Treesearch

Biome-scale disturbances by eruptive herbivores provide valuable insights into species interactions, ecosystem-function, and impacts of global change. We present a conceptual framework using one system as a model, emphasizing interactions across levels of biological hierarchy and spatiotemporal scales. Bark beetles are major natural disturbance agents in western North American forests. However, recent bark beetle population eruptions have exceeded the frequencies, impacts, and ranges documented during the previous 125 years. Extensive host abundance and susceptibility, concentrated beetle...

Recent studies with closed-path eddy covariance (EC) systems have indicated that the attenuation of fluctuations of water vapor concentration is dependent upon ambient relative humidity, presumably due to sorption/desorption of water molecules at the interior surface of the tube. Previous studies of EC-related tube attenuation effects have either not considered this issue at all or have only examined it superficially. Nonetheless, the attenuation of water vapor fluctuations is clearly much greater than might be expected from a passive tracer in turbulent tube flow. This study reexamines...

The rapid pace of social and environmental changes over the past few decades has presented significant challenges for the people who manage our public lands. Demographic shifts have placed large populations in close proximity to public lands and have resulted in increased public scrutiny of decision making on those lands. Natural resource managers are required to make informed decisions about multiple resources in complex natural systems in the face of competing and often conflicting objectives and values. The result is that natural resource managers are managing not only resources but...

This report provides an assessment of the effects of climate change on U.S. agriculture, land resources, water resources, and biodiversity. It is one of a series of 21 Synthesis and Assessment Products (SAP) that are being produced under the auspices of the U.S. Climate Change Science Program (CCSP).

Restoration and fuel treatments in the moist forests of the northern Rocky Mountains are complex and far different from those applicable to the dry ponderosa pine forests. In the moist forests, clearcuts are the favored method to use for growing early-seral western white pine and western larch. Nevertheless, clearcuts and their associated roads often affect wildlife habitat, water and soil resources, and scenic values. To address this issue, we are applying and quantifying integrative silvicultural methods and systems that are applicable for regenerating and growing these, and other early...

The National Silviculture Workshop's genesis in 1973 was the result of forward thinking individuals within the Timber Management staff of National Forest Systems. Several national issues of the 1970s including, but not limited to: 1) the passing of the National Forest Management Act, 2) the mandate that all timber removal, reforestation, and timber stand improvement on Forest Service lands be prescribed by trained and certified silviculturists, and 3) a national policy of intensive timber management on Forest Service lands provided the impetus for "National Silviculture Work Conferences"...

Isn't that development new?" is perhaps the phrase most frequently uttered by people who live in the western US. The West, it seems, is sucking Americans into its precious places at a rate that is unparalleled in recent US history. As humans continue to diffuse into the western landscape, they bring their corresponding demands for energy, transportation, water, amenities, and recreation. In the end, they end up transforming, and even destroying, the intense beauty of the land that once attracted them. While his previous book "Atlas of the New West" (Reibsame et al. 1997, WW Norton and...

Fuel biomass samples from southern Africa and the United States were burned in a laboratory combustion chamber while measuring the biomass consumption rate, the fire radiative energy (FRE) release rate (Rfre), and the smoke concentrations of carbon monoxide (CO), carbon dioxide (CO2), and particulate matter (PM). The PM mass emission rate (RPM) was quantified from aerosol optical thickness (AOT) derived from smoke extinction measurements using a custom-made laser transmissometer. The RPM and Rfre time series for each fire were integrated to total PM mass and FRE, respectively, the ratio of...

Forty-four small-scale experimental fires were conducted in a combustion chamber to examine the relationship between biomass consumption, smoke production, convective energy release, and middle infrared (MIR) measurements of fire radiative energy (FRE). Fuel bed weights, trace gas and aerosol particle concentrations, stack flow rate and temperature, and concurrent thermal images were collected during laboratory-controlled burns of vegetative fuels.

Federal land management agencies have spent tens of millions of dollars on post-fire emergency watershed stabilization measures intended to minimize flood runoff, peakflows, onsite erosion, offsite sedimentation, and other hydrologic damage to natural habitats, roads, bridges, reservoirs, and irrigation systems (General Accounting Office 2003). The decision to apply post-fire treatments to reduce runoff and erosion is based on a risk analysis - assessing the probability that damaging floods, erosion, and sedimentation will occur; the values that are at risk for damage; the need for...