Evaluating the Effects of Varying Levels and Patterns of Green-Tree Retention: Experimental Design of the DEMO Study
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Keith B. Aubry, USDA Forest Service, Pacific Northwest Research Station, Olympia, Washington 98512 Michael P. Amaranthus, USDA Forest Service, Pacific Northwest Research Station, Grants Pass, Oregon 97526 Charles B. Haipern, College of Forest Resources, University of Washington, Seattle, Washington 98195 James D. White, USDA Forest Service, Pacific Northwest Region, Gifford Pinchot National Forest, Trout Lake, Washington 98650 Brenda L. Woodard, USDA Forest Service, Pacific Northwest Region, Umpqua National Forest, Roseburg, Oregon 97470 Charles E. Peterson, USDA Forest Service, Pacific Northwest Research Station, Portland, Oregon 97208 Cynthia A. Lagoudakisi, USDA Forest Service, Pacific Northwest Region. Umpqua National Forest, Roseburg, Oregon 97470 Alan J. Horton, USDA Forest Service, Pacific Northwest Region, Regional Off~ce,Portland, Oregon 97208 Evaluating the Effects of Varying Levels and Patterns of Green-tree Retention: Experimental Design of the DEMO Study Abstract In western Oregon and Washington, recent changes in federal forest management policy contained in the Northwest Forest Plan have led to new harvest prescriptions on millions of acres of public lands. For example. on upland sites, standards and guidelines now require that live (green) trees are retained in at least 15% of the area within each harvest unit and recommend that at least 70% of this retention is in patches of moderate to larger size (0.2- 1.0 ha or more). These prescriptions [-'or green-tree retention were based on the professional judgement and collective knowledge of many of the biologists who have studied the organisms and ecological processes that characterize these forests, but they have not been rigorously tested nor implemented on a broad geo- graphic scale. Several prescriptions for green-tree retention are being evaluated experimentally by the Demonstration of Ecosys- tem Management Options (DEMO) study. In this paper, we briefly review recent changes in forest management policy and existing information gaps that led to the establishment of the DEMO study. We then provide an overview of the criteria for site selection, the experimental design and harvest prescriptions, the scope of scientific inquiry, and the collaboration that has oc- curred between scientists and land managers. These discussio~isprovide the context and experimental framework for the indi- vidual research papers that comprise the remainder of this volume. Introduction Bureau of Land Management (Tuchmann 1995). In April 1993. in response to this 'timber crisis', In the 1980s, public concern over the fate of the President Clinton commissioned the Forest Eco- northern spotted owl (Strix occidentalis cauri~za) system Management Assessment Team (FEMAT and of the old-growth Douglas-fir (Pseudotsuga 1993, see also articles in Vol. 92(4) of the Jour- i17erzziesii) forests on which it depends (Gutikrrez nal of Forestry) to formulate and assess the con- and Carey 1985, Thomas et al. 1990) led to un- sequences of an array of options for managing precedented local and regional interest in natural federal forest lands within the range of the north- resource management in the Pacific Northwest. ern spotted owl. This assessment was the first This interest, and the political activism it gener- attempt to develop a comprehensive plan for eco- ated, elevated these issues to national prominence system management on a broad geographic scale. (Ervin 1989, Norse 1990). Lawsuits initiated by The resulting management plan came to be known environmental groups resulted in injunctions from as the Northwest Forest Plan (Tuchmann et al. three separate federal district courts and brought 1996). The Record of Decision (ROD) and asso- timber sale programs to a standstill on federal lands ciated standards and guidelines (S & Gs) for the managed by the USDA Forest Service and USDI Plan were published in April 1994 (USDA and USDI 1994a) and lawsuits against the Plan were 'Current address: USDA Forest Service. Alaska ~kgion, resolved in favor of the government in December Tongass National Forest. Juneau, Alaska 99801 1994. 12 Northwest Science, Vol. 73, Special Issue. ! 