Treesearch

Climate conditions, such as temperature or precipitation, averaged over several decades strongly affect species distributions, as evidenced by experimental results and a plethora of models demonstrating statistical relations between species occurrences and long-term climate averages. However, long-term averages can conceal climate changes that have occurred in recent decades and may not capture actual species occurrence well because the distributions of species, especially at the edges of their range, are typically dynamic and may respond strongly to short-term climate variability. Our...

This report presents a summary of the most recent inventory information for Nevada’s forest lands. The report includes descriptive highlights and tables of area, number of trees, biomass, volume, growth, mortality, and removals. Most of the tables are organized by forest-type group, species group, diameter class, or ownership. The report also describes inventory design, inventory terminology, and data reliability. Results show that Nevada’s forest land totals 10.6 million acres. Sixty-three percent (6.7 million acres) of this forest land is administered by the Department of Interior’s...

Joshua tree (Yucca brevifolia Engelm.) is a large, arborescent member of the yucca genus. It is an endemic and visually dominant plant in portions of the Mojave Desert, USA. We document the unique and heretofore unreported directional orientation of its flower panicles. The flower panicles grow primarily at the tips of branches that are oriented to the south. When branches with flower panicles are not oriented in a southerly direction, the flower panicles themselves tend to bend or tilt toward the south. This strategy maximizes exposure of the panicles to direct solar radiation, which,...

Presently there is a lack of information describing US southwestern energy consumption and emissions generated from the sawmilling industry. This article uses a mail survey of softwood sawmills in the states of Arizona, Colorado, and New Mexico to develop a profile of on-site energy consumption and selected emissions for the industry. Energy consumption is categorized by fuel type on a production basis for both renewable and nonrenewable sources for production year 2012. Selected emissions from on-site energy consumption were also estimated for respondent sawmills. Survey respondents...

Herbicide use varies both spatially and temporally within managed forests. While information exists on the effects of herbicide use on water quality at the site and small catchment scale, little is known about the cumulative effects of herbicide use at the landscape scale. A cumulative effects analysis was conducted in the upper Rangitaiki catchment (118,345 ha) in New Zealand, to determine the risk to water quality from two herbicides commonly used for post-plant weed control: terbuthylazine and hexazinone. Data from a 12.5 ha catchment study within the Rangitaiki Basin, where these...

The Integrated Rangeland Fire Management Strategy (hereafter Strategy, DOI 2015) outlined the need for coordinated, science-based adaptive management to achieve long-term protection, conservation, and restoration of the sagebrush (Artemisia spp.) ecosystem. A key component of this management approach is the identification of knowledge gaps that limit implementation of effective strategies to meet current management challenges. The tasks and actions identified in the Strategy address several broad topics related to management of the sagebrush ecosystem. This science plan is organized around...

Astragalus utahensis (Torr.) Torr. & A. Gray (Fabaceae) (Utah milkvetch) is native lo the arid Great Basin and has desirable attributes that make it a good candidate for restoration in arid, noncompetitive situations. Seed dormancy is a significant barrier to consistent establishment for this species. Species of Alternaria and Aspergillus fungi have potential to enhance germination of A. utahensis seed; therefore, we conducted trials to investigate Alternaria and Aspergillus effects on germination and emergence under controlled in vitro conditions or in soil in a growth chamber, in a...

Seeds of most Great Basin lupine (Lupinus spp. [Fabaceae]) species are physically dormant and thus, difficult to establish in uniform stands in seed production fields. We designed this study to examine 5 seed scarification techniques, each with 11 levels of application (including a non-scarified control), to reduce the physical seed dormancy of longspur lupine (L. arbustus Douglas ex Lindl.), silvery lupine (L. argenteus Pursh), hairy bigleaf lupine (L. prunophilus M.E. Jones), and silky lupine (L. sericeus Pursh). These 4 perennial Great Basin lupine species are of interest for both...

Bromus tectorum, an inbreeding annual grass, is a dominant invader in sagebrush steppe habitat in North America. It is also common in warm and salt deserts, displaying a larger environmental tolerance than most native species. We tested the hypothesis that a suite of habitat-specific B. tectorum lineages dominates warm desert habitats. We sampled 30 B. tectorum Mojave Desert and desert fringe populations and genotyped 10–26 individuals per population using 69 single nucleotide polymorphic (SNP) markers. We compared these populations to 11 Great Basin steppe and salt desert populations....

Plant-soil feedbacks and interspecific competition are ubiquitous interactions that strongly influence the performance of plants. Yet few studies have examined whether the strength of these interactions corresponds with the abundance of plant species in the field, or whether feedbacks and competition interact in ways that either ameliorate or exacerbate their effects in isolation. We sampled soil from two intermountain grassland communities where we also measured the relative abundance of plant species. In greenhouse experiments, we quantified the direction and magnitude of plant-soil...