Climate Change Phenology

Warmer temperatures linked to mismatch among forest plants

Photo by R. Last. Did you know that white trilliums fade to pink as they age?

Warmer temperatures are linked to mismatch among forest plants: Many plants are responding to a warming climate by leafing out and flowering earlier in the spring. However, mismatches may occur when species respond at different rates, leading to disruptions in ecological relationships. A new study found that deciduous trees and shrubs are advancing their leaf out timing with warming temperatures faster than native wildflowers are across eastern North America. This mismatch may lead to declines in native wildflowers as they receive less sunlight for photosynthesis in the spring. The results were published in the Journal of Ecology. Many spring-blooming native wildflowers conduct most of their photosynthesis before the canopy trees above them leaf out and shade them over. Lead author Dr. Tara Miller explains, “As temperatures warm, trees and shrubs may block sunlight from reaching the forest floor earlier in the year, leading to a shrinking time period for native wildflowers to photosynthesize with full sunlight.” The study builds on an earlier paper that used flowering and leaf out observations from Henry David Thoreau from the 1850s in Concord, Massachusetts, combined with modern observations, to show that wildflowers are less responsive to climate change than trees. The current study greatly expands the geographical scope of that previous paper. The study highlights the impact that climate change may have by leading to mismatches between different groups of plants. The authors provide suggestions for land managers and wildflower enthusiasts, who may consider steps such as thinning overhead tree and shrub canopy, removing non-native species, and planting rare wildflowers further north to conserve native wildflower populations.

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