Treesearch

Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry, and total N deposition from the Communities Multi-Scale Air Quality model, and 3) ambient particulate N from Interagency Monitoring of Protected Visual Environments (IMPROVE). Sensitive species declines of 20-40% were associated...

Many forest-dwelling species rely on both terrestrial and aquatic habitat for their survival. These species, including rare and little-understood amphibians and arthropods, live in and around headwater streams and disperse overland to neighboring headwater streams. Forest management policies that rely on riparian buffer strips and structurebased management—practices meant to preserve habitat—address only some of these habitat needs. They generally do not consider the overland connectivity necessary for these species to successfully move across a landscape to maintain genetically diverse...

Interactions among plant species and their growth patterns help shape a forest. Various management practices can enhance forest complexity and in return yield benefits that include enhanced growth of desired species, slowing the spread of root disease, and improved wildlife habitat. Based on science by Timothy B. Harrington, Warren Devine

Acre for acre, streams of the coastal temperate rain forest along the Gulf of Alaska export 36 times as much dissolved organic carbon as the world average. Rain and snow are the great connectors, tightly linking aquatic and terrestrial systems of this region. The freshwater that flushes over and through the forest floor leaches carbon and other nutrients from the soil and delivers them to headwater streams. Dissolved organic carbon derived from soils has a large biodegradable component, making it an important food source for freshwater and marine food webs. In the Tongass National Forest...

The decline of oak woodlands is an urgent conservation challenge in the Pacific Northwest. Prior to settlement by Euro-Americans, prairies, oak-dominated savannas, and oak woodlands were abundant in the low-lying areas of the region. Now it’s estimated that 1 to 5 percent of that native oak savanna remains. The rest has been supplanted by pastures, fields, Douglas-fir forests, and development. Experts agree that immediate intervention is needed if Oregon white oak ecosystems are to survive. Based on science by Warren Devine, and Connie Harrington.

Soil exposed to prolonged intense heat during a wildfire turns a distinctive red color. The heat volatilizes soil nutrients and kills subterranean microbial communities. Patches of severely burned red soil are found most frequently in areas that were heavily covered with down, dead wood before the fire. It has long been thought that exposure to such heat sterilized soil, leaving it more susceptible to invasion by nonnative plant species than less severely burned soils. based on science by Jane Smith and Cassie Hebel.

A network of late-successional forest reserves is central to the Northwest Forest Plan, the guiding vision for managing federal forests in Washington, Oregon, and northern California within the range of the northern spotted owl. These reserves were created to maintain older forest structure as habitat for the northern spotted owl, marbled murrelet, and other associated species. Since the plan’s adoption in 1994, however, scientific thinking has evolved to question the ecological suitability of reserves as the primary recovery strategy for the northern spotted owl in the fire-prone forests...

For urban dwellers, trees soften a city’s hard edges and surfaces, shade homes and streets, enhance neighborhood beauty, filter the air, mitigate storm runoff, and absorb carbon dioxide. Trees may even reduce crime and improve human health. However, these benefits have not been well quantified, making it difficult for urban planners and property owners to weigh their costs and benefits or assess tree cover against competing land uses. New research from the Pacific Northwest (PNW) Research Station demonstrates that street trees increase home prices in Portland, Oregon, that shade trees...

Land use change is a key part of global change. Deforestation, urban sprawl, agriculture, and other human influences have substantially altered natural ecosystems and fragmented the global landscape. Slowing down deforestation and afforesting environmentally sensitive agricultural land are important steps for mitigating climate change. Because no policy operates in a vacuum, however, it’s important to consider how separate climate mitigation policies might interact with each other. Based on science by Ralph Alig

The timing of spring budburst in woody plants impacts not only the subsequent seasonal growth for individual trees, but also their associated biological community. As winter and spring temperatures have warmed under the changing climate, in many species budburst has been happening earlier in the year. Understanding the long-term effects of this shift and adapting forest management to accommodate it requires deeper insights into the dynamics of budburst. The researchers investigated this topic in a complex of experiments simulating a range of winter conditions for wide range of genetic...