Biogeography

• Coupled with millions of years of years of evolution is the phenomenon of continental drift. Landmasses with vast forests drifted from regions of the planet that are tropical to cooler, more temperate parts of the globe. In response, plants have adapted in many ways. Plants adapted to prevailing environmental conditions during a given time period. Dropping leaves for dormancy is one plant adaptation in the deciduous forest biome.
  
  

Symbiosis

• In a deciduous forest, many plants live and interact with other organisms. Some interactions are mutually beneficial. An example is the relationship between gray squirrels and nut trees in North American deciduous forests. Squirrels benefit from the nuts as food, and the trees benefit by having the squirrels distribute their seeds. In other relationships, one party benefits but the other is harmed. Pathogenic fungi that attack trees and shrubs in the deciduous forest biome are an example. The fungi benefit from the nourishment, but harm the tree or shrub. Plants adapt by developing varying degrees resistance to pathogens.
  
  

Human Influence

• Human activity can mimic what occurs in nature. An example is what foresters call coppice regeneration. Many deciduous trees and shrubs produce sprouts from their stumps after they are cut down. The root systems remain intact and a new aboveground plant develops from the existing root system. This adaptation predated human influences but is a common response to human activities. As humans cut down vast areas of forest, new forests sprout up from this regeneration.
  
  

Climate

• Deciduous trees, shrubs and vines are hallmarks of the North American deciduous forest biome. The loss of leaves for the winter is an adaptation allowing these plants to survive harsh winter conditions. As photosynthesis shuts down, leaves that were essential to the plants in the growing season become a liability. They fall off. This is in contrast to trees, shrubs and vines in the tropical rain forest. There, the plants maintain a set of leaves year-round. In the tropical dry forest, tree leaves shed seasonally not from harsh cold but from drought. This is but one example of myriad plant adaptations in deciduous forest biomes.