Treesearch

On 17 May and 27 June 2011 severe cyclonic storms damaged several hundred hectares of spruce forest (Picea schrenkiana) in the Tian Shan Mountains. Bark beetle populations increased rapidly in dead and damaged trees, particularly Ips hauseri, I. typographus, I. sexdentatus, and Piiyogenesperfossus (all Coleoptera: Curculionidae), and there is concern about the likelihood of a catastrophic bark beetle outbreak. Little is known about the frequency, extent, or severity of either large storm events or bark beetle outbreaks in the Tian Shan Mountains. The ecology and outbreak dynamics of I....

For species with irruptive population behavior, dispersal is an important component of outbreak dynamics. We developed and parameterized a mechanistic model describing mountain pine beetle (Dendroctonus ponderosae Hopkins) population demographics and dispersal across a landscape. Model components include temperature-dependent phenology, host tree colonization determined by an Allee effect, and random-walk dispersal with motility conditioned by host tree density. The model was parameterized at a study site in central Idaho, United States (US), and evaluated at an independent site in...

Limitations inherent to airborne laser scanning (ALS) technology and the complex sorting and packing relationships of forests complicate accurate remote sensing of mid- and understory trees, especially in denser forest stands. Self-similarities in rank-sized individual tree distributions (ITD), e.g. bole diameter or height, are a well-understood property of natural, non-plantation, forests undergoing density dependent self-thinning and thus offer an approach to solving this problem. Alternately, semi-arid conifer forests of the southwestern USA that experience episodic wildfires and...

On February 2, 1912, Aldo Leopold (1887-1948) wrote to his fiancee, Estella Bergere, in Santa Fe that the Forest Service had appropriated $650 to build a new supervisor's quarters he had designed at Tres Piedras, New Mexico, northwest of Taos. At the time, Leopold was about to become the new Forest Supervisor of the Carson National Forest in Tres Piedras. Later that year, he built the house, which the newly married couple decided to call "Mi Casita."

Armillaria species have a global distribution and play variable ecological roles, including causing root disease of diverse forest, ornamental and horticultural trees. Accurate identification of Armillaria species is critical to understand their distribution and ecological roles. This work focused on characterizing an unidentified Armillaria isolate from a Serbian forest using pairing, sequencing of the partial large subunit and intergenic spacer-1 regions of rDNA (LSU-IGS1) and the translation elongation factor-1 alpha gene (tef-1a) genes, and phylogenetic analyses. Despite previously...

National law and policy direct the management of the National Forests, with restoring resilient forest conditions being an overarching theme. Climate is a major driver of disturbances that affect ecosystems, especially those with vegetation that show large departures from historical conditions. Drought, fire, insects, and diseases are common forest stressors whose impacts are being exacerbated by climate change. These stressors are threatening the ecosystem services that people value in the forests of the northern Rocky Mountains. The forests of most concern are the dry ponderosa pine and...

The 1910 fires, which burned more than 1.3 million ha of northern Rocky Mountain forests, provided a mission and management objectives for the newly created Forest Service. By 1911, the Priest River Experimental Station (Forest- PREF) was established in northern Idaho to help meet the needs of the Forest Service. Harry T. Gisborne, whose work was centered at PREF, proved to be one, if not the most influential and far-seeing fire researcher in the history of the Forest Service. Examples of his contributions include the fire danger rating system, fuel moisture sticks, short- and long-term...

Fremont cottonwood (Populus fremonti) is a foundation riparian tree species that drives community structure and ecosystem processes in southwestern U.S. ecosystems. Despite its ecological importance, little is known about the ecological and environmental processes that shape its genetic diversity, structure, and landscape connectivity. Here, we combined molecular analyses of 82 populations including 1312 individual trees dispersed over the species' geographical distribution. We reduced the data set to 40 populations and 743 individuals to eliminate admixture with a sibling species, and...

Climate change is arguably the greatest challenge to conservation of our time. Most vulnerability assessments rely on past and current species distributions to predict future persistence but ignore species’ abilities to disperse through landscapes, which may be particularly important in fragmented habitats and crucial for long-term persistence in changing environments. Landscape genetic approaches explore the interactions between landscape features and gene flow and can clarify how organisms move among suitable habitats, but have suffered from methodological uncertainties. We used a...

Estimating landscape resistance to animal movement is the foundation for connectivity modeling, and resource selection functions based on point data are commonly used to empirically estimate resistance. In this study, we used GPS data points acquired at 5-min intervals from radiocollared pumas in southern California to model context-dependent point selection functions. We used mixed-effects conditional logistic regression models that incorporate a paired used/ available design to examine the sensitivity of point selection functions to the scale of available habitat and to the behavioral...