Treesearch

Numbers of Bell's Vireos (Vireo beltii) have declined throughout much of the breeding range in recent years, yet little information exists to determine factors that are causing these declines. We studied Bell's Vireos nesting in grassland-shrub habitats at two study areas in central Missouri to determine reproductive performance, survival, and population growth potential. Birds were color banded and observed during the breeding seasons of 1996, 1997, and 1998 to determine seasonal fecundity. We monitored 124 breeding pairs (127 pair years) and 213 nests. Density declined from 1.00 to 0.80...

Environmental awareness has increased in the past two decades. One factor believed to influence this awareness is outdoor recreation participation. We examined whether participation in outdoor recreation predicts pro-environmental behavior and whether environmental values mediate the relationship. A survey of residents of Washington state measured (a) participation in outdoor recreation, (b) environmental values, and (c) proenvironmental behavior. Factor analysis of recreation activities resulted in the following four "types": "resource-utilization" activities, "nature-appreciation"...

A large sample of national news media stories about the Tongass National Forest--covering January 1, 1985, through July 31, 1997--was analyzed using the InfoTrend software and method. The main purpose of the analysis was to explore the national-level benefits and values reflected in news accounts about the Tongass. Results indicate that the nature of social debate about management of the Tongass was consistent over the 12-year period, focusing mainly on the clash between commodity-related benefits (timber harvest) and ecosystem benefits and values. Media discussion of recreation and...

Ecosystem restoration efforts are increasing throughout the United States and in many places around the world. Many of these efforts are undertaken with the support and cooperation of local residents, interest groups, and government agencies. However, some restoration efforts are meeting with public resistance, and conflicts between various individuals and groups are resulting in controversies about whether and how ecological restoration should be carried out on public lands.

Three factors, human population density, topography,and culture interact to create temporal and spatial differences in the frequency of fire at the landscape level. These facters can be quantitatively related to fire frequency. The fire model can be used to reconstruct historic and to predict future frequency of fire in ecosystems, as well as to identify long-term changes in anthropogenic fire regimes. Topographic roughness is positively related by a regression equation to the length of mean fire intervals indicating that fires are less frequent in rough than in flat terrain during periods...

Capture, marking and release of birds began at the end of the 19th century and has increased in application to better understand the natural history of birds. The method of leg banding (or "ringing" in Europe) is now widely accepted as the primary means for determining movements, longevity, and individual performance of birds. By recapturing birds or using remote identification methods through auxiliary marking techniques, investigators can follow individuals over time and even determine lifetime reproductive success (LRS). Although LRS studies are difficult (Newton 1992 identified only 23...

The episodic or flushing growth habit of northern red oak (Quercus rubra L.,) has a significant influence on carbon fixation, carbon transport from source leaves, and carbon allocation within the plant; however, the impact of episodic growth on carbon parciprioning among chemical fractions is unknown. Median-flush leaves of the first and second flush were photosynthetically labeled with 14CO and partitioning of 14C into lipids and pigments, sugars, amino acids, organic acids, protein, starch, and structural carbohydrates of source leaves, stem, and roots was determined. In addition, four...

Tree root activity, including fine-root production, turnover and metabolic activity are significant components of forest productivity and nutrient cycling. Differences in root activity among forest types are not well known. A 3-year study was undertaken in red pine (Pinus resinosa Ait.) and hybrid poplar (Populus tristis X P. balsamifera cv 'Tristis no. 1') plantations to compare belowground root dynamics. We measured fine-root production, mortality and standing crop, as well as soil CO2 efflux. Pine fine-root production was only 2.9% of that of poplar during three years: 85 pine roots...

Permanent plots in old-growth hemlock-northern hardwood forests of Michigan's upper peninsula have been remeasured over periods of 16-32 yr. A gradient from hemlock (Tsuga canadensis) to sugar maple (Acer saccharum) dominance is associated with increasing soil pH and calcium. Secondary species include yellow birch (Betula alleghaniensis) and basswood (Tilia americana). From 1962 to 1994 hemlock increased in basal area and dominance in most plots. Sugar maple showed little overall change, while basswood and especially yellow birch showed sporadic but often large declines in basal area,...

A recessive mutation was identified that constitutively activated the ethylene response pathway in Arabidopsis and resuited in a rosette-lethal phenotype. Positional cloning of the gene corresponding to this mutation revealed that it was allelic to responsive to antagonist1 (ran1), a mutation that causes seedlings to respond in a positive manner to what is normally a competitive inhibitor of ethylene binding. In contrast to the previously identified ran 1-1 and ran1-2 alleles that are morphologically indistinguishable from wild-type plants, this ran 1-3 allele results in a rosette-lethal...