Treesearch

This report was produced by a group of scientists who were invited by the U.S. Forest Service to synthesize the current scientific literature to answer an important question facing the managers of federal and private lands in many parts of the country. The question was: What potential cumulative environmental effects at the watershed scale might be caused by implementing land management activities that reduce forest fuels on large scales? The main body of this report is a compilation of what they found, including both what can and cannot be concluded from the current science.

The public land management agencies are phasing in a radically new approach to land management. They are shifting from their focus on individual resources to a more holistic approach of managing whole ecosystems. Fire-excluded systems are prone to changes in composition and density and are susceptible to catastrophic fire and invasion by non-native species. The cause of the problem in many areas includes more than a century of fire exclusion and suppression along with increased human development at the wildland-urban interface. Grazing and logging have also contributed to this problem.

Attack by pathogens can have ecological consequences for plants at many scales, such as the individual, population and community scale, although the latter is the least studied. Community-level consequences of disease in natural plant communities can drive facilitation in succession (Van der Putten, Van Dijk & Peters 1993), maintain species diversity in tropical rain forest (i.e. Janzen-Connell hypothesis; Clark & Clark 1984) and promote exotic invasion via negative feedback loops (Callaway et al. 2004). The pathogens involved in the above community-level interactions are often restricted...

In a parallel study, ten small watersheds (about 5 ha) were installed in the Priest River Experimental Forest (PREF) in northern Idaho, and another ten were installed in the Boise Basin Experimental Forest (BBEF) in central Idaho. The long-term objective of the study is to compare the effects of different forest management activities on runoff and sediment delivery. This paper reports the observed runoff hydrographs and amounts and the sediment yields during the first 3 to 4 years of the study. During the first 3 years, none of the watersheds received any management treatments or natural...

Mobile scanning lidar is the most appropriate tool for monitoring wildfire smoke-plume dynamics and optical properties. Lidar is the only remote sensing instrument capable of obtaining detailed three-dimensional range-resolved information for smoke distributions and optical properties over ranges of 10+ km at different wavelengths simultaneously.

The methodology of using mobile scanning lidar data for investigation of smoke plume rise and high-resolution smoke dispersion is considered. The methodology is based on the lidar-signal transformation proposed recently [Appl. Opt. 48, 2559 (2009)]. In this study, similar methodology is used to create the atmospheric heterogeneity height indicator (HHI), which shows all heights at which the smoke plume heterogeneity was detected by a scanning lidar. The methodology is simple and robust. Subtraction of the initial lidar signal offset from the measured lidar signal is not required. HHI...

We present an alternative method for determining the total offset in lidar signal created by a daytime background-illumination component and electrical or digital offset. Unlike existing techniques, here the signal square-range-correction procedure is initially performed using the total signal recorded by lidar, without subtraction of the offset component. While performing the square-range correction, the lidarsignal monotonic change due to the molecular component of the atmosphere is simultaneously compensated. After these corrections, the total offset is found by determining the slope of...

Biomass burning is a significant source of carbonaceous aerosol in many regions of the world. When present, biomass burning particles may affect the microphysical properties of clouds through their ability to function as cloud condensation nuclei or ice nuclei. We report on measurements of the ice nucleation ability of biomass burning particles performed on laboratory-generated aerosols at the second Fire Lab at Missoula Experiment. During the experiment we generated smoke through controlled burns of 21 biomass fuels from the United States and Asia. Using a Colorado State University...

We characterized the gas- and speciated aerosol-phase emissions from the open combustion of 33 different plant species during a series of 255 controlled laboratory burns during the Fire Laboratory at Missoula Experiments (FLAME). The plant species we tested were chosen to improve the existing database for U.S. domestic fuels: laboratory-based emission factors have not previously been reported for many commonly burned species that are frequently consumed by fires near populated regions and protected scenic areas. The plants we tested included the chaparral species chamise, manzanita, and...

An important policy question receiving considerable attention concerns the risk perception-risk mitigation process that guides how individuals choose to address natural hazard risks. This question is considered in the context of wildfire. We analyze the factors that influence risk reduction behaviors by homeowners living in the wildland-urban interface. The factors considered are direct experience, knowledge of wildfire risk, locus of responsibility, fulltime/seasonal status, and self-efficacy. Survey data from three homeowner associations in the western U.S. are used to estimate the...