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Chapter 03: Plant Life of the Central Appalachians
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CHAPTER 03 [3.89.200.155] Project MUSE (2024-03-29 08:03 GMT) PLANT LIFE OF THE CENTRAL APPALACHIANS THE VEGETATION OF THE CENTRAL APPALACHIANS as we know it today is the result of a number of factors that have been in play for a very long time. The region has a diverse assemblage of plant species (the flora), and the member species in this assemblage are found in different combinations across the landscape. A few species have a restricted distribution and are found only in certain limited habitats (e.g., trees such as red spruce that are confined to the very highest elevations, which are cool and moist throughout the summer months), while others are exceedingly common and seem to be just about everywhere (e.g., red maple and many of the more common roadside weeds). Most species fall between these two extremes. Since each species is associated with a particular type of environment, it follows that those species with similar requirements often appear together, forming a plant community. Just how long a species has been present at a particular place, how it might have reached the place, where it came from, what factors limit where it can survive, and what the species contributes to the biotic communities of which it is part are all things that need to be considered if one is to develop a more complete understanding of vegetation in the Central Appalachians, or indeed anywhere on earth. At the onset of the Cenozoic era some 65 million years ago, the continents of North America, Europe, and Asia were much closer to each other than they are today. Land connections existed between North America and Europe in the east as well as North America and Asia in the west, so that the three continents formed a near-continuous land mass across the greater part of the northern hemisphere. Moreover, earth’s climate was milder than at present, with small differences in temperature between winter and summer and at high and low latitudes. Thus there were few geographical, ecological, or climatic barriers to prevent the spread of plants (and also animals) from one place to another. This situation persisted until near the middle of the Cenozoic and resulted in a uniform flora throughout the northern hemisphere. This flora has been referred to as the Arcto-Tertiary Geoflora. During the second half of the Cenozoic the earth’s climate began to cool, the continents became more widely separated, and barriers to dispersal appeared. The most important of these in North America was the drying that occurred in the center of the continent as a consequence of the uplift of the Rocky Mountains. This created a major ecological barrier that essentially isolated eastern North America from western North America. Other, similar barriers appeared in Europe and Asia. As a result, the once continuous Arcto-Tertiary Geoflora became disrupted, and the floras of individual regions of the northern hemisphere became increasingly distinct. Yet even today there is a high degree of similarity at the taxonomic level of genus, and anyone from the Central Appalachians who visits northern Europe or eastern Asia quickly realizes that the forests in all three places contain easily recognizable examples of many of the same genera of trees. This is also true of certain remote parts of Asia. In 1987 I spent three months as a Fulbright scholar at Himachal Pradesh University in northwestern India, which is almost half a world away from the Central Appalachians. Nevertheless, the forests in that region of India contained appreciable amounts of oak at intermediate elevations, with forest composition changing to spruce and fir at higher elevations. This pattern of forest vegetation is similar to what one finds on some of the higher mountains in Virginia or West Virginia, although fir (either balsam fir or Fraser fir) is limited to just a few localities. Other trees common to northwestern India and the Central Appalachians include pine, birch, buckeye, and musclewood, although the species are different in the two regions. The current distributions of oak, spruce, and fir in both northwestern India and the Central Appalachians reflect a pattern that became increasingly apparent during the second half of the Cenozoic as the two major taxonomic groups of trees, gymnosperms and angiosperms, gradually evolved to occupy different ecological habitats. Gymnosperms became concentrated in areas at high latitudes and high elevations, with angiosperms more FIGURE 19 Beechdominated forest in the Dalaoling Preserve of China 49 03 PLANT LIFE OF THE CENTRAL APPALACHIANS...