Treesearch

Observations during the 2006 dry season of highly elevated concentrations of cyanides in the atmosphere above Mexico City (MC) and the surrounding plains demonstrate that biomass burning (BB) significantly impacted air quality in the region. We find that during the period of our measurements, fires contribute more than half of the organic aerosol mass and submicron aerosol scattering, and one third of the enhancement in benzene, reactive nitrogen, and carbon monoxide in the outflow from the plateau. The combination of biomass burning and anthropogenic emissions will affect ozone chemistry...

Climate changes in the Prairie Potholes and Grasslands bioregion include increased seasonal, annual, minimum, and maximum temperature and changing precipitation patterns. Because the region is relatively dry with a strong seasonal climate, it is sensitive to climatic changes and vulnerable to changes in climatic regime. For example, model simulations show that regional drought in the Prairie Pothole Region may result in loss of valuable habitat for breeding waterfowl, from an area that historically has produced 50-80% of the continent's ducks. Other impacts include potential vegetation...

Slope stabilization treatments are frequently applied following high severity wildfires to reduce erosion, protect water quality, and mitigate threats to human life and property. However, the effectiveness of many treatment options has not been well established. Furthermore, treatments may unintentionally inhibit natural vegetation recovery or facilitate exotic species invasion, compromising long-term ecosystem function. We evaluated the effects of seeding and fertilization treatments on plant cover and vegetation recovery following the Deer Point fire in the Eastern Cascade Mountains of...

Morphometric analysis of Simrad EM300 multibeam bathymetric DEMs reveals details of deformation patterns in a ~145 km2 submarine landslide complex that are commonly associated with slow-moving earthflows in terrestrial settings. This mode of failure, where existing landslide debris is remobilised repeatedly along discrete shear boundaries and is progressively conveyed through the complex, has not previously been recognised in the submarine environment. The kinematics contrast with the more traditional models of submarine landslide complex development in which repeated catastrophic failures...

Limber pine, Pinus flexilis James, is characterized by a patchy distribution that displays metapopulation dynamics and spans a broad latitudinal and elevational range in North America (Webster and Johnson 2000). In the southern Rocky Mountains limber pine grows from below the forest-grassland ecotone up to the forest-alpine ecotone, from ~1600 m above sea level in the short grass steppe to > 3300 m at the continental divide (Schoettle and Rochelle 2000). In this region, limber pine's altitudinal range is wider than any of its co-occurring tree species. Limber pine ecosystems serve a...

The effect of climate change on ecosystem structure, function, and services will depend on the ecosystem's degree of sensitivity to climate change, the natural ability of plants and animals to adapt, and the availability of effective management options. Sensitivity to climate change is a function of ecosystem health and environmental stresses such as air pollution and invasive species. In nature, adaptation occurs as plants and animals react to environmental changes, including climate. Natural adaptation comes about through genetic changes, changes in phenology, and changes in behavior.

We compare two approaches to mitigating hypothetical bias. The study design includes three treatments: an actual payment treatment, a contingent valuation (CV) treatment with a followup certainty question, and a CV treatment with a cheap talk script. Our results suggest that both the follow-up certainty treatment and the cheap talk treatment produce willingness-to-pay (WTP) estimates consistent with the actual payment treatment. However, the follow-up certainty treatment provides response distributions at all offer amounts that are statistically similar to the actual payment treatment,...

Desertification, caused by land degradation as opposed to the immediate creation of classical deserts, is of prime concern in the 21st century. As a result of human activities and climate change, the land loses its proper hydrologic function and biological productivity. Desertification affects 33 % of the earth's surface and over a billion people. Fire-related desertification has a number of environmental, social, and economic consequences. The two key environmental consequences are soil erosion and non-native plant invasions. Erosion after wildland fires can be in the range of <1 Mg ha-1...

Recreation ecology, the study of environmental consequences of outdoor recreation activities and their effective management, is a relatively new field of scientific study having emerged over the last 50 years. During this time, numerous studies have improved our understanding of how use-related, environmental and managerial factors affect ecological conditions and processes. Most studies have focused on vegetation and soil responses to recreation- related trampling on trails and recreation sites using indicators such as percent vegetation cover and exposed mineral soil. This applied...

Differential responses by species to modern perturbations in forest ecosystems may have undesirable impacts on plant-animal interactions. If such disruptions cause declines in a plant species without corresponding declines in a primary seed predator, the effects on the plant could be exacerbated. We examined one such interaction between Pinus albicaulis (whitebark pine), a bird-dispersed, subalpine forest species experiencing severe population declines in the northern part of its range, and Tamiasciurus hudsonicus (red squirrel), an effcient conifer seed predator, at 20 sites in two...