Treesearch

Sulfur cinquefoil (family Rosaceae) is an invasive, herbaceous perennial, native to Eurasia. It has wide ecological amplitude and has become established throughout North America in numerous habitat types. Sulfur cinquefoil reproduces only by seed (achenes); however, little is known about its regenerative strategy or reproductive biology. To improve understanding of the mechanisms of expansion for sulfur cinquefoil, we quantified seed production and measured seed dispersal at sites infested with sulfur cinquefoil in different habitats in northeast Oregon. Seed dispersal was measured by...

Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.)-conifer riparian forests (40 years old) in southeast Alaska. More riparian red alder were found along streams affected by both timber harvesting and mass movement than in streams affected by timber harvesting alone. Young-growth stands produced little large wood material (diameter >10 cm) and had little effect on altering the size distribution of...

Permafrost melting is occurring in areas of the boreal forest region where large amounts of carbon (C) are stored in organic soils. We measured soil respiration, net CO2 flux, and net CH4 flux during May-September 2003 and March 2004 in a black spruce lowland in interior Alaska to better understand how permafrost thaw in poorly drained landscapes affects land-atmosphere CO2 and CH4 exchange. Sites included peat soils underlain by permafrost at ~O.4 m depth (permafrost plateau, PP), four thermokarst wetlands (TW) having no permafrost in the upper 2.2 m, and peat soils bordering the thermokar...

Herbivory is an important ecological process in forest canopies but is difficult to measure, especially for whole stands. We used the Wind River Canopy Crane in Washington State to access 101 randomly located sample points throughout the forest canopy. This provided a relatively quick and convenient way to estimate herbivory for a whole stand. The overall level of herbivory was estimated at 1.6 percent of leaf area. The distribution was strongly skewed to the lower canopy where broad-leafed species experienced higher levels of herbivory. Herbivory averaged 0.3 percent in conifers and 13.5...

Social science methods can be used to assess how the public values contextsensitive solutions. The roadside landscape is a public lands resource that has many functions and provides many benefits. Diverse stakeholders may have varied expectations for roadside design. The urban forest is often a contested component of the urban roadside. Two research surveys based on landscape assessment literature were used to assess and quantify public preferences and perceptions with regard to trees in highspeed and freeway roadsides. One photo questionnaire was distributed in urban areas nationally and...

In the mid to late 20th century, U.S. transportation agencies focused on traffic planning and design practices intended to achieve high levels of traffic capacity and safety for roads at lowest cost. Intangible values of the roadside such as community character and environmental systems were often overlooked, including the urban forest. Context Sensitive Solutions is a U.S. national policy intended to better incorporate local community values into transportation planning processes and products. The starting point for community-based roadside design is adequate research. This study analyzed...

We investigated the landscape distribution and spatial patterns of western hemlock dwarf mistletoe in old-growth and mature Douglas-fir forests of the Wind River Experimental Forest. The study was conducted in two settings: the old-growth forest (500 year) of the 478-ha T.T. Munger Research Natural Area (T.T. Munger RNA) and the higher elevation, predominantly 157-year-old stand of the 1400-ha Panther Creek Division of the Wind River Experimental Forest. Existing transects and tagged trees were used in the T.T. Munger RNA to survey for dwarf mistletoe infection. Eighty-three percent of the...

An interregional trading model for roundwood products was developed that recognizes the importance of demand centers (centers of forest products manufacturing activity) and inventory in forecasting future harvests and trade flows. A gravity model was constructed that considers the relative position of each region vis-a-vis all others as a producer of stumpage and as a consumer of roundwood products. The gravity model was incorporated in a multiregion version of DPSupply referred to as the Interregional DPSupply System (IDPS). Projections for growth, harvest, and trade in forest products...

The amount, physical characteristics, and spatial distrubution of attached dead branches in the canopy of 450-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) trees were studied over a 5-year period to quanitfy their contribution to the canopy wood detritus pool of an old-growth Douglas-fir-western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest in the western Washington Cascades. We developed a five-class decay rating for attached dead branches. From the size distribution and relative amounts and vertical distribution of attached dead branches in the five decay...

Freshwater midges, consisting of Chironomidae, Chaoboridae, and Ceratopogonidae, were assessed as a biological proxy for palaeoclimate in eastern Beringia. The northwest North American training set consists of midge assemblages and data for 17 environmental variables collected from 145 lakes in Alaska, British Columbia, Yukon, Northwest Territories, and the Canadian Arctic Islands. Canonical correspondence analyses (CCA) revealed that mean July air temperature, lake depth, arctic tundra vegetation, alpine tundra vegetation, pH, dissolved, organic carbon, lichen woodland vegetation, and...