The phenology of fall foliage coloration in temperate forests is an important bioindicator of plant response to environmental changes and is associated with various ecosystem processes and animal activities. The process is also an important element in fall foliage ecotourism. However, it is not well understood how the timing of fall foliage coloration responds to environmental changes over time and space, which limits our ability to predict impacts from climate change and extreme weather events. This study focuses on onset and end dates of peak coloration in deciduous forest fall foliage determined from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery in eastern United States from 2000 to 2018. Statistical model selection was used to identify important environmental factors that affect spatial and temporal variations of peak coloration dates among thirty ecoregions in central and eastern United States.
Results/Conclusions
Results suggest temperature in spring, summer and autumn, and environmental stresses from heat, drought, heavy rainfall events in summer and autumn play important roles in affecting the inter-annual changes of fall foliage peak coloration dates. Warmer springs were associated to earlier peak coloration dates by 0.7 – 0.9 days/degree on average, while warmer autumns were associated with later peak coloration by 0.6 – 1.1 days/degree on average. In contrast, fall foliage peak coloration phenology among ecoregions showed divergent responses to extreme weather events in summer and autumn (-2.3 – 2.6 days/event). The diverse responses had interesting spatial patterns which may related to local environmental conditions. The effects from those climate variations had different magnitudes on the timing of foliage peak coloration in forest communities among ecoregions. This study reveals important spatiotemporal fall phenological responses to environmental changes and the diverse responses among ecoregions in temperate deciduous forests ecosystems. The findings imply significant yet divergent impacts from climate change and extreme weather events on forest ecosystem processes in autumn with topographic effects from landscape.