Treesearch

Private forestlands in the United States face increasing pressures from growing populations, resulting in greater numbers of people living in closer proximity to forests. What often is called the "wildland/urban interface" is characterized by expansion of residential and other developed land uses onto forested landscapes in a manner that threatens forestlands as productive socioeconomic and ecological resources. Prevailing hypotheses suggest that such forestlands can become less productive, because forest owners reduce investments in forest management. We develop empirical models describing...

Xerophyllum tenax is a mass-flowering, nectarless herb in which self-pollination is unavoidable as anthers shed pollen onto the three, receptive stigmatic ridges attached to each pistil within a few hours after expansion of the perianth. We compared the pollination system with reproductive success in this species through controlled, hand-pollination experiments. Ovaries of flowers sampled from unbagged inflorescences were visited by pollen-eating flies (primarily members of the family Syrphidae), beetles (primarily Cosmosalia and Epicauta spp.), and small bees, and produced normal-sized...

Understanding and managing those mechanisms that affect population dynamics comprise, perhaps, the most fundamental aspect of wildlife management (Caughley 1977). Biologists generally categorize these mechanisms as either top-down (predator-driven) or bottom-up (habitat- or animal-density driven). Bottom-up influences involve imbalances between increasing animal density and key habitat resources. For large ungulates, abundance and nutritive value of forage are commonly thought to be the primary mediators of bottom-up regulation (Caughley 1979, McCullough 1984). Certainly, nutritional...

Research on Anderson and Scherzinger's hypothesis that spring cattle grazing can positively affect subsequent nutritional characteristics of grasses have generated mixed results. Our objectives were: 1) to evaluate fall/winter nutritional indices of bluebunch wheatgrass (Agropyron spicatum [Pursh] Scribn. & Smith), Idaho fescue (Festuca idahoensis Elmber.), and bottlebrush squirreltail (Sitanion hystrix (Nutt.) Smith) in ungrazed, lightly grazed (33% utilization), or heavily grazed (69% utilization) pastures stocked with cattle at the boot stage of growth; and 2) to quantify opportunity...

Wildland fire has been perhaps the most vexing forest management and policy issue in the United States in recent years, stirring both passionate and reasoned debate among managers, policymakers, researchers, and citizens alike. Years of fire suppression and increasing constraints on natural and prescribed burning, possibly along with climate change, have altered historical wildfire regimes resulting in increased wildfire severity in the Nation’s forests. The growing wildfire threat has motivated increasing interest in reducing hazardous fuels through prescribed burning, thinning, and...

This issue of the journal of Forestry is devoted to articles about forestland values. Viewed broadly, natural resources and humans are our two basic resources. An expression of the importance of land as a foundation for forest ecosystems is forestland value. Our attitudes about land and the forest ecosystems that they support have changed considerably in recent years. In earlier decades, forestland value as expressed by markets was mainly a private land issue, driven by the value of standing timber and the bare land's capability to produce subsequent crops of timber.

Functional convergence in hydraulic architecture and water relations, and potential trade-offs in resource allocation were investigated in six dominant neotropical savanna tree species from central Brazil during the peak of the dry season. Common relationships between wood density and several aspects of plant water relations and hydraulic architecture were observed. All species and individuals shared the same negative exponential relationship between sapwood saturated water content and wood density. Wood density was a good predictor of minimum (midday) leaf water potential and total daily...

Huckleberries are major components of the understory vegetation in coniferous Pacific Northwest forests of the United States. Vaccinium species also have a long history of human use. However, little research has been done to ascertain how they respond to common forest management practices. We used data obtained from old-growth, young thinned, and young unthinned Douglas-fir stands in western Oregon to evaluate how forest management could potentially influence species abundance and product supply. Our analysis focused on three species: Vaccinium ovatum, V. parvifolium, and V. membranaceum....

Understanding the shifts over time in the distribution and amount of forest vegetation types in relation to forest management and environmental conditions is critical for many policy and ecological questions. Our objective was to assess the influences of ownership and environment on changes !n forest vegetation from post-settlement historical to recent times in the central Coast Range of Oregon. We evaluated land cover types on 1475 20 m plots, using scanned, geo-referenced historical (1939) and recent (1993) aerial photos. The amount of older conifer cover declined by 63% relative to its...

FIA BioSum, a tool developed by the USDA Forest Services Forest Inventory and Analysis (FIA) Program, generates reliable cost estimates, identifies opportunities and evaluates the effectiveness of fuel treatments in forested landscapes. BioSum is an analytic framework that integrates a suite of widely used computer models with a foundation of attribute-rich, statistically representative sample data for forested landscapes. The framework builds the analysis using comprehensive forest condition data collected by the FIA Program and GIS transportation layers that represent the costs of moving...