# Impact of Climate Change on the Narrow Endemic Herb Psilopeganum sinense (Rutaceae) in China

## TL;DR

This study examines how climate change affects the narrow endemic herb Psilopeganum sinense in China, predicting significant habitat loss and fragmentation.

## Contribution

The study uses the random forest algorithm to model the long-term effects of climate change on the distribution of Psilopeganum sinense.

## Key findings

- Precipitation seasonality and mean diurnal range are the main climatic variables limiting the current distribution of P. sinense.
- Future climate scenarios predict a 32.84% decrease in suitable habitats for P. sinense by the 2050s under RCP4.5.
- Historically, P. sinense had a broader and more continuous distribution compared to its current fragmented pattern.

## Abstract

Psilopeganum sinense is a perennial herb endemic to the Three Gorges Reservoir Area (TGRA) of the Yangtze River and its surrounding regions. This species is crucial for ecological conservation and regional socioeconomic development. Recent extreme weather events in the TGRA have directly and indirectly caused local losses of numerous wild populations of
P. sinense
. Given the severe survival crisis induced by climate change, it is essential to explore the effects of climate change on the potential distribution of
P. sinense
. Although there is a general awareness of the adverse effects of climate change on various species, there is a lack of comprehensive studies focusing on the long‐term effects and detailed climatic variables influencing the distribution of
P. sinense
. In this study, we aimed to use the random forest (RF) algorithm to analyze the redistribution of
P. sinense
across several critical climatic periods. The results indicated that the main variables limiting the present geographical distribution of
P. sinense
were precipitation seasonality and the mean diurnal range. Currently,
P. sinense
is mainly distributed in the riparian zone of the TGRA and its surrounding areas, exhibiting a relatively narrow climatic niche and habitat fragmentation pattern. Historically, distributions under past climatic conditions were relatively intact and more extensive than the current distribution area. During the last interglacial period, a broad distribution of highly suitable areas was observed in eastern Sichuan Province, northern Chongqing, and central Hubei Province, exhibiting a continuous distribution pattern. Future climate scenarios indicated a projected 32.84% decrease in suitable areas under RCP4.5–2050s. In northern Chongqing, the ecological corridors established in highly suitable habitats would fragment and gradually separate. Some previously unsuitable areas for
P. sinense
could transform into potentially suitable habitats because of climate change; however, these suitable areas might exhibit fragmented and discrete distribution patterns. In general, both the shrinkage of suitable habitats and habitat fragmentation would compress the already limited survival space of P. sinense, leading some populations to prematurely confront critical survival decisions under severe climate pressures. Our results not only provide a scientific basis for managing
P. sinense
resources in the context of climate change but also serve as an important reference for restoring wild
P. sinense
populations.

Psilopeganum sinense is a perennial herb endemic to the Three Gorges Reservoir Area (TGRA) of the Yangtze River and its surrounding regions. This species is crucial for ecological conservation and regional socioeconomic development. However, the indeed fact that the TGRA has experienced significant extreme weather events in recent years has directly and indirectly caused the local loss of many wild populations of
P. sinense
. Therefore, our results can not only provide a scientific basis for the management of
P. sinense
resources in the context of climate change, but also provide an important reference for the restoration of wild populations.