Abstract

Modeling species distribution and predicting the effects of climate change on plant species decline are necessary in restoration programs. This study aimed to predict the occurrence and decline of Astragalus verus under climate change in Central Iran with an area of about 123,167 km². We recorded 12 and 71 sites for the dead and alive species using the stratified sampling method, respectively. The general circulation model of CCSM4 was applied at two timeframes of present and 2050 under two climate change scenarios of RCP2.6 and RCP8.5. Four environmental variables of annual mean temperature, the maximum temperature of the warmest month, the precipitation of the coldest quarter, and elevation were selected as the inputs of the nine statistical models. Results indicated that Random Forest model had the best performance in predicting climatic niche and decline of A. verus (AUC and TSS of 0.99) compared to the other models. The suitable habitat and decline for this species are 12.4% and 19.87% of the study area, respectively. With the estimated temperature rise of 3 °C under the CCSM4-RCP2.6 scenario, A. verus habitat will shrink by about 3.4% of the study area and will move toward higher elevations with colder temperatures in the future. Most changes in the suitability of the species will occur in the altitude range of 1800 to 2200 meters because the most temperature and precipitation variations will happen in this elevation stratum. The results can be used to prevent its rapid dieback or even restore vegetation cover in regions with similar conditions.

摘要

在恢复计划中，有必要对物种分布进行建模并预测气候变化对植物物种减少的影响。本研究旨在预测气候变化下伊朗中部面积约123,167 km ²黄芪的发生和衰退。我们使用分层抽样方法分别记录了 12 个和 71 个死亡物种和活物种的地点。CCSM4大气环流模型在RCP2.6和RCP8.5两种气候变化情景下应用于当前和2050年两个时间框架。选择年平均气温、最热月最高气温、最冷季度降水量和海拔4个环境变量作为9个统计模型的输入。结果表明，随机森林模型在预测A. verus的气候生态位和衰退方面表现最好（AUC 和 TSS 为 0.99）与其他模型相比。该物种的适宜栖息地面积和衰退面积分别为研究面积的12.4%和19.87%。CCSM4-RCP2.6情景下预计气温上升3℃，未来A. verus栖息地将缩小研究区域约3.4%，并向海拔更高、气温更低的地区迁移。该物种适宜性的大部分变化将发生在1800至2200米的海拔范围内，因为最大的温度和降水变化将发生在该海拔地层。研究结果可用于防止其快速枯死，甚至可以恢复具有类似条件的地区的植被覆盖。