Planning priority conservation areas for biodiversity under climate change in topographically complex areas: A case study in Sichuan province, China

conservation. Therefore, climate change would lead to shifts in sensitive species distributions, while planning new conservation areas was a necessity for biodiversity conservation in the study area. 3.2. The effect of topography on adaptation to climate change Fig 5A showed the temporal distribution of topographic position index (TPI). In detail, the area of steep slope comprised the least area and was concentrated in the western part of Sich- uan province. Spatially, the areas of side slope were more widely distributed than others. According to TPI, a result from the sliding window algorithm quantitatively assessed an index of topographic diversity, as shown in Fig 5B. Spatially, high diversity areas were mainly located around a transitional zone between the plain and the plateau where the topographic position included 11 types. Additionally, climate change trends in different periods are shown in Fig 5C and 5D, which shows changes in the coldest monthly temperature in the future. Compared with the period of 1981–2010, the projected climate change shows an obvious increase in Sichuan Province and the increasing range is between 0.2˚C- 1.9˚C in the future. As for regional comparison, the rise of temperature in the western Sichuan Plateau is higher than that in the Sichuan Basin, indicat- ing that the impact of climate change on biodiversity may be profound in these areas. Our method was applied to assess the effect of topographic complexity on adaptation to cli- mate change (Fig 5E and 5F), which displayed the spatiotemporal distribution of adaptation

for the periods of 2011–2040 and 2031–2060, respectively. The effect decreased with the vari- ability of elevation and from west to east. The highest values of adaptation index near 100% when the coldest monthly temperature increased below 0.3˚C. On the contrary, the effect strongly decreased with the temperature reaching values of 1.2˚C. Meanwhile, the results revealed that the relationships among topographic complexity, temper- ature change, and adaptation could be represented by a nonlinear function (Fig 5G). A significant difference could be observed in the topography effect of different temperature ranges (Wilcoxon signed-rank test, P < 0.05). It also showed that adaptation would decrease to 60% when the cold- est monthly temperature rises more than 1.2˚C in most regions. Thus, a quantitative evaluation could comprehensively understand the effect of topography on conservation planning. 3.3. The distributions of priority conservation areas The distributions of priority conservation areas for two time periods were optimized by the Marxan model, as shown in Fig 6A and 6B. The area of priority conservation areas covered Fig 4. The changes of the number of species in the future (a represents the period of 1981–2010, b represents the period of 2011– 2040, c represents the period of 2031–2060). https://doi.org/10.1371/journal.pone.0243425.g004 PLOS ONE Planning priority conservation areas for biodiversity under climate change in topographically complex areas PLOS ONE | https://doi.org/10.1371/journal.pone.0243425 December 23, 2020 8 / 15