Incorporating plant phenological responses into species distribution models reduces estimates of future species loss and turnover

Impacts of climate change on the distribution pattern of Himalayan Rhubarb (Rheum australe D. Don) in Nepal Himalaya

While there has been substantial consensus that climate change poses a severe threat to the Himalayan biota; we still lack comprehensive data on the potential impact of climate change on the important Himalayan medicinal plants connected with the livelihood of local people and the national economy. In this study, using MaxEnt, we modelled the distribution pattern of Rheum australe, a medicinal plant prioritized by the Government of Nepal for the nation's economic prosperity, for the current as well as all four future projections (SSP126, SSP245, SSP370, and SSP585) to all the data available periods (2021-2040, 2041-2060, 2061-2080, and 2081-2100). In addition, we performed spatial overlay analysis to identify the optimum zones that could be developed as potential planting/conservation sites for R. australe in any of the projected future climate scenarios. Our results revealed that the suitability area of R. australe is expected to contract in all the scenarios and periods with a significant loss expected to occur in SSP585 for 2081-2100. On the individual district level, northwestern districts are expected to have a huge loss of suitable habitats in the future, while four districts: Jumla, Kalikot, Dolpa, and Jajarkot of the Karnali Province are expected to gain suitable habitats remarkably. Therefore, we suggest that the forests and rangelands of the four districts at an elevation range of 3300 m - 4,400 m could be developed as potential planting areas for commercial cultivation/for establishing genetic resource conservation centres. This finding thus has wider policy implications for both government and conservation organizations.

Future climate change facilitates the herb drought-tolerant species distribution than woody species

Drought-tolerant species play a crucial role in maintaining ecosystem services in arid and semi-arid regions wherein subject to rapid climate change. However, how future climate change affect the distribution of drought-tolerant plants with different growth forms (e.g., herb and woody) remains largely unknown. Here, we used the MaxEnt model to simulate the potential species distribution under current conditions, and predicted the future species distribution of 82 common drought-tolerant plants in China under two time periods (2041-2060 and 2081-2100) and three climate change scenarios (SSP126, SSP245 and SSP585) in the future. We found that the western and northern regions of China are hotspots for drought-tolerant plant distribution. Compared with other predictors, aridity index (AI) explained the largest portion of variation (45%) in the distribution patterns of drought-tolerant plant plants. Climate change would change the distribution of drought-tolerant plants, with more than 50% of the species showing a trend of shrinking ranges in China. For both herb and woody plants, the highest turnover values were observed under SSP585 for the period 2081-2100, reaching 37.67% and 29.08%, respectively. Our results highlighted that herb and woody plants respond differently to climate change stresses, with herb plants projected to greatly expand their ranges in the future. These insights are vital for evaluating the impacts of climate change on biodiversity and informing the development of effective adaptation strategies.

The ecology of plant extinctions

Extinctions occur when enough individual plants die without replacement to extirpate a population, and all populations are extirpated. While the ultimate drivers of plant extinctions are known, the proximate mechanisms at individual and population level are not. The fossil record supports climate change as the major driver until recently, with land-use change dominating in recent millennia. Climate change may regain its leading role later this century. Documented recent extinctions have been few and concentrated among narrow-range species, but population extirpations are frequent. Predictions for future extinctions often use flawed methods, but more than half of all plants could be threatened by the end of this century. We need targeted interventions tailored to the needs of each threatened species.