Selecting tree species to restore forest under climate change conditions: Complementing species distribution models with field experimentation

Background:

The ability of plant species to survive and reproduce within specific climatic conditions fundamentally shapes their distribution. Human-induced climate change is drastically altering these conditions at an accelerated rate, primarily through rising global temperatures and shifting rainfall patterns. Drylands, characterized by water scarcity and high temperatures, are particularly vulnerable to the impacts of climate change. The study featured in the sources focuses on two pioneer tree species, Vachellia pennatula and Prosopis laevigata, which Mexico commonly uses for dryland restoration. A recently abandoned agricultural field in Sierra de Álvarez, San Luis Potosí, Mexico, serves as the field study site, representing a typical scenario for dryland restoration efforts in the region. Traditionally, restoration practitioners have selected species based on their current performance and adaptability to existing conditions. However, the changing climate necessitates a shift towards a more forward-looking approach that considers the long-term viability of restored forests.

Goals and Methods:

To assess the suitability of V. pennatula and P. laevigata for climate-adaptive dryland restoration in Mexico, the researchers calibrated Species Distribution Models (SDMs) using presence-only records from the Global Biodiversity Information Facility (GBIF) and bioclimatic data from WorldClim, projecting the models onto twelve future climate change scenarios. To validate the SDM predictions, the researchers conducted field experiments at a degraded dryland site in Sierra de Álvarez, Mexico, where they used open-top chambers and rainout shelters to simulate increased temperature and reduced rainfall, mimicking a moderate radiative forcing scenario for the period 2041–2060. The researchers monitored seedling emergence and establishment rates in both climate-controlled and ambient conditions for both species. They then compared the SDM projections of future habitat suitability with the experimental findings on seedling recruitment to determine if the models accurately reflected the species' responses to climate change in a real-world setting.

Conclusions and Takeaways:

SDMs identified a decline in suitable habitats for V. pennatula. Field experiments actively demonstrated reduced seedling emergence and establishment under simulated future climate conditions, confirming the SDMs' predictions. The study recommends reevaluating the use of V. pennatula in restoration projects and prioritizing its conservation in areas where scientists expect stable climatic suitability. In contrast, SDMs projected stable or increasing habitat suitability for P. laevigata. Consistent recruitment rates observed in both control and climate-manipulated plots validated this prediction. These results indicate that P. laevigata is a more suitable candidate for climate-adaptive dryland restoration due to its resilience to increased aridity. The study calls for scientists to validate SDMs through field experiments to ensure accurate predictions of species' responses to climate change, especially for recruitment success.