999 Among the changes in forest management ten structurally and biologically simpler and the policy brought about by the Northwest Forest Plan development of late-successional characteristics is a greater emphasis on maintaining the diver- in these stands may require more intensive silvi- sity of species, structures, and physical and eco- cultural manipulations. Large-scale harvest studies logical processes that are important to the func- in mature, late-successional forests are lacking. tioning of mature, late-successional forest In the Northwest Forest Plan, these forests are ecosystems. These include microclimates asso- defined as single- and multi-storied stands domi- ciated with interior-forest conditions, spatial het- nated by conifers > 53 cm dbh (USDA and USDI erogeneity in forest composition and structure, 1994b; pp. 3&4-26). They comprise 682,300 ha fungi, invertebrates, saprophytic plants, nongame of Matrix lands and Adaptive Management Ar- wildlife, snags, down woody debris, and other eas (USDA and USDJ 1994b; Table 3&4-8) and, structural and compositional features generally thus, are available for timber harvest under the associated with old-growth forests (Franklin et Northwest Forest Plan. Furthermore, old-growth al. 1981). forests are dynamic and it will not be possible to This is not the first time that forest manage- provide cathedral groves of ancient forests for ment objectives have shifted in response to chang- future generations simply by preserving existing ing public perceptions or professional judgements. old-growth stands (DeBell and Curtis 1993). From the 1930s until the mid- to late- 1940s, se- Today's mature forests will become the old-growth lective cutting of the largest and most vigorous forests of the future; thus, if societal objectives trees was widely applied in old-growth Douglas- are to maintain wood production while increas- fir stands in the Pacific Northwest. Long-term ing the extent of forest stands with old-growth studies revealed, however, that subsequent characteristics, we must. begin to develop meth- windthrow mortality was significant and offset ods for managing mature forests for these objec- increases in residual stand volume for at least 25 tives. yr after harvest (Isaac 1956). Clearcu tting replaced In the early 1990s, several private research selective logging in most areas, and from the 1950s institutions and public interest groups in Wash- through the late 1980s, regeneration harvests con- ington and Oregon sought federal funds for re- sisted primarily of clearcuts of various sizes stag- search aimed at addressing these information needs. gered in time and space, followed by slash burn- In response to these lobbying efforts, the Pacific ing and planting. This strategy was designed to Northwest Region of the USDA Forest Service meet legal mandates for multiple-use management received Congressional direction in 1993 to es- on public lands while providing high volumes of tablish a large-scale silvicultural experiment (see timber at relatively low cost, dispersion of cu- Franklin et al. 1999). The Region, in coopera- mulative watershed effects, access for recre- tion with the Pacific Northwest Research Station, ation, and habitat for deer and other game spe- subsequently established the Demonstration of cies associated with early successional forests. Ecosystem Management Options (DEMO) study, Several studies are proposed or underway in a collaborative research effort with the Washing- the Pacific Northwest region to evaluate the ef- ton State Department of Natural Resources, Uni- fects of silvicultural prescriptions designed to versity of Washington, Oregon State University, accelerate the development of late-successional and University of Oregon to evaluate the ecological, forest characteristics in young, managed stands physical, and social effects of retaining live (green) that have regenerated after clearcutting (e.g., trees in harvest units in western Oregon and Wash- Tappeiner 1992, Hanington and Carey 1997, Carey ington. The DEMO study is designed to provide et al. in press). Such experiments are both rel- information to aid in the development of harvest evant and necessary. However, because of sub- strategies that will retain or accelerate the recov- stantial differences in initial conditions-especially ery of some of the species and key ecological fea- the vegetative and structural legacies typical of tures found in mature and old-growth forests. mature forests-responses to retention harvest in In this paper, we briefly review recent changes young, managed forests may be very difYerent from in forest management policy and existing infor- those in mature forests. Mature forests generally mation gaps that led to the establishment of the have a broader array of structures, species, and DEMO study. We then provide an overview of functions, whereas managed plantations are of- the criteria for site selection, the experimental DEMO: A Study of Green-tree Retention 13 design and harvest prescriptions, the scope of logical processes in these forests. However, the scientific inquiry, and the collaboration that has ecological and silvicultural effects of retaining occurred between scientists and land managers. various amounts or configurations of green trees These discussions provide the context and experi- in harvest units have not been quantified (DeBell mental framework for the