Old-growth research at the H.J. Andrews Experimental Forest

The H. J. Andrews Experimental Forest is located 80 km east ofEugene, Oregon, in the western Cascade Mountains. It has been amajor site for research on old-growth forest and stream ecosystemssince its establishment in 1948. More than half of the 6,400-ha siteremains pristine old growth. The site and research program aremanaged jointly by the USDA Forest Service's Pacific NorthwestResearch Station and Willamette National Forest, and by OregonState University (OSU). Funding comes from these sources and theNational Science Foundation (NSF), National Aeronautics and SpaceAdministration (NASA), the Environmental Protection Agency(EPA), and elsewhere. The Andrews Forest is one of 18 NSF-spon-sored Long-Term Ecological Research (LTER) sites in the UnitedStates where basic research programs on ecosystem structure and processes are underway. Comparative studies associated with theAndrews Forest also exist in Chile, China, Mexico, and Zambia.
Two decades of intensive ecosystem research at the Andrews For-est have taught us much about old-growth forests and associatedstreams. The overall research program addresses: patterns and pro-cesses of forest succession; decomposition of litter, logs, and snags;forest-stream interactions; invertebrate and vertebrate ecology; nu-trient cycling; disturbance regimes of forests and streams; and main-tenance of long-term productivity of forest ecosystems. Researchapproaches include small- and large-scale experimental manipu-lation of the forest and stream ecosystems, long-term field obser-vation of permanent plots and gauged watershed, interpretation ofthe history of vegetation and geomorphic change, and computersimulation modeling of physical and biological processes. Fieldstudies are being conducted on establishment, growth, and mortality of vegetation; nutrient, water, and sediment budgets for small wa-tersheds with old-growth, mature, and plantation forest cover;amounts, movement, and decomposition of large woody debris instreams; decomposition of snags and logs on land; and effects ofnatural and management disturbance patterns on spatial and tem-poral distribution of old-growth forest. Examples of long-term stud-ies include analysis of log decomposition in an experiment designedfor sampling over a 200-year period. The origins and geographicdistribution of old growth have been examined through analysis ofwildfire disturbance history since 1000 A.D.
Field observations and remote sensing of forest stands of differingage, composition, and structure have been used to characterize thestructure and composition of forest ecosystems in a sequence ofstands of varying age up to 800 years. These studies also have sam-pled invertebrates, vertebrates, and soil fungi. An important productof this effort has been the development of definitions of old-growthforest and techniques for their inventory. Modeling studies haveanalyzed the changes in carbon storage and flux of CO, to the at-mosphere associated with converting old growth to managed forests,and the rate of input of large woody debris to streams from adjacentforests.
Long-term data sets produced. by these and other studies are ar-chived in the Forest Science Data Bank at Oregon State Universityand are available for use by cooperating scientists and others. Over1,000 publications and theses, many dealing with old-growth eco-systems, have been produced by the Andrews Ecosystem Program.
Inquiries about old-growth studies at the Andrews Forest can beaddressed to either author.