Potential spatiotemporal distribution changes and conservation recommendations of two connected endangered tree peony species (Paeonia decomposita & P. rotundiloba)

Abstract

• Temperature seasonality and UVB seasonality were the most critical factors shaping the distribution of Paeonia decomposita and P. rotundiloba . • The historical period distributions of the two speices were in the southwest of the current distribution. • The potential distribution of the two tree peonies continued to expand and migrated to high-altitude areas in the north in future. • Establishing priority reserves in advance according to the model prediction is an effective protective measure. Genus Paeonia L. has important economic values in ornamental, medicine and food. China is one of the distribution centers of Paeonia and the origin to all wild species of section Moutan . Nowadays, most tree peonies species are in danger of extinction, but their geographical distribution is still unclear, hindering further resource protection. In this work, based on comprehensive environmental data and long-term presence records, the maximum entropy (MaxEnt) model was used to predict the past, current and future potential distribution of two Chinese endemic and endangered species, Paeonia decomposita and Paeonia rotundiloba. The results showed that the two species were narrowly distributed in Western Sichuan (Aba and Ganzi), China, with the temperature seasonality and UV-B seasonality being the most important environmental variables to determine the habitat suitability of the both tree peonies. In addition, growing degree days and precipitation seasonality also had an important impact on P. decomposita and P. rotundiloba, respectively. The reconstitution for the past distribution showed that they were mainly distributed in the south foot of Hengduan Mountains in the last interglacial (LIG) period. The reconstitution for historical suitable distribution indicated that the two tree peonies would migrated along Hengduan Mountains and Yarlung Zangbo River into the southeast of Qinghai Tibet Plateau, northeast from the current distribution. The areas of current potential distribution of the two tree peonies, which were partially crossed, were 14050 km 2 and 45299 km 2 respectively. Under different future climate scenarios, the potential distribution of the two peonies continued to expand and migrated to high-altitude areas in the north if the greenhouse gas concentration will continue to increase. This study will not only provide theoretical guidance for the conservation of P. decomposita and P. rotundiloba , but also help to understand the evolution and migration process of section Moutan.