 14) and precipitation of warmest quarter (Bio 18), were contributed significantly (75.85%) to all the models used for prediction mapping. The highest 37.73% gain was observed for RCP 4.5_70 from the predicted map, and the future distribution coincided mainly between the districts Almora, Pauri, Chamoli and Bageshwar. Although the current suitable climatic habitat is located in northwestern Almora, the centroid expressed a tendency to shift south-eastward under all the four scenarios of RCPs. Furthermore, the centroid of the climatic habitat suitability will shift maximally 4.39 km southeast under RCP 6.0_2050. By the 2070s, the centroid will shift 3.46 km south-eastward under RCP 2.6. Maxent results revealed an increase in the area of environmentally suitable habitats for M. esculenta in northwestern Himalayas, if there is no anthropogenic pressure and evolutionary change occurs in the natural zone of distribution. This research provided past existence of the species and future climatic indications for enhanced distribution, besides suggesting academically for the conservation, protection, management, and sustainable utilization of M. esculenta resources.