THESE NOTES HAVE NOT BEEN UPDATED FOR SEVERAL YEARS. WHILE CONCEPTS ARE PROBABLY STILL VALID, SOME INFORMATIONHAS UNDOUBTEDLY CHANGED SINCE THE LAST UPDATING!! We've explored some of the historical pattern of logging in forests of the Pacific Northwest (PNW), the characteristic features of old-growth forests in this region, and the roles of those features in the forests. We've also looked at the circumstances (political and ecological) that are driving changes in these practices, at least on Federal lands in the region. The following notes discuss the conventional methods used in logging and subsequent site preparation in the region, their consequences for the ecosystems, changes that are taking place in those methods (at least on Federal lands), and the likely benefits that will result from those changes.
If you want to jump directly to any of those topics, just make your selection from the following list:
Conventional clear cutting and site preparation
techniques(directly below, rather than a link)
Consequences of those techniques
New methods that focus on "ecosystem management" and likely benefits that will result from the changed methods
We'll focus on clearcutting (removing all standing trees), because it has been the most widely practiced technique in our region, and because it often represents the extreme in the spectrum of possible disruptions associated with logging (for example, versus selection cuts in which only some trees are removed).
There are various degrees of clearcutting, but we'll focus on the most common type - stem-only harvesting, in which only the tree boles (trunks) are removed, and stumps, roots and branches are left in place or disposed of on site. More intensive utilization types of cutting also remove all branches and even stumps and roots.
Clearcutting has typically been used in part because it is the simplest technique, from the perspective of the logging operation. It is generally much easier to cut everything than to selectively remove a few trees. It has also been used because the preferred timber species in our region, Douglas-fir, is considered to be relatively intolerant of shade, achieving fastest growth rates in full sun.
Clear cutting is often followed by various forms of site preparation -- getting the site ready to be planted or naturally regenerated from seed available on or near the site. As we'll see, the site preparation methods used have important consequences for the ecosystem - it isn't just the cutting of the trees that is important! Site preparation methods, again, have been selected based on both operational considerations (what is easiest to do and will make it easiest to work on the site later) and on the regeneration characteristics of the species that will be planted or naturally regenerated. Again, Douglas-fir has been the preferred species for a long time, and so its requirements (or optimum conditions) have influenced the site preparation techniques used. It establishes and grows best on bare mineral soil rather than on deep organic duff.
Site preparation west of the Cascades has most commonly involved burning of "slash" - branches and cull ("reject") wood that are left after the logs are removed.
Why burn slash? This has been done for several reasons:
Slash burning can be done (basically) in one of two ways:
By piling it with equipment like a bulldozer and then burning the piles, or by burning it as it lays ("broadcast burning").
Piling and burning is generally less expensive and risky -- not as many people are needed to monitor the fire, and there is less chance of the fire getting away -- but it is usually more destructive. Often, the scraping and piling removes (and piles) not only the slash, but also the duff and even, in some cases, a good bit of the top soil (with its organic matter and nutrients). This is called "scarification" of the site. Scarification is often most intensive when foresters are relying on natural (seed) regeneration than when they are going to plant seedlings, because, again, some species germinate and establish best on bare mineral soil.
Click PNW consequences to explore some of the consequences of these traditional methods for the site's nutrient and water status, or PNW changes to look at recent changes taking place in forest management in the PNW and their likely consequences. Click the Contents box at the bottom is you want to return to the master Table of Contents for this BI 301 web site, or "navigate" for reminders on how to move about within and among these pages.
Page maintained by Patricia S. Muir. Last updated November 24, 2002.