Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension agent for Benton, Linn and Polk counties.

Forests disturbed by fire or harvest look different than they did before the disturbance.  Just how different depends on the size and intensity of the disturbance, of course.  It’s no surprise that a site changed by fire or harvest clearly loses its value to certain wildlife species who like dark, closed forests.  But, disturbance creates opportunities for many other species of plants and animals which prosper in the different, more open environment as the forest rebounds. 

Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension agent for Benton, Linn and Polk counties.

People enjoy and cherish Oregon’s forests for a number of reasons.  High among them are the beauty and the variety of plants and animals that live there.

While most of us picture older forests when we read that, we would be wrong to think of that as the complete picture.  Nonetheless a large part of our emotional, scientific and social energy is directed towards those older forests.

Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent, Benton, Linn and Polk Counties. 

We have written about forest diversity, its importance in providing habitat for different species, or a species at different seasons or at different stages of its development.  We have addressed the forest, trees and shrubs in particular, but the importance of habitat diversity applies to other parts of the forest environment too.  Like streams.

We learned about the importance of having different stream habitats to support fish, insects and other aquatic life while on a recent Extension tour.    A stream can have many types of habitat.  The anatomy of a stream (the stream’s morphology) can be described in terms that are familiar to anglers: pools, riffles, glides, bars and tail outs.  Each term describes a different combination of water depth and flow that together provide a type of habitat.  You can see and often hear this:  Some parts are quiet (pool and glide), some gurgle their presence to those nearby (a riffle), while falls and a plunge pools announce themselves at a distance.  Aquatic biologists get excited about streams with a good mix of these habitats in a stream reach, just as wildlife biologists get excited by forest structure and snags.  Hmm.  Continue reading →

Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent, Benton, Linn and Polk Counties. 

I was recently on a tour where we looked at how growing conditions, productivity and plant communities all change across the landscape according to elevation, soils, rainfall, aspect and other factors.  These are often included in the term “site productivity”.  These factors give important insights to the ability of a site to support different types of plants, and also how well they will grow there.  This capacity to produce biomass, or support tree growth is often expressed in the important forestry concept of site class as described in this article.

We traveled from near the crest of the Coast Range back to the Valley floor to watch changes in site class and vegetation.  Our final stop was a rock sitting on a small hill beside a vineyard in Yamhill County, looking out across the Willamette Valley.

It is a large rock (about 90 tons), unrelated to any of the bedrock of the hill.  This rock helps tell a story of events during the last ice age that shaped the Willamette valley and its historic vegetation.  It influences the present, largely agricultural, vegetation as well. Continue reading →