Treesearch

Animals may partially overcome environmental constraints on fitness by behaviorally adjusting their exposure to costs and supplies of energy. Few studies, however, have linked spatiotemporal variation in the energy landscape to behaviorally mediated measures of performance that ostensibly influence individual fitness. We hypothesized that strength of selection by North American elk (Cervus elaphus) for areas that reduced costs of thermoregulation and activity, and increased access to highquality forage, would influence four energetically mediated traits related to fitness: birth mass of...

The marbled murrelet (Brachyramphus marmoratus) is a declining seabird that is wellknown for nesting in coastal old-growth forests in the Pacific Northwest. Most studies of habitat selection have focused on modeling terrestrial nesting habitat even though marine habitat is believed to be a major contributor to population declines in some regions. To address this information gap, we conducted a 5-year study of marine resource selection by murrelets inWashington, which contains a population experiencing the steepest documented declines and where marine habitat is believed to be compromised....

Boreal forests are critical sinks in the global carbon cycle. However, recent studies have revealed increasing frequency and extent of wildfires, decreasing landscape greenness, increasing tree mortality and declining growth of black and white spruce in boreal North America. We measured ring widths from a large set of increment cores collected across a vast area of interior Alaska and examined implications of data processing decisions for apparent trends in black and white spruce growth. We found that choice of detrending method had important implications for apparent long-term growth...

We assessed the nutritional strategy of true morels (genus Morchella) collected in 2003 and 2004 in Oregon and Alaska, 1 or 2 y after forest fires. We hypothesized that the patterns of stable isotopes (δ13C and δ15N) in the sporocarps would match those of saprotrophic fungi and that radiocarbon (Δ14C) analyses would indicate that Morchella was assimilating old carbon not current-year photosynthate. We compared radiocarbon and stable isotopes in Morchella with values from concurrently collected foliage, the ectomycorrhizal Geopyxis carbonaria (Alb. & Schwein.) Sacc., the saprotrophic...

Under climate change, the reduction of frost risk, onset of warm temperatures and depletion of soil moisture are all likely to occur earlier in the year in many temperate regions. The resilience of tree species will depend on their ability to track these changes in climate with shifts in phenology that lead to earlier growth initiation in the spring. Exposure to warm temperatures (‘forcing’) typically triggers growth initiation, but many trees also require exposure to cool temperatures (‘chilling’) while dormant to readily initiate growth in the spring. If warming increases forcing and...

Forest policymakers and managers have long sought ways to evaluate the capability of forest landscapes to jointly produce timber, habitat, and other ecosystem services in response to forest management. Currently, carbon is of particular interest as policies for increasing carbon storage on federal lands are being proposed. However, a challenge in joint production analysis of forest management is adequately representing ecological conditions and processes that influence joint production relationships. We used simulation models of vegetation structure, forest sector carbon, and potential...

Information on the distribution of rare and little known species is critical for managers and biologists challenged with species conservation in an uncertain future. Pacific Martens (Martes caurina) historically resided throughout Oregon and northern California’s coastal forests, but were considered extinct until 1996 when a population in northern California was rediscovered. Only 26 verified contemporary (1989–2012) records were known within Oregon prior to this survey. The coastal subspecies (M. c. humboldtensis) was petitioned for listing under the federal Endangered Species Act in...

Information on the foraging ecology of animals is important for conservation and management, particularly for keystone species whose presence affects ecosystem health. We examined foraging by an at-risk cavity excavator, the white-headed woodpecker (Picoides albolarvatus). The foraging needs of this species are used to inform management of ponderosa pine (Pinus ponderosa) forests in some areas of western North America. Past observational studies indicated that white-headed woodpeckers forage predominately on cones and trunks of large-diameter (>68 cm) pines in old-growth stands, although...

Martens are small forest carnivores associated with dense, mature forests. These important indicators of a forest’s biodiversity are vulnerable to management activities that open the forest canopy or remove downed debris. Many fuel reduction treatment do just that: dense stands of trees are thinned to minimize fire hazard and future fire severity. Until recently, the effect of these changes to stand structure on marten behavior was unknown. Katie Moriarty, a research wildlife biologist with the Pacific Northwest Research Station, and colleagues recently conducted a study on martens in the...

Many federal, state, and tribal agencies, as well as nonprofit organizations, have recently increased efforts to understand how natural areas can be managed to enhance native pollinators and the ecosystem services they provide. However, managing this important group must be balanced with other services that natural areas provide including hunting, timber production, and livestock grazing. Significant knowledge gaps exist about how to effectively manage habitats used by large ungulates (e.g., cattle (Bos taurus), elk (Cervus elaphus), mule deer (Odocoileus hemionus)) in ways that also...