Projecting Podocarpaceae response to climate change: we are not out of the woods yet

Abstract 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, characterised 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 A. falcatus, P. latifolius, P. elongatus and P. henkelii and both historical climate data (1970 – 2000) and future climate scenarios (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 governed each species’ distribution. Using niche overlap estimates, a similarity test, and indices of niche expansion, stability and unfilling, we explored how niches changed under different climate scenarios. The distribution of the study species was governed by max 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 A. falcatus was predicted to expand to higher elevations under RCP 4.5 and RCP 8.5. Podocarpus henkelii 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 P. elongatus and P. latifolius. Interestingly, P. elongatus, 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 provides insight into potential climate drivers of podocarp persistence and the potential for adaptation of these species. Overall, these results suggest that P. elongatus and P. henkelii may expand to novel environmental niches.