Twala Thando C, Fisher Jolene T, Glennon Kelsey L
School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Johannesburg, WITS 2050, South Africa.
AoB Plants. 2023 Jun 8;15(4):plad034. doi: 10.1093/aobpla/plad034. eCollection 2023 Jul.
Under the changing climate, the persistence of Afrotemperate taxa may be threatened as suitable habitat availability decreases. The unique disjunct ranges of podocarps in southern Africa raise questions about the persistence of these species under climate change. Here, we identified likely environmental drivers of these distributions, characterized the current and future (2070) environmental niches, and projected distributions of four podocarp species in South Africa. Species distribution models were conducted using species locality data for , , and and both historical climate data (1970-2000) and future climate scenarios (Representative Concentration Pathway [RCP] 4.5 and 8.5, 2061-2080) to estimate the current and future distributions. We also used this opportunity to identify the most important climatic variables that likely govern each species' distribution. Using niche overlap estimates, a similarity test, and indices of niche expansion, stability and unfilling, we explored how niches change under different climate scenarios. The distribution of the study species was governed by the maximum temperature of the warmest month, temperature annual range, mean temperature of the wettest quarter, and precipitation of the wettest, driest and warmest quarters. The current distribution of was predicted to expand to higher elevations under RCP 4.5 and RCP 8.5. was predicted to lose most of its suitable habitat under RCP 4.5 and expand under RCP 8.5; however, this was the opposite for and . Interestingly, which had the smallest geographic distribution, showed the most vulnerability to climate change in comparison to the other podocarps. Mapping the distribution of podocarps and understanding the differences in their current and future climate niches provide insight into potential climate drivers of podocarp persistence and the potential for adaptation of these species. Overall, these results suggest that and may expand to novel environmental niches.
在气候变化的背景下，随着适宜栖息地的减少，非洲温带类群的存续可能受到威胁。非洲南部罗汉松独特的间断分布范围引发了关于这些物种在气候变化下能否存续的疑问。在此，我们确定了这些分布可能的环境驱动因素，描绘了当前和未来（2070年）的环境生态位，并预测了南非四种罗汉松物种的分布。利用 、 、 和 的物种分布数据以及历史气候数据（1970 - 2000年）和未来气候情景（代表性浓度路径[RCP] 4.5和8.5，2061 - 2080年）进行物种分布模型分析，以估计当前和未来的分布情况。我们还利用这个机会确定了可能控制每个物种分布的最重要气候变量。通过生态位重叠估计、相似性检验以及生态位扩展、稳定性和未填充指数，我们探究了不同气候情景下生态位的变化情况。研究物种的分布受最暖月最高温度、年温度范围、最湿季度平均温度以及最湿、最干和最暖季度降水量的影响。预计在RCP 4.5和RCP 8.5情景下， 的当前分布将向更高海拔扩展。预计在RCP 4.5情景下， 将失去大部分适宜栖息地，而在RCP 8.5情景下会扩张；然而， 和 的情况则相反。有趣的是，地理分布最小的 与其他罗汉松相比，对气候变化表现出最大的脆弱性。绘制罗汉松的分布图并了解它们当前和未来气候生态位的差异，有助于深入了解罗汉松存续的潜在气候驱动因素以及这些物种的适应潜力。总体而言，这些结果表明 和 可能会扩展到新的环境生态位。
