[at-l] Fir waves

[The Weathercarrot]

As an aside to the treeline thread, below is an  interesting description of 
fir waves. The most extensive example I've seen of fir waves is on the 
plateau adjacent (west) of Katahdin, easily seen from the Hunt Spur. A photo 
of it can be seen near the end of part one of my AT DVD, as well as the 
original jpeg on the DVD-ROM portion.

========================================

from http://www.connix.com/~harry/treeline.htm :

In areas of extremely high winds, the multiplicity of mechanical factors may 
combine to effect synchronized patterns of mortality known as fir waves, 
found in the northern Appalachian Mountains and in northern Japan (Reiners 
and Lang 1979). The dieback zones lie approximately 100m apart, and are 
characterized by a continuum that ranges from taller, windward trees to a 
death and regeneration zone to leeward (Marchand, Goulet, and Harrington 
1986). The taller trees perish due to exposure to full wind and weather 
effects, eliminating the shelter for the adjacent lower profile canopy and 
thus allowing the wave to progress; regeneration occurs in the wake of the 
wave due to the release of seedlings favored when the overstory is removed 
(Sato and Iwasa 1993). Maloney (1986) studied fir waves in the Adirondack 
Mountains (New York, U.S.A.) and suggested that fir waves represent an 
orderly spatial reorganization under directional environmental stress for 
two primary reasons: first, the transit of a fir wave through a forest 
restructures the community in terms of providing suitable conditions for the 
development of understory species such as vascular herbs and bryophytes; and 
second, the wave phenomenon naturally produces even-aged stands with similar 
growth profiles that present the uniform obstruction to wind that is 
necessary for the wave to perpetuate.