Treesearch

A novel spirocyclic γ-lactam, named spirostaphylotrichin W (1), was isolated together with the well known and closely related spirostaphylotrichins A, C, D, R and V, as well as triticone E, from the liquid cultures of Pyrenophora semeniperda (anamorph: Drechslera), a seed pathogen proposed for cheatgrass (Bromus tectorum) biocontrol. Spirostaphylotrichin W was characterized as (3S*,4S*,5S*,6S*,9Z,10Z)-4,6-dihydroxy-2,3-dimethoxy-3-methyl-10-propyliden-2-azaspiro [4.5]dec-8-ene-1,7-dione, by spectroscopic and chemical methods. The relative stereochemistry of spirostaphylotrichin W was...

The seed pathogen Pyrenophora semeniperda has demonstrated potential as a mycoherbicidal biocontrol for eliminating persistent seed banks of annual bromes on western North American rangelands. This pathogen exhibits variation in virulence that is related to mycelial growth rate, but direct laboratory tests of virulence on seeds often have low repeatability. We developed a rapid and sensitive high pressure liquid chromatography method for quantification of the phytotoxin cytochalasin B in complex mixtures in order to evaluate its use in virulence screening. All 10 strains tested produced...

The convolution of an input with a response function has been widely used in hydrology as a means to solve various problems analytically. Due to the high computation demand in solving the functions using numerical integration, it is often advantageous to use the discrete convolution instead of the integration of the continuous functions. This approach greatly reduces the amount of the computational work; however, it increases the possibility for mass balance errors. In this study, we analyzed the characteristics of the kernel function for the Hayami convolution solution to the linear...

Streams and rivers host a significant portion of Earth's biodiversity and provide important ecosystem services for human populations. Accurate information regarding the status and trends of stream resources is vital for their effective conservation and management. Most statistical techniques applied to data measured on stream networks were developed for terrestrial applications and are not optimized for streams. A new class of spatial statistical model, based on valid covariance structures for stream networks, can be used with many common types of stream data (e.g., water quality attributes...

Ecosystem production functions for water supply, climate regulation, and water purification were estimated for 568 headwater streams and their catchments. Results are reported for nine USA ecoregions. Headwater streams represented 74-80% of total catchment stream length. Water supply per unit catchment area was highest in the Northern Appalachian Mountains ecoregion and lowest in the Northern Plains. C, N, and P sequestered in trees were highest in Northern and Southern Appalachian and Western Mountain catchments, but C, N, and P sequestered in soils were highest in the Upper Midwest...

Climate change in the 21st Century is projected to cause widespread changes in forest ecosystems. Climate-FVS is a modification to the Forest Vegetation Simulator designed to take climate change into account when predicting forest dynamics at decadal to century time scales. Individual tree climate viability scores measure the likelihood that the climate at a given location and at a given point in time is consistent with the climate recorded for species’ contemporary distribution. These viability scores are input into Climate-FVS. A web-based service is available for providing this input...

Fishes of the genus Cottus have long been taxonomically challenging because of morphological similarities among species and their tendency to hybridize, and a number of undescribed species may remain in this genus. We used a combination of genetic and morphological methods to delineate and describe Cottus schitsuumsh, Cedar Sculpin, a new species, from the upper Columbia River basin, Idaho-Montana, USA. Although historically confused with the Shorthead Sculpin (C. confusus), the genetic distance between C. schitsuumsh and C. confusus (4.84-6.29%) suggests these species are distant relatives...

Mountain pine beetle (Dendroctonus ponderosae) (MPB) outbreaks are increasingly prevalent in western North America, causing considerable ecological change in pine (Pinus spp.) forests with important implications for wildlife. We reviewed studies examining wildlife responses to MPB outbreaks and postoutbreak salvage logging to inform forest management and guide future research. Our review included 16 studies describing MPB outbreak relationships with 89 bird species and 6 studies describing relationships with 11 mammalian species, but no studies of reptiles or amphibians. We included...

Sahara Mustard (Brassica tournefortii; hereafter mustard), an exotic plant species, has invaded habitats throughout the arid southwestern United States. Mustard has reached high densities across aeolian sand habitats of southwestern deserts, including five distinct sand habitats in the eastern Coachella Valley, California. We examined trends in ground-dwelling arthropod community structure concurrent with mustard invasion in 90 plots within those habitats from 2003 to 2011 (n = 773 plot_years). We expected arthropod communities to respond negatively to mustard invasion because previous...

Mexican Spotted Owls (Strix occidentalis lucida) are common in older forests within their range but also persist in many areas burned by wildfire and may selectively forage in these areas. One hypothesis explaining this pattern postulates that prey abundance increases in burned areas following wildfire. We observed movement to wintering areas within areas burned by wildfire by four radio-marked Mexican Spotted Owls in the Sacramento Mountains, New Mexico. These movements occurred during the winters of 2004-2005 and 2005-2006, with some owls migrating in both winters and others in only one....