Edge Effects    Edward Frank
   Sep 27, 2006 17:34 PDT 

There isn't a clear definition of how large an area must be to be old growth. The problem is if you consider it on an ecosystem basis, then smaller patches are affected by so called "edge effects" across their entire stand. There are some intersting articles on the web dealing with edge effects. Here are two examples:

What is Habitat Fragmentation? The Process of Habitat Fragmentation

http://chesapeake.towson.edu/landscape/forestfrag/all_habitatfrag.asp and



You should check them out.

Ed Frank
RE: Edge Effects    James Smith
   Sep 27, 2006 17:53 PDT 

I think ENTS needs to work on some material that is written more in
layman's terms. Sometimes I try to explain habitat fragmentation and the
risks that such fragmentation applies to various systems, and people
respond with a blank stare. And keep in mind that I'm not a scientist,
at all, and have just a bare grasp of the concept myself. It would be
great if we had something that was easy to grasp for the average person.
RE: Edge Effects    Ernie Ostuno
   Sep 28, 2006 14:55 PDT 


Bark Cabin Natural Area comes to mind here...along with most other small
patches of old growth in PA.

This also reminds me of an interesting "edge effect" I noticed while
driving across the back roads of central Pennsylvania and looking at the
ubiquitous large cornfields. Corn stalks at the edge of the field are
often shorter than the stalks just a couple rows in from the edge.
Stalks in the corner of a field were usually smaller than any other
stalks. I always wondered if this was due to wind stress or moisture
stress, as more sunlight reaches the ground at the edge of the field,
allowing the ground to dry out quicker. Trying to solve this mystery
through experiment and observation was one science project I never
attempted, unfortunately.

Another interesting edge effect occurs in the Lake Michigan sand dune
forest. White pines occur in the transition zone from the beech-maple
forest of the interior dunes to the more open cottonwood-spruce of the
foredunes. Their crowns tower above the surrounding trees and are fully
exposed to the strong winds blowing off Lake Michigan. They are
"sculpted" by the winds, by having their downwind limbs grow much longer
and fuller than the limbs growing into the wind.


Re: Edge Effects    Kirk Johnson
   Sep 29, 2006 11:53 PDT 


When I lived in Washington on the Olympic Peninsula about 10 years ago, I
can remember a vivid first-hand demonstration of edge effect. My girlfriend
and I drove up into the Olympic National Forest south of Sequim on a very
windy Easter Sunday (1996 or 1997) to visit a recently clearcut area. This
had been a healthy late-successional stand of mostly Douglas-fir that had
been clearcut as a result of the infamous "Emergency Salvage Timber Sale
Program of 1995," better known simply as the "Salvage Rider" which allowed
clearcutting of healthy green old-growth stands throughout the Pacific
Northwest under the guise of forest health concerns.

Well as we stood there in the middle of the recent clearcut taking photos,
there were large Doug-firs crashing down all along the west edge of the
opening due to the strong winds that day. No way those trees would have
fallen without the large, fresh opening making them vulnerable. It was kind
of scary actually to see so many large trees falling so rapidly before our
eyes. On our walk out we came across a guy cutting through a 4'+ Doug-fir
that had fallen across a logging road, blocking his pickup's only way out. A
friend of ours later joked that we shouldn't have even gone in there that
day because of the weather, and that we were lucky no one had to come and
"salvage" us!

Kirk Johnson