Effects of climate change and land cover on the distributions of a critical tree family in the Philippines

Abstract

Southeast Asian forests are dominated by the tree family Dipterocarpaceae, whose abundance and diversity are key to maintaining the structure and function of tropical forests. Like most biodiversity, dipterocarps are threatened by deforestation and climate change, so it is crucial to understand the potential impacts of these threats on current and future dipterocarp distributions. We developed species distribution models (SDMs) for 19 species of dipterocarps in the Philippines, which were projected onto current and two 2070 representative concentration pathway (RCP) climate scenarios, RCP 4.5 and 8.5. Current land cover was incorporated as a post-hoc correction to restrict projections onto intact habitats. Land cover correction alone reduced current species distributions by a median 67%, and within protected areas by 37%. After land cover correction, climate change reduced distributions by a median 16% (RCP 4.5) and 27% (RCP 8.5) at the national level, with similar losses in protected areas. There was a detectable upward elevation shift of species distributions, consisting of suitable habitat losses below 300 m and gains above 600 m. Species-rich stable areas of continued habitat suitability (i.e., climate macrorefugia) fell largely outside current delineations of protected areas, indicating a need to improve protected area planning. This study highlights how SDMs can provide projections that can inform protected area planning in the tropics.

Occurrence–habitat mismatching and niche truncation when modelling distributions affected by anthropogenic range contractions

“…Note, niche truncation values here were after species-specific corrections, where a negative value indicates that the truncation was less than the established baseline the impact of human activity on species distributions. This could lead to overly optimistic range estimates that obscure the true threat statuses of species (Pang et al, 2021;Requena-Mullor et al, 2019;Titeux et al, 2016). The biased assessment of species vulnerabilities may then divert conservation efforts and funds away from species that need it (Fuller et al, 2010).…”

“…Consider the occurrence records of a forest‐dependent species sampled from forests in the decades prior to clearance in the year 1980 for urban land‐use (Figure 1). When an SDM using those occurrence data incorporate a land‐use variable from the year 2000, occurrence–habitat mismatching occurs, as occurrences are mismatched with the unsuitable urban land‐use class (Milanesi et al, 2020; Pang et al, 2021; Ryo et al, 2019). Thus, the resultant model may wrongly infer urban land‐use as suitable and underestimate the true impact of deforestation on the species’ range.…”

Modeling the geographic spread and proliferation of invasive alien plants (IAPs) into new ecosystems using multi-source data and multiple predictive models in the Heuningnes catchment, South Africa

“…Nonetheless, the land cover showed to be an important predictor variable for IAP distribution in BRT and RF with climate variables showing dominance in the MaxEnt. Although current land cover was established as a very important variable and also used in similar studies such as Ye et al (2018) and Pang, De Alban, and Webb (2021) for future prediction, the results of the predictions obtained must be used with caution as land cover will likely change in the future.…”

Are Tree Seed Systems for Forest Landscape Restoration Fit for Purpose? An Analysis of Four Asian Countries

“…Seed zone maps have not been defined to guide selection and seed transfer. Recent climate modelling studies indicate that many Dipterocarps and other native tree species will be severely affected by climate change [69][70][71], but such information is not yet applied to inform the selection of species and seed sourcing for restoration.…”