Climate Change and the Future of Natural Disturbances in the Central Hardwood Region

Abstract

Spatial patterns and ecological processes of the USA central hardwood forests reflect past climatic conditions and natural disturbance regimes. Changes in climate can lead to disturbances that exceed their natural range of variation, and the impacts of these changes depend on the vulnerability or resiliency of these ecosystems. Global Circulation Models generally project annual increases in temperature across the Central Hardwood Region over the coming decades, but changes in precipitation are less consistent. More unclear is how climate change affects severity and frequency of natural disturbances, such as severe storms, fires, droughts, floods, and insect outbreaks. We use a time-series satellite data record to map the spatial pattern and severity of broad classes of natural disturbances the southeast region. Between 5 % and 25 % of forest land was affected by disturbance each year since 1985 across the four regions. The time series reveals periodic droughts that are widespread and low-severity but associated with more localized, high-severity disturbances such as fire and insect outbreaks. The map also reveals extensive anthropogenic disturbance across the region in the form of forest conversion related to resource extraction and urban and residential development. Changes in climate and disturbance regimes might affect these forests in the future via altering the exposure, sensitivity, and adaptive capacity of these ecosystems. Changes in climate are highly likely to expose forests to more frequent and severe disturbances, but ultimately how vulnerable or resilient forests are to these changes depends on their sensitivity and capacity to adapt to novel conditions.