A fir wave is a set of alternating bands of

fir Firs are evergreen coniferous trees belonging to the genus ''Abies'' () in the family Pinaceae. There are approximately 48–65 extant species, found on mountains throughout much of North and Central America, Eurasia, and North Africa. The genu ...

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s in sequential stages of development, observed in

forest A forest is an ecosystem characterized by a dense ecological community, community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, ...

s on exposed

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher t ...

slopes in several areas, including northeastern

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. Fir waves develop by wave-regeneration following wind disturbance, and is one of various types of patterned vegetation.

Formation

Fir waves form by the

ecological Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...

process of wave-regeneration. When a tree falls, a gap in the canopy is formed. This exposes trees at the

leeward In geography and seamanship, windward () and leeward () are directions relative to the wind. Windward is ''upwind'' from the point of reference, i.e., towards the direction from which the wind is coming; leeward is ''downwind'' from the point o ...

edge of the gap to greater wind. These trees are thus more likely to die from damage and desiccation than

windward In geography and seamanship, windward () and leeward () are directions relative to the wind. Windward is ''upwind'' from the point of reference, i.e., towards the direction from which the wind is coming; leeward is ''downwind'' from the point ...

trees. These leeward trees eventually die, gradually expanding the gap downwind. At the same time, young trees start to grow in the wind shadow in the windward portion of the gap, protected from the high winds by the surviving trees. The combination of dying trees at the leeward edge and regenerating trees at the windward edge results in the propagation of the fir waves in the direction of the predominant prevailing wind. The period of the waves is variable, typically about 60 years in balsam fir (''Abies balsamea''). One can view these from the Appalachian Trail as it ascends the Hunt Spur of

Mount Katahdin Mount Katahdin ( ) is the highest mountain in the U.S. state of Maine at . Named Katahdin, which means "Great Mountain", by the Penobscot Native Americans, it is within Northeast Piscataquis, Piscataquis County, and is the centerpiece of B ...

Maine Maine ( ) is a U.S. state, state in the New England region of the United States, and the northeasternmost state in the Contiguous United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and ...

. "Looking out to the Owl" and "The Brothers" are extensive areas of this phenomenon.

References

* Wave-Regeneration in High Elevation Subalpine Fir Forests, from Forest and Landscape Ecology course material at Michigan Tech. * Fir waves and life history evolution in the Adirondacks, ecological research by J. Silvertown and M. Dodd. * Fir Waves: Regeneration in New England Conifer Forests, from ''Teaching Issues and Experiments in Ecology''. * Sprugel, D. G. 1976. Dynamic structure of wave-regenerated Abies balsamea forests in the north-eastern United States. Journal of Ecology 64: 889–911. * Shibuya, M., Hagai, N., Sasaji, T., Kikuchi, S., Haruki, M., Noda, M., Takahashi, K., and Matsuda, K. 2004. Stand and self-thinning dynamics in natural Abies stands in northern Hokkaido, Japan. Ecological Research 19:301. {{Reflist Forest ecology Montane ecology

Formation

See also

References