Treesearch

While many insects cannot survive the formation of ice within their bodies, a few species can. On the evolutionary continuum from freeze-intolerant (i.e., freeze-avoidant) to freeze-tolerant insects, intermediates likely exist that can withstand some ice formation, but not enough to be considered fully freeze tolerant. Theory suggests that freeze tolerance should be favored over freeze avoidance among individuals that have low relative fitness before exposure to cold. For phytophagous insects, numerous studies have shown that host (or nutrition) can affect fitness and cold-tolerance...

Bottomland hardwood forests cover approximately 2.9 million acres of the Coastal Plain and Piedmont region of Virginia and North Carolina. As of 2014, 59 percent of bottomland hardwood forests were in the large-diameter stand-size class. Between 2002 and 2014, area of large-diameter sized stands increased, while that of medium- and small-diameter stands decreased, indicating that the resource is maturing. While total volume of live trees remained steady over the period studied (2002–2014), there were increases in volume for some individual species (for example, white oak) and decreases in...

Throughout much of the range of western white pine, Pinus monticola Dougl., timber harvesting, fire exclusion and the presence of Cronartium ribicola J. C. Fisch., the white pine blister rust (WPBR) pathogen, have led to negative population and genetic consequences. To address these interactions, we examined population dynamics and genetic diversity in 10 populations of western white pine in upper montane forests of the Lake Tahoe Basin. We documented negative population trends for three of the 10 populations. These populations exhibited low estimated growth rates (λ), moderate to high...

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...

Many systems are prone to both exotic plant invasion and frequent natural disturbances. Native species richness can buffer the effects of invasion or disturbance when imposed in isolation, but it is largely unknown whether richness provides substantial resistance against invader impact in the face of disturbance. We experimentally examined how disturbance (drought/burning) influenced the impact of three exotic invaders (Centaurea stoebe, Linaria dalmatica, or Potentilla recta) on native abundance across a gradient of species richness, using previously constructed grassland assemblages. We...

Recent evidence from the southeastern United States of high predation rates by coyotes (Canis latrans) on white-tailed deer (Odocoileus virginianus) fawns combined with reports of predation on adult female deer have prompted concern among wildlifemanagers and hunters regarