Treesearch

Almost every conservation genetics and evolutionary biology textbook has a section questioning: "What is a species or subspecies?" It has been one of the most discussed, nearly unanswerable questions in all of biology. At issue is how to logically divide a variable that is generally continuous, with some occasional discrete breaks. Answering this question is at times akin to addressing the questions: "How many colors are in a rainbow?” or “Where does red end and orange begin?" School children can tell the two colors apart at the middle part of their defined range, but defining the color of...

Ecologists have a long-term interest in understanding the relative influence of vegetation composition and vegetation structure on avian diversity. LiDAR remote sensing is useful in studying local patterns of avian diversity because it characterizes fine-scale vegetation structure across broad extents. We used LiDAR, aerial and satellite imagery, and avian field data to investigate the relative influence of vegetation structure and canopy composition on avian richness across an aspen-conifer forest gradient. Aspen enhances forest avian biodiversity but has been declining across western...

The Blue Mountains ecoregion (BME) extends from the Ochoco Mountains in central Oregon to Hells Canyon of the Snake River in extreme northeastern Oregon and adjacent Idaho, and then north to the deeply carved canyons and basalt rimrock of southeastern Washington (see fig. 1.1 in chapter 1). The BME consists of a series of mountain ranges occurring in a southwest to northeast orientation, allowing the BME to function ecologically and floristically as a transverse bridge between the Cascade Mountains province to the west, and the main portion of the middle Rocky Mountains province to the east.

1) Bark beetles (Coleoptera: Curculionidae: Scolytinae) can cause extensive tree mortality in forests dominated by their hosts. Among these, the spruce beetle (Dendroctonus rufipennis) is one of the most important beetles in western North America causing Engelmann spruce (Picea engelmannii) tree mortality. 2) Although pheromone traps with attractants are commonly used to monitor spruce beetle populations, the relationship between the numbers of beetles caught in pheromone traps and subsequent tree mortality has not been investigated adequately. 3) We used pheromone traps to catch spruce...

Our results show that loss of perennial herbaceous species, which can result from inappropriate livestock grazing, and loss of shrubs, which often results from fire, interact to affect key functional groups. The implications are that ecosystem resilience to disturbance in Cold Desert shrublands decreases when competition from perennial native grasses and forbs for available resources no longer prevents dominance by A. tridentata and other shrubs and/ or annual invasive grasses. Managing livestock grazing to maintain or increase perennial herbaceous species, especially deep-rooted grasses,...

Climate change effects are already apparent in some Southwestern US forests and are expected to intensify in the coming decades, via direct (temperature, precipitation) and indirect (fire, pests, pathogens) stressors. We grouped Southwestern forests into ten major types to assess their climate exposure by 2070 using two global climate models (GCMs) and two emission scenarios representing wetter or drier conditions and current or lowered emission levels. We estimate future climate exposure over forests covering 370,144 km2 as the location and proportion of each type projected to experience...

Understanding the drivers of ecosystem responses to disturbance is essential for management aimed at maintaining or restoring ecosystem processes and services, especially where invasive species respond strongly to disturbance. In this study, we used repeat vegetation surveys from a network of prescribed fire treatments at the woodland–shrubland interface in the Shoshone Mountains, Nevada, USA, to investigate post-fire responses of the understory plant community. First, we characterized post-fire community trajectories for sites located along an elevational gradient, hypothesizing a...

Spatial modeling is an integral component of most geographic information systems (GISs). However, conventional GIS modeling techniques can require substantial processing time and storage space and have limited statistical and machine learning functionality. To address these limitations, many have parallelized spatial models using multiple coding libraries and have applied those models in a multiprocessor environment. Few, however, have recognized the inefficiencies associated with the underlying spatial modeling framework used to implement such analyses. In this paper, we identify a common...

Snowpack observations in the Intermountain West are sparse and short, making them difficult for use in depicting past variability and extremes. This study presents a reconstruction of April 1 snow water equivalent (SWE) for the period of 1850–1989 using increment cores collected by the U.S. Forest Service, Interior West Forest Inventory and Analysis program (FIA). In the state of Utah, SWE was reconstructed for 38 snow course locations using a combination of standardized tree-ring indices derived from both FIA increment cores and publicly available tree-ring chronologies. These individual...

Fuel treatments in ponderosa pine forests of the northern Rocky Mountains are commonly used to modify fire behavior, but it is unclear how different fuel treatments impact the subsequent production and distribution of aboveground biomass, especially in the long term. This research evaluated aboveground biomass responses 23 years after treatment in two silvicultural installations with different cutting and underburning prescriptions in western Montana. The thinning installation included control (no treatment), thin/no burn, thin/spring burn, and thin/fall burn treatments. The shelterwood...