Treesearch

Foresters are increasingly interested in remote sensing data because they provide an overview of landscape conditions, which is impractical with field sample data alone. Light Detection and Ranging (LiDAR) provides exceptional spatial detail of forest structure, but difficulties in processing LiDAR data have limited their application beyond the research community. Another obstacle to operational use of LiDAR data has been the high cost of data collection. Our objectives in this study were to summarize, at the stand level, both LiDAR- and Landsat (satellite)-based predictions of some common...

There are about 500 species of bark beetles (Coleoptera: Curculionidae: Scolytinae) in the United States (Wood 1982). A number of them are important disturbance agents in forested ecosystems, occasionally creating large tracts of dead trees. One eruptive species is the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, which utilizes Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, as its primary host throughout most of the tree's range. The Douglas-fir beetle is univoltine with brood adults and larvae overwintering (Schmitz and Gibson 1996). The insect prefers to attack large...

A mountain pine beetle outbreak in Colorado lodgepole pine forests has altered stand and fuel characteristics that affect potential fire behavior. Using the Fire and Fuels Extension to the Forest Vegetation Simulator, potential fire behavior was modeled for uninfested and mountain pine beetle-affected plots 7 years after outbreak initiation and 10 and 80% projected tree fall using measured and projected fuel and stand characteristics. Under 90th percentile weather conditions, uninfested plots exhibited proportionally more crown fire than infested plots. Plots predicted to have crown fire...

Understanding the potential of forest ecosystems as global carbon sinks requires a thorough knowledge of forest carbon dynamics, including both sequestration and fluxes among multiple pools. The accurate quantification of biomass is important to better understand forest productivity and carbon cycling dynamics. Stand-based inventories (SBIs) are widely used for quantifying forest characteristics and for estimating biomass, but information may quickly become outdated in dynamic forest environments. Satellite remote sensing may provide a supplement or substitute. We tested the accuracy of...

Our study reports the results of field and garden experiments designed to quantitatively evaluate the impact of herbivory by a weed biological control agent, the stem-mining weevil Mecinus janthinus Germar, on the growth of its exotic host Dalmatian toadflax, Linaria dalmatica (L.) Miller. Herbivory by M. janthinus under both natural and manipulated environmental conditions inhibited L. dalmatica growth. Reductions in stem length, biomass, and growth were more pronounced for plants subjected to both exophagous (adult) and endophagous (larval) feeding injury than for plants exposed only to...

Native sagebrush ecosystems in the Great Basin (western USA) are often invaded following fire by exotic Bromus tectorum (cheatgrass), a highly flammable annual grass. Once B. tectorum is established, higher fire frequencies can lead to local extirpation of Artemisia tridentata ssp. vaseyana (mountain big sagebrush) and have cascading effects on sagebrush ecosystems and the species that depend on them. We conducted a landscape-scale observational study to examine the distribution and cover of B. tectorum and A. tridentata 6 years after a large wildland fire. We used structural equation...

Climate change poses a challenge for resource managers as they review current management practices. Adaptation is a critical means of addressing climate change in the near future because, due to inherent time lags in climate impacts, the effects of increased atmospheric greenhouse gases will be felt for decades even if effective mitigation begins now. To address the impacts of climate change, land managers need techniques for incorporating adaptation into ongoing or pending projects. Here we present a new tool for integrating climate change considerations into project planning. We designed...

White pine blister rust is an exotic, invasive disease that severely damages and kills white pines in the southern Rocky Mountains. We evaluated the efficacy of preventive pruning (removing lower branches) and/or sanitation pruning (removing cankered branches) to reduce disease impacts in limber (Pinus flexilis James) and Rocky Mountain bristlecone (P. aristata Englm.) pine in two recreation areas in the southern Rocky Mountains. We compared the benefits of the different pruning techniques based on the distribution and severity of cankers, tree height class (small = 30 ft), and treatment...

Understanding resource selection by elk (Cervus elaphus) at multiple spatial scales may provide information that will help resolve the increasing number of resource conflicts involving elk. We quantified vegetation at 412 sites where the precise location of elk was known by direct observation and 509 random sites in the Black Hills of South Dakota during 1998-2001. We obtained stand level variables from geographic information system coverages for a 250 m buffer around elk and random sites. We used classification and regression trees to simultaneously evaluate environmental thresholds of...

Western juniper (Juniperus occidentalis) woodlands in Oregon have expanded four-fold from 600,000 ha in 1930 to > 2.6 million ha, often resulting in the reduction and fragmentation of sagebrush (Artemisia spp.) communities. We documented dynamics of western juniper across the John Day Ecological Province in central Oregon by recording size class and growth form at 178 sites. We used stratified random sampling, with strata based on vegetation association (sagebrush, juniper, other) and distance from juniper stands. Only 26 percent of sites contained pre-settlement trees (in other words, >...