# From Glacial Refugia to Future Shifts: Unraveling the Spatiotemporal Dynamics of Endangered Acer sutchuenense Franch. Under Climate Change

## TL;DR

This study uses a MaxEnt model to predict the future distribution of the endangered Acer sutchuenense maple in China under climate change, highlighting the need for conservation strategies.

## Contribution

The study introduces a multi-dimensional conservation framework combining in situ and ex situ strategies for Acer sutchuenense under climate change.

## Key findings

- Acer sutchuenense's suitable habitat is projected to contract westward due to climate change and dispersal limitations.
- The species' distribution is currently split into two regions, likely due to rugged terrain and limited seed dispersal.
- Key environmental drivers include the Mean Temperature of Driest Quarter and Temperature Seasonality.

## Abstract

Acer sutchuenense is a rare and endangered maple endemic to China, facing severe threats due to habitat loss and rapid climate change. In this study, a MaxEnt model optimized using the kuenm package in R 4.3.1 software was employed to simulate its spatiotemporal distribution. Although the mountains surrounding the Sichuan Basin provided glacial refugia for this species during ancient climate changes, its distribution has now split into two separate regions. This split is likely due to the rugged terrain and the limited natural seed dispersal ability of this species over long distances. Due to the projected migration lag, the natural migration of A. sutchuenense may fail to keep up with the pace of future climate warming. This could lead to the loss of nearly half of its unique genetic resources, especially in its western habitat. Therefore, implementing a framework that combines in situ and ex situ conservation, and establishing ecological corridors, is crucial for the long-term survival and genetic integrity of A. sutchuenense.

Given that Acer sutchuenense Franch., an endangered maple endemic to China, severely threatened by habitat degradation and climate fluctuations, understanding its spatiotemporal dynamics is crucial for formulating conservation strategies. Herein, climatic, topographic and soil variables were employed to simulate historical, present, and future distribution patterns of A. sutchuenense using the optimized MaxEnt model. Our results indicated that Mean Temperature of Driest Quarter (Bio9) and Temperature Seasonality (Bio4) were the key environmental drivers. Since the Last Interglacial, A. sutchuenense had experienced a continuously reduction in its suitable area, though the mountains surrounding the Sichuan Basin functioned as vital glacial shelters. Although the potential suitable habitat was distributed in a ring shape, A. sutchuenense occurs only on the east and west sides of the Sichuan Basin, probably due to the terrain complexity and limited dispersal ability. In the future, A. sutchuenense faces a westward contraction and a migration lag behind climate velocity due to dispersal constraints. Overall, we recommend a multi-dimensional conservation framework that prioritizes in situ conservation in core refugia, urgently establishes ecological corridors to facilitate eastward migration under climate change, implements ex situ conservation through germplasm collection for vulnerable southwestern populations, and enhances long-term monitoring to ensure species persistence.