Treesearch

Few seed sources of North American forbs are available for revegetation/restoration of degraded western rangelands adapted to annual precipitation zones less than 300mm, and those that are available are mainly wildland collected. The amount of time and resources necessary to make wildland collections in quantity results in high seed prices and variable seed quality, such that forbs have been under-represented in rangeland seeding mixes. We have previously identified western prairie clover (Dalea ornata Douglas ex Hook.), Searls’ prairie clover (Dalea searlsiae A. Gray), and basalt milkvetch...

Three natural-track selected germplasms of Searls’ prairie clover (Dalea searlsiae (A. Gray) Barneby [Fabaceae]) have been released by the USDA’s Agricultural Research Service (ARS) for use in revegetation and restoration of semiarid rangelands in the western US. Searls’ prairie clover is a perennial leguminous forb that is native to Utah, Nevada, Arizona, and California. Data from common-garden and DNA-marker studies were used to develop and document these releases. The ARS Forage and Range Research Laboratory was asked by the USDI Bureau of Land Management (BLM) and Colorado Plateau land...

Many cities are making substantial capital investments in urban tree planting. Residents play active and diverse roles in enhancing and protecting the urban forest, and are therefore critical to many municipal-level policy objectives. The way residents perceive and value the urban forest can have implications for achieving urban forestry goals through residents and volunteers. However, urban residents are not a monolithic block or homogenous category; instead, they have diverse opinions, needs, and constraints. Moreover, relatively little is known about how residents hear about available...

Belowground biomass is thought to account for much of the total biomass in mangrove forests and may be related to soil fertility. The Yela River and the Sapwalap River, Federated States of Micronesia, contain a natural soil resource gradient defined by total phosphorus (P) density ranging from 0.05 to 0.42 mg cm−3 in different hydrogeomorphic settings. We used this fertility gradient to test the hypothesis that edaphic conditions constrain mangrove productivity through differential allocation of biomass to belowground roots. We removed sequential cores and implanted root ingrowth bags to...

Terrestrial ecosystems provide important resources for many human uses, however, these resources are threatened by nitrogen from air pollution. Identifying reductions in air pollution that will protect ecosystems is the main focus of the mitigation strategies currently being developed in the United States.

Accurately estimating evapotranspiration (ET) is essential for orchard managers to design irrigation schedules and conserve water resources in semi-arid environments where water is often the limiting factor for successful production. Improving water use efficiency helps irrigation scheduling and thus benefits water resource management and the sustainability of the local economy. This study examined three existing ET models that were developed based on the Shuttleworth- Wallace model (SW) for estimating ET from sparsely covered crops in the arid Shiyang River basin (mean annual precipitation...

The riparian forests of interior and south-central Alaska are arguably the most productive and important ecosystems within the portion of the State covered by the boreal forest. Recent large-scale mortality of thin-leaf alder (Alnus icana tenuifolia), one of the dominant species in these areas, has created the potential for deep-seated changes in these ecosystems. Alder is a symbiotic nitrogen-fixer, allowing it to thrive in low-nutrient soil. The long-term productivity of Alaskan riparian forests is directly related to the amount of nitrogen fixed and deposited in the soil during the...

Extensive outbreaks of mountain pine beetle (MPB), spruce beetle (SB), and other insects are altering forest stand structure throughout the Western United States, and thereby increasing the natural heterogeneity of fuel distribution. Riparian forests frequently occur as narrow linear features in the landscape mosaic and can contribute to the spatial complexity of forest stands and fuel loads. These streamside forests are valued for providing aquatic and terrestrial habitat, serving as sources of in-stream and floodplain large wood, and maintaining streamside microclimates and stream water...

Tree crown conditions are visually assessed by the U.S. Department of Agriculture Forest Service, Forest Inventory and Analysis (FIA) Program as an indicator of forest health. These assessments are useful because an individual tree’s photosynthetic capacity is dependent upon the size and condition of its crown. In general, trees with full, vigorous crowns are associated with more vigorous growth rates (Zarnoch and others 2004), and when trees undergo stress, the first symptoms are often visible in the crown. Furthermore, tree crowns form the overstory structure of the forest and directly...

Beech bark disease (BBD) remains the most serious threat to American beech (Fagus grandifolia) in its native range. Pathologists have historically described BBD as a predictable interaction between the Cryptococcus fagisuga scale insect and a Neonectria canker-forming fungus. It is well known that beech trees infested by C. fagisuga become predisposed to Neonectriacolonization (Houston and O’Brien 1983).