Treesearch

Communicating the scientific knowledge generated by the Pacific Northwest Research Station is integral to our mission. The 2013 Science Accomplishments reports highlights the breadth of the station’s research, the relevance of our science findings, and the application of these findings. The photographs throughout the report showcase the region where we work and how science is done.

Eastern hemlock (Tsuga canadensis Carriére) and the Carolina hemlock (Tsuga caroliniana Engelmann) are ecologically important tree species in eastern North America forests that are currently threatened by the hemlock woolly adelgid (HWA, Adelges tsugae Annand, Hemiptera: Adelgidae). HWA has spread rapidly from its original introduction site into new areas. Once present, HWA kills its hosts over a period of 4 to 10 years leading to a phenomenon that is known scientifically and colloquially as hemlock decline. To date, quarantine, chemical management, and biocontrol efforts have failed to...

We investigated within-tree population density of a new invasive species in southern California, the goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), with respect to host species and the community of other borers present. We measured emergence hole densities of A. auroguttatus and other borers on the lower stem (bole) of naïve oaks at 18 sites in southern California and on co-evolved oaks at seven sites in southeastern Arizona. We sampled recently dead oaks in an effort to quantify the community of primary and secondary borers associated with mortality—specie...

The Commercial Thinning Research Network (CTRN) was established throughout the spruce-fir forest of Maine beginning in 2000 with substantial funding from the University of Maine's Cooperative Forestry Research Unit. One of six replicates of the precommercially thinned stand condition in the CTRN is located in compartment 23A in the U.S. Department of Agriculture, Forest Service's long-term silviculture experiment on the Penobscot Experimental Forest (PEF), in which the experimental treatments are the timing of the first thinning entry and relative-density reduction. This paper presents...

The Silvicultural Intensity and Species Composition (SIComp) experiment was installed in 2003 on a recently clearcut mixedwood site within the Penobscot Experimental Forest in east-central Maine. This study was initiated because the response of early-successional stands to various intensities of silviculture was poorly understood in the region. The goal of SIComp is to shift stand development and composition in multiple directions through a factorial combination of three silvicultural intensities (low, medium, and high) and three objectives for species composition (hardwood, mixedwood, and...

A compilation of plant lists from all available sources since the 1950s represents the flora of the Penobscot Experimental Forest (PEF), Bradley, Maine. More than 300 taxa of vascular plants in 71 families and 186 genera are included. Approximately 85 percent of the taxa are native to Maine. Ten of 45 nonnative species are considered invasive. Infraspecific taxa have not necessarily been resolved, though 14 subspecies are included as they represent the species in the region. Two rare plants, Carex oronensis and Clematis occidentalis, have been documented. Omitted taxa overlap known species...

Multi-cohort stands maintained by the U.S. Department of Agriculture, Forest Service on the Penobscot Experimental Forest (PEF) have played a central role in research into the mechanisms that regulate ontogenetic trends in forest conifers as they control effects due to population, climatic, and edaphic factors. These long-term silvicultural studies have permitted direct comparisons of trends in morphology and physiology across life-stages, and experimental reciprocal grafting research among juvenile, mid-aged and old-growth individuals has proved an important approach to discriminating...

Depletion of essential mineral nutrients from the rooting zone of trees in northern forests may reduce health and productivity. Long-term field investigations coupled with detailed laboratory studies enhance understanding of the biological processes and suggest means to address potential threats. One such investigation by the U.S. Department of Agriculture, Forest Service, in cooperation with the University of Maine, involves the role of wood-decay. fungi in cycling calcium (Ca) and other essential mineral nutrients. The investigation was established on the Penobscot Experimental Forest...

Robert M. (Bob) Frank, Jr., spent his career with the U.S. Forest Service and oversaw the long-term silvicultural research on the Penobscot Experimental Forest in Maine for nearly 30 years. His reflections here span more than four decades, from his first days with the Forest Service until his retirement in 1996. He touches upon the agency's relations with members of the forest industry and the public, changes in the agency's culture and funding over time, and his role in establishing and sustaining long-term studies that continue to this day.

This bibliography includes all journal articles, technical reports, proceedings, U.S. Forest Service publications, and theses published about or using data from the Penobscot Experimental Forest (PEF) during its first 60 years.