What are Biomes?
Ecologists recognize regions of the Earth that have roughly similar types of vegetation that are adapted to particular environmental conditions. For example, thorny succulent plants such as cacti are associated with desert conditions where water is scarce, while the tall trees and vines of the rainforest are adapted to the warm, wet conditions of the humid tropics. These regions of similar vegetation are called biomes, and their geographic boundaries are largely determined by climate. The seasonal patterns of precipitation and temperaturecreate barriersfor survival and reproduction of the indigenous plants. The plant species living in an area often overcome these barriers in similar ways. Geographic variations in local climates create two distinctbiomes in the Southern Appalachian region:the eastern deciduous biome and the northern coniferous biome.
Most of eastern North America has a temperate climate. Temperate areas are neither too hot nor too cold but experience enough winter to interrupt the growth of perennial plants for a significant portion of the year. Deciduous trees, which lose their leaves during winter, are well-suited to temperate climates. Their leaves can efficiently convert light energy to food but these delicate photosynthetic tissues are vulnerable to freezing. Dropping leaves and shutting down allows deciduous trees to avoid expending energy and resources to maintain these tissues when conditions are unfavorable for photosynthesis. Conifer trees, such as pines, have adopted a different strategy. They produce tough, freeze-resistant needles, which also use less water than deciduous leaves. Although needles are less efficient at photosynthesis than deciduous leaves, conifers can make their own food on winter days when the temperature climbs above freezing.
Encyclopedia ID: p1586
