Treesearch

Peripheral populations are often of increased conservation value; however, knowledge of the ecological and evolutionary consequences of a peripheral location is poor. Spatial dynamics are often interpreted as strategies to maximize access to fitness-limiting resources. Red squirrels Tamiasciurus hudsonicus are territorial in western portions of their range and exhibit overlapping home ranges in eastern forests. Endangered Mt. Graham red squirrels T. hudsonicus grahamensis represent the southernmost extension of the species. We used radiotelemetry to assess space use and interindividual...

An accelerated decline of aspen occurred across the Coconino National Forest, in northern Arizona, following a frost event in June 1999, and a long-term drought that included an extremely dry and warm period from 2001 through 2002, and bouts of defoliation by the western tent caterpillar in 2004, 2005, and 2007. From 2003 to 2007, we monitored aspen mortality and regeneration, and measured associated stand and site variables on randomly-selected sites of the Coconino National Forest where aerial survey had detected dieback or decline. Year of death was observed or estimated since 2000....

The 7th International Conference on Dendrochronology - Cultural Diversity, Environmental Variability was held in Beijing, China from 11 to 17 June 2006. The conference was organized and hosted by the Institute of Botany, Chinese Academy of Sciences (IB_CAS) in conjunction with the International Union of Forest Research Organizations (IUFRO) Working Group 5.01.07 (Tree-Ring Analysis) and under the auspices of the Tree-Ring Society (TRS) and the European Association for Tree-Ring Research (ATR). It was also sponsored by the National Natural Science Foundation of China (NSFC), the Chinese...

We present results on survival of ponderosa pine and reduction in dwarf mistletoe (Arceuthobium) infection after six operational prescribed underburns in New Mexico. Survival 3 years postburn for 1,585 trees fit a logistic relationship with crown scorch, bole char, and mistletoe. The scorch effect was best represented by classes as <90, 90, and 100%; char as char-squared; and mistletoe as DMR <5, 5, and 6. Survival ranged from over 90% for trees with DMR <5 and scorch <90% to almost 0% for trees with DMR 6 and scorch 100%. The proportion of surviving infected trees with reduction in DMR...

In September 2007, a collaborative effort was made to survey Armillaria species in three general areas of south-central Mexico. Collected Armillaria isolates will be subjected to DNA analyses to examine genetic relationships with other Armillaria species. These studies will provide baseline information for examining evolution of Armillaria spp., assessing potential for hybridization or invasive species risk of Armillaria spp., and evaluating potential impacts of climate change. During this trip, observations were also made that may provide insights to other forest diseases, such as Annosus...

We review modelling approaches in relation to three key areas of sciurid ecology: management, disease risk assessments and conservation. Models enable us to explore different scenarios to develop effective management and conservation strategies. They may also assist in identifying and targeting research needs for tree and flying squirrels. However, there is a need to refine techniques and assure that data used are applicable at the appropriate scale. Models allow managers to make informed decisions to help conserve species, but success requires that the utility of the tool be evaluated as...

The fire destruction of hundreds of homes associated with wildfires has occurred in the United States for more than a century. From 1870 to 1920, massive wildfires occurred principally in the Lake States but also elsewhere. Wildfires such as Peshtigo (Wisconsin, 1871), Michigan (1881), Hinckley (Minnesota, 1894), Adirondack (New York, 1903), the Big Blowup (Idaho-Montana, 1910), and Cloquet (Minnesota, 1918) extended across millions of acres, destroying towns and causing several thousand civilian fatalities. This period produced significantly greater destruction of property and lives than...

Predicting the global carbon and water cycle requires a realistic representation of vegetation phenology in climate models. However most prognostic phenology models are not yet suited for global applications, and diagnostic satellite data can be uncertain and lack predictive power. We present a framework for data assimilation of Fraction of Photosynthetically Active Radiation absorbed by vegetation (FPAR) and Leaf Area Index (LAI) from the MODerate Resolution Imaging Spectroradiometer (MODIS) to constrain empirical temperature, light, moisture and structural vegetation parameters of a...

Federal land managers desire seed of Great Basin perennial wildflowers, mixed with grass and shrub seed, for restoration of millions of acres of sagebrush communities degraded by altered wildfire regimes, and exotic grasses and forbs. For 15 candidate wildflower species to be farmed for seed production, all were found to need pollinators, typically bees (Apiformes), for fruit and seed production. Some can be pollinated with currently managed bees (honey bees, alfalfa leaf-cutting bees), but for others, management protocols and starting populations are being developed for suitable species...

The terrestrial ecosystems of the North American continent represent a large reservoir of carbon and a potential sink within the global carbon cycle. The recent State of the Carbon Cycle Report [U.S. Climate Change Science Program (CCSP), 2007] identified the critical role these systems may play in mitigating effects of greenhouse gases emitted from fossil fuel combustion. However, there are currently large uncertainties in continental carbon models, and the scientific community's understanding of relevant carbon sources and sinks has been much less complete in Mexico than in Canada and...