Climate change is advancing spring onset across the U.S. national park system

Abstract

Abstract. Many U.S. national parks are already at the extreme warm end of their historical temperature distributions. With rapidly warming conditions, park resource management will be enhanced by information on seasonality of climate that supports adjustments in the timing of activities such as treating invasive species, operating visitor facilities, and scheduling climate-related events (e.g., flower festivals and fall leaf-viewing). Seasonal changes in vegetation, such as pollen, seed, and fruit production, are important drivers of ecological processes in parks, and phenology has thus been identified as a key indicator for park monitoring. Phenology is also one of the most proximate biological responses to climate change. Here, we use estimates of start of spring based on climatically modeled dates of first leaf and first bloom derived from indicator plant species to evaluate the recent timing of spring onset (past 10-30 yr) in each U.S. natural resource park relative to its historical range of variability across the past 112 yr . Of the 276 high latitude to subtropical parks examined, spring is advancing in approximately three-quarters of parks (76%), and 53% of parks are experiencing "extreme" early springs that exceed 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 effects of climate change necessitates different approaches to management. We discuss 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.

Ecological monitoring and evidence‐based decision‐making in America's National Parks: highlights of the Special Feature

“…A new paradigm for protected-area conservation has emerged that recognizes the highly dynamic and vulnerable nature of park ecosystems and emphasizes active interventions (e.g., restoration; Hobbs et al 2010). Monahan et al (2016) show us that the onset of spring is advancing in most parks, as Monahan and Fisichelli (2014) have demonstrated previously that the entire NPS system is actively experiencing temperature increases. This is particularly evident in the papers about global change impacts on parks.…”

Studying plant–pollinator interactions in a changing climate: A review of approaches

“…Using statistical and modeling approaches, researchers have been able to assess the impact of changing temperature on flowering onset, as well as address other questions using these data sets (Appendix S1: Table B). To develop a statistical approach to assess the relative phenology changes in 276 U.S. National Parks and Preserves across the contiguous United States and Alaska, Monahan et al (2016) used species-specific spring indices for three nonnative indicator species (a cloned lilac cultivar and two honeysuckle species commonly found in these locations). Spring indices included first leaf and first bloom indices, which are based on the number of accumulated growing degree-days.…”

Defining frigid winter illuminates its loss across seasonally snow-covered areas of eastern North America

“…Other studies have likewise reported that earlier springs drove trends in reduced winter duration (Dye 2002, Allen and Sheridan 2016, Kutta and Hubbart 2016. In addition, proxies for the beginning of spring, particularly phenological data describing budbreak, leaf emergence, and leaf out, have been widely used to document earlier springs (Richardson et al 2006, Schwartz et al 2013, Piao et al 2015, providing further evidence for an advancement of spring onset by −0.8 to −0.9 d per decade in the northeastern US from 1901 to 2012 (Monahan et al 2016). Our findings of later onset of winter, earlier onset of spring, and the overall shortening of the winter period resonate with the results of previous investigations of shifting vegetation phenology.…”