Distinct ecological habits and habitat responses to future climate change in three east and southeast Asian Sapindus species

Sapindus is an important biodiesel, biomedical, and multifunctional economic forest species in Asia; however, its germplasms have been persistently damaged or lost. Thus, it is imperative to conserve the diversity of Sapindus. This study aimed to reveal the potential habitat distribution patterns of Sapindus mukorossi, Sapindus delavayi, and Sapindus rarak in response to the current environment and future climate change. Furthermore, we aimed to identify hotspots of habitat degradation/expansion to facilitate climate change-adaptive biological conservation. Using current environmental data and future climate projections (2021–2100), we simulated the present and potential future habitats of Sapindus mukorossi, Sapindus delavayi, and Sapindus rarak using a maximum entropy (MaxEnt) model that was developed based on 2041 occurrence records. The model showed that precipitation may play an important role in framing the potential habitats of Sapindus. Notably, S. delavayi was more sensitive to minimum temperatures (−4 °C to 5.5 °C), soil moisture (82–132 mm), and elevation (1200–3200 m), whereas S. rarak was the most sensitive to isothermality (50–86) and soil moisture (54–126). Under the current environment, Sapindus mukorossi had the widest suitable habitat distribution (252.50 × 104 km2), followed by that of Sapindus rarak (215.62 × 104 km2) and Sapindus delavayi (90.86 × 104 km2). Under future climate change scenarios, the habitat distribution of Sapindus mukorossi was predicted to expand at higher latitudes and extensively contract at lower latitudes. Moreover, the projected suitable habitat distribution of S. delavayi showed inconspicuous expansion and contraction, whereas that S. rarak underwent conspicuous contraction and expansion. Moreover, there were distinct ecological habits among Sapindus mukorossi, Sapindus delavayi, and Sapindus rarak in the east and southeast Asia. Thus, it is recommended that the contraction areas should be preferentially subjected to germplasm collection and conservation. Based on these findings, we propose preserved areas as the base for future Sapindus mukorossi, Sapindus delavayi, and Sapindus rarak conservation, breeding, cultivation, and utilisation.