COS 32-5
MOVED TO WED COS 74-10 4:40 309/310 Fall phenological response patterns in deciduous forest communities of northeastern North America
Observed phenological changes in recent decades across temperate forest regions, such as earlier leafing in the spring or later leaf senescence in the fall, provide a dramatic indication of biological response to climate change. While mechanisms of spring phenology (bud burst, leafing out, and flowering) have been well studied and integrated into predictive models of future responses to climate change, it is still unclear how fall phenology in plants (leaf senescence and dormancy) responds to environmental variation. Although delayed leaf coloration and abscission in deciduous forest trees have been observed in Europe and North America in recent decades, the role of different environmental triggers and how they interact in different species to produce observed fall phenological patterns remains unknown. There is a long list of environmental changes or stressors during growing season that may affect phenological change in fall. Based on remotely sensed phenology data, we detected multiple significant effects of temperature, precipitation, and other weather stressors on the timing of dormancy of deciduous forests communities in New England from 2001 to 2010 using a Bayesian Model Averaging regression method.
Results/Conclusions
The timing of deciduous forest dormancy responds not only to decreasing temperature in fall, but also to precipitation, drought, frost, heat and other extreme weather events during the growing season. Among those factors, cold degree days had the highest contribution to dormancy date variation. Earlier dormancy dates were related to negative effects of environmental stresses (cold, frost, heat and drought), and non-linear effects of summer and fall precipitation were found. Deciduous forests in the northeastern highlands, which are dominated by maples and birches, have higher sensitivity to weather condition changes than forests in coastal areas that are dominated by oaks. Deciduous forests in these two eco-regions also showed different responses to summer drought and precipitation in summer and fall. Additionally, summer precipitation interacted with heat affecting dormancy dates of forests in coastal area. The results suggest a complex mechanism of spatiotemporal fall phenology responses and different triggers and effects for different forest communities. Our study improves the understanding of fall phenological responses to variation in weather patterns in temperate forest communities and provides a way to build predictive models of future responses to climate change.