The dense ceiling of tree crowns has a strong buffering effect on the microclimate of the forest floor, which delays the undergrowth response to climate warming. Unfortunately, the progressive warming is also increasing the frequency and intensity of extreme weather events and attacks by insects and fungi that damage and kill trees, which leads to the forest canopy opening and reduces its buffering properties. As a result of these processes, changes in the microclimate of the forest floor rapidly accelerate, which threatens the preservation of the biodiversity of the undergrowth, because the species that build them live in conditions that are more and more deviating from the optimal.
Original work: https://science.sciencemag.org/content/368/6492/772