Treesearch

We studied xylem anatomy and hydraulic architecture in 14 transgenic insertion events and a control line of hybrid poplar (Populus spp.) that varied in lignin content. Transgenic events had different levels of down-regulation of two genes encoding 4-coumarate:coenzyme A ligase (4CL). Two-year-old trees were characterized after growing either as free-standing trees in the field or as supported by stakes in a greenhouse. In free-standing trees, a 20 to 40% reduction in lignin content was associated with increased xylem vulnerability to embolism, shoot dieback and mortality. In staked trees,...

Reduced lignin content in perennial crops has been sought as a means to improve biomass processability for paper and biofuels production, but it is unclear how this could affect wood properties and tree form. Here, we studied a nontransgenic control and 14 transgenic events containing an antisense 4-coumarate:coenzyme A ligase (4CL) to discern the consequences of lignin reduction in poplar (Populus sp.). During the second year of growth, trees were grown either free-standing in a field trial or affixed to stakes in a glasshouse. Reductions in lignin of up to 40% gave comparable losses in...

Regulation alone cannot solve complex ecological problems on private lands that are managed for diverse uses. Executing coordinated restoration projects at the watershed scale is only possible with the cooperation and commitment of all stakeholders. Locally organized, nonregulatory watershed councils have proven to be a powerful method of engaging citizens from all interest groups in planning and implementing solutions to improve water quality and fish and wildlife habitat. However, guidance on how to keep science at the forefront in these community-based decisionmaking councils has been...

Whitebark pine inhabits some of the most pristine high-elevation areas of the West. Despite being protected from direct human influence, the tree is declining from indirect effects of fire suppression and climate change. As a keystone species, its decline has widespread ramifications. Successful restoration requires understanding the behavioral ecology of Clark’s nutcracker, a bird that plays a key role dispersing whitebark pine seeds. Based on science by Martin Raphael, and Teresa Lorenz.

In Pacific Northwest forests, lichens provide essential winter forage for deer and elk and also nesting materials and habitat for rodents, birds, and invertebrates. Although lichens are often the first organisms to populate a landscape and many species can survive in the most barren environments, lichens with the greatest ecological value tend to be the most sensitive to excess atmospheric nitrogen. In areas with high levels of human-generated nitrogen, ecologically beneficial lichen species are disappearing and "weedy" species are thriving. Because lichen are innately sensitive to...

The red fox is one of the most widespread and adaptable mammals on Earth. In the American West, however, there are populations of native red foxes that occur only in alpine and subalpine habitats, which may be at risk from human-caused and natural pressures. One potential threat is global climate change, which is likely to reduce both the amount and connectivity of suitable habitat for these unique red foxes. Until recently, the evolutionary history of native North American red foxes, which also occur in the boreal forests of Canada and Alaska, was largely speculative. As a doctoral...

Thermal pollution in rivers can be caused by dams, logging, municipal wastewater treatment, and other human activities. High water termperatures stress ecosystems, kill fish, and promote disease and parasites, and so dam operators, timber companies, and municipalities are held responsible for thermal loading caused by their operations. These entities are looking for ways to mitigate environmental damage. When Portland General Electric (PGE) was applying for re-licensing of its extensive hydroelectric project on the Clackamas River in Oregon, questions were raised about whether the company's...

Federal policies direct public-land managers to reduce wildfire risks for urban areas close to wildlands, while broader agency goals call for landscape restoration to create fire-resilient forests. This study used wildfires simulation modeling to examine the tradeoffs between focusing fuel reduction efforts on a wildland-urban interface (WUI) in Oregon’s Blue Mountains versus restoration of overly dense stands in the nearby Wallowa-Whitman National Forest. Alan Ager and Nicole Vaillant, researchers with the Pacific Northwest Research Station, simulated fire effects for thousands of random...

The massive volcanic eruption of Mount St. Helens 31 years ago provided the perfect backdrop for studying the earliest stages of forest development. Immediately after the eruption, some areas of the blast area were devoid of life. On other parts of the volcanic landscape, many species survived, although their numbers were greatly reduced. Reassembly began at many different starting points along the spectrum of disturbance. Within the national volcanic monument, natural regeneration generally has been allowed to proceed at its own pace. Charlie Crisafulli and Fred Swanson, scientists with...

Climate variation exacerbates threats to amphibians such as disease and habitat loss. Yet, by and large existing species- and land-management plans give little if any consideration to climate impacts. Moreover, many management actions that do address emerging climate patterns have yet to be evaluated for feasibility and effectiveness. To help address these needs, research ecologist Dede Olson and her colleagues compiled an array to novel management actions from around the world that aim to mitigate the effects of changing climate conditions on amphibians. One set of approaches focuses on...