Andrew Larson works in the Watershed Management Division of Seattle Public Utilities as a forest ecology intern. He is also pursuing graduate studies in Forest Ecosystem Analysis at the University of Washington.

Monday, 27 Oct 2003


Just a few weeks ago my life wasn’t quite so busy. I was working full-time in the Forest Ecology Group of the Seattle Public Utilities Watershed Management Division. Now, I’m a full-time student and still working part-time for Seattle Public Utilities.

The City of Seattle owns more than 90,000 contiguous acres in the Cascade Mountains of western Washington. These lands make up the Cedar River Municipal Watershed (CRMW), and supply approximately two-thirds of Seattle’s drinking water. In 2000, the city implemented a habitat conservation plan (HCP) that brought a halt to commercial timber harvest in the CRMW and pledged millions of dollars to habitat restoration efforts.

The HCP focuses primarily on 83 different vertebrate and invertebrate species, of which 14 are identified as species of greatest concern. Conservation strategies vary across the species, but virtually all are associated with late successional or old-growth habitats. Consequently, the Watershed Management Division, and particularly the Forest Ecology Group, are designing and implementing forest restoration treatments in order to accelerate the development of late successional and old-growth forest habitat. There is no shortage of work! When commercial logging stopped within the watershed, approximately 75,000 acres of the 90,000-acre total had been logged at some point in the last century. All of these second-growth forests are candidates for restoration under the HCP; the remaining old-growth forests are not actively managed. Virtually all of the projects I am involved in at the CRMW relate to forest restoration in some way.

Today, however, I’m not at work. I’ve gone back to graduate school at the University of Washington where I study Forest Ecosystem Analysis, and today I have class. Even though I’m not technically working, a good portion of today will be spent on a CRMW-related project. After my forest community ecology class this morning, I’ll spend the rest of the day working on a proposal to conduct research in the watershed.

A huge volume of scientific research has been produced during the last 20 years about the structure and function of old-growth Douglas-fir western hemlock forests, the forests at the center of the old-growth wars that were waged in the Pacific Northwest during the late 1980s and early 1990s. Subsequently, forest ecologists have very good information about how to manipulate young second-growth Douglas-fir forests in the interest of accelerating the development of old-growth structure. However, an astonishingly small amount of published information is available on the structure and dynamics of Pacific silver fir forests — the middle- and upper-elevation forest in the Pacific Northwest.

A significant portion of the second-growth forests in the CRMW are in the silver fir zone. These are also our youngest stands, and because they are situated at relatively high elevations, they grow quite slowly. Thus, there is a great deal of interest in treating these stands, with the goal of moving them toward old-growth structure and function. In part, this translates simply to growing big trees faster and stimulating the development of multiple canopy layers and understory plant communities. We are already quite effective at these aspects of forest restoration. However, some of the finer details of old-growth silver fir forests are not known — for example, the dominant spatial patterns (i.e., how the trees are arranged in space). The research proposal I’m working on today outlines a project to characterize the spatial patterns and population age structures present in old-growth silver fir forests. This research will hopefully provide a reference against which we can calibrate our restoration prescriptions for silver fir stands. The research will have to wait for now, however. I’m late for class!