气候变化情景下基于最大熵模型的中国西南地区清香木潜在分布格局模拟

清香木(Pistacia weinmannifolia)是中国西南干旱河谷植被的特征种。本文利用野外调查的165个清香木分布点信息以及22个环境变量数据, 基于最大熵(Maxent)算法构建清香木分布的适宜生境预测模型, 并据此模拟清香木在我国西南地区的适宜分布区, 以及历史和未来不同气候情景下的分布格局变化。结果表明: 清香木生境预测的Maxent模型准确性非常高(AUC = 0.974), 温度季节性变化、极端低温和降水量是限制其分布的主要气候因子。清香木当前的潜在分布区集中在我国西南干旱河谷区, 其适宜生境的气候特征是降水少、温度季节性变化小且无极端低温。对清香木在末次间冰期和末次冰盛期分布的模拟结果表明, 其分布区范围均以诸大江河的河谷为中心, 随气候变化在我国西南地区主要呈现先向东扩张, 然后向西退缩的趋势, 并印证了“冰期走出横断山(glacial out-of-Hengduan Mts.)”的观点。在未来(2061-2080年) 3种典型浓度路径(representative concentration pathway, RCP)的气候情景下, 清香木在我国西南地区的分布都向东扩张, 主要分布在云贵高原与四川盆地结合地带的河谷, 以及云贵高原与广西西部交界地带的河谷中, 这也反映了这些地区河谷地段干旱化的可能, 而当前的潜在分布区趋于消失; 清香木的潜在适宜分布面积在中低浓度路径情景下均将减少约33%, 而在高浓度路径情景下有所增加。

Simulation of the potential range of Pistacia weinmannifolia in Southwest China with climate change based on the maximum-entropy (Maxent) model

Pistacia weinmannifolia is a characteristic species of dry valleys in Southwest China. In this study, 165 presence points of P. weinmannifolia were identified through field surveys, along with point data of 22 environmental factors. The suitable habitat model was formulated using the maximum-entropy (Maxent) algorithm and applied to simulate the potential range of the species in Southwest China, and to project the change of species range in past and future climate scenarios. The results indicate that the Maxent model gave a high accuracy in habitat predictions for P. weinmannifolia. Temperature seasonality, minimum temperature and precipitation were the major constraining climatic factors. Contemporarily, the environment suitable for P. weinmannifolia was located in the dry valleys of major rivers in Southwest China, and the regions was characterized by decreased temperature variability, no temperatures below 0°C, and low precipitation. Simulations using climate scenarios of the Last Inter-Glacial (LIG) and Last Glacial Maximum (LGM) periods indicated that the distribution of P. weinmannifolia was centered around the valleys of major rivers in Southwest China, substantially expanded eastward first, and retreated westward following climate change during glacial and inter-glacial periods, supporting the hypothesis of “glacial out-of-Hengduan Mts.”. Under the future climate scenario (2061-2080) with three representative concentration pathways (RCPs), the potential distribution of P. weinmannifolia was projected to migrate eastward to the valleys in the adjacent region of the Yunnan-Guizhou Plateau and Sichuan Basin, and the adjacent region of the Plateau and western Guangxi, reflecting a high possibility of increasing dryness in the river valleys in the future, while its current distribution might disappear. The potential distribution of P. weinmannifolia would decrease by 33% in Southwest China under the future scenario with both RCP2.6 and 4.5, but would increase with RCP8.5.