PS 3-42 - Assessing forest passive recovery after widespread climate-induced tree mortality

Abstract: Recent extreme climatic events are inducing severe disturbance in forest ecosystems, boosting tree mortality beyond background levels, and altering forest successional pathways and ecosystem services, especially in secondary forests regenerating after human disturbance. However, our understanding of the patterns and drivers of forest recovery after climate-induced tree mortality is still very limited, restricting our capacity to actively aid ecosystem restoration. The aim of this study is to analyze forest ecosystem recovery following the widespread climate-induced tree mortality induced by the February 2011 frost in secondary and mature stands of the northmost neotropical dry forest in northwestern Mexico. In 2021, we established 24 permanent plots, 3 per site, representing a continuum of passive ecosystem restoration from early successional to old-growth forests. In these 24 plots, we annually survey vegetation, soil properties, and canopy openness using hemispherical photography, while HOBO sensors measure daily temperature and light. Our biotic and abiotic indicators of recovery are canopy greenness and openness, tree richness, plant density and biomass, soil N and P, soil organic matter, air temperature, and light. We found that the annual minimum temperature is higher in old-growth forests. In contrast, maximum temperature and light levels are greater in early successional stands in agreement with their lower canopy cover, greenness, tree richness, and biomass. We conclude that old-growth forests buffer against extreme temperatures and modulate climate-induced tree mortality. Conversely, regenerating forests, which endure more extreme temperatures and solar radiation, are likely more vulnerable to further climate-induced disturbances, which may slow or disrupt their recovery.