The Problem with Mountains
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Every use of the biome concept eventually runs into the problem of mountains. Mountains and mountain ranges represent islands of often different types of vegetation than the surrounding region. In the Eastern Deciduous Forest exist such ranges as the Appalachians (including the Great Smokey Mountains), the Adirondacks in New York, and the White Mountains of New Hampshire. Mountains rise above the average elevation of the Eastern Deciduous Forest. As elevation increases, the average temperature decreases. Weather systems normally move from west to east and as these air masses reach the Appalachian Mountains, as an example, the rising air becomes cooler. Cooler air can hold less water vapor than warmer air and condenses as clouds or in the form of rain. Therefore as the elevation increases on a mountain not only does it become cooler, but normally precipitation increases as well. Tree and other plant species are adapted to particular environments. Therefore under the cooler, wetter conditions near the tops of the mountains, species adapted to these conditions prevail, usually conifers. In fact the conifer forests of the mountains of the Eastern Deciduous Forest are little different from the conifer forests of the Northern Boreal Forest (Taiga). If the mountain is tall enough even the conifers disappear and are replaced with shrubs, grasses, and plants with a great resemblance to tundra vegetation. These changes in plant species recapitulating the greater biome ecosystems are sometimes called life zones. One of the classic examples of the mountain effect is Mount Washington in New Hampshire. Mount Washington is the highest mountain (6288 feet) in eastern North America and is part of the White Mountains. Summer high temperatures near the summit are about 50 degrees F. Low temperatures in the winter regularly reach below -40 degrees F. The wind is ferocious at the top and with wind chill the winter weather on the summit of Mt. Washington is considered among the worst in the world. The base of the mountains is surrounded by a transitional Eastern Deciduous Forest with beech, maples, hemlocks, and pine. A road runs up the mountain. As you go up the mountain the deciduous trees are replaced with spruces and firs of the same species found in the Northern Boreal Forest. If one continues to go up the conifers become stunted (1 to 2 feet in height) and windswept and contorted because of the high winds. Near the summit the conifers disappear and are replaced by grasses, herbaceous plants, and bare rock, an ecosystem typical of the rocky parts of the arctic tundra. The summit of Mt. Washington is famous for a relict population of the butterfly Oeneis melissa. This species of butterfly does not occur anywhere else except in the arctic tundra of North America and the alpine zone of the Rocky Mountains.

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