Changes in ecosystem structure and function are being influenced by changes in seasonal patterns of temperature and precipitation, consistent with predicted anthropogenic climate change. Management of protected areas in the Anthropocene requires information not just on changes in seasonal average temperatures (shown to be extreme at many US national parks), but also in patterns of seasonal warming (e.g., accumulated heat) which influence the timing of key phenological events in many species. Management of park resources will be enhanced by information that helps managers forecast and respond to changes in the timing of activities such as treating invasive species, operating visitor facilities, and scheduling climate-related events (e.g., flower festivals, fall leaf-viewing). Seasonal changes in vegetation, such as pollen, seed, and fruit production are important drivers of key ecological processes in parks. Here, using estimates of start of spring based on climatically-modeled dates of first leaf and first bloom derived from indicator plant species, we evaluate the recent timing of spring onset (past 10-30 years) in each US natural resource park relative to its historical range of variability across the past 112 years (1901-2012).
Of the 276 parks examined, spring is advancing in approximately three-quarters of parks (76%), and 53% of parks are presently experiencing an “extreme” early spring exceeding 95% of historical conditions. Our results demonstrate how changes in climate seasonality are important for understanding ecological responses to climate change, and further how spatial variability in climate change effects necessitate different approaches to management. We conclude with discussion of how our results inform climate change adaptation challenges and opportunities facing parks, with implications for other protected areas, by exploring consequences for resource management and planning, as well as the need for monitoring and communication of findings to key audiences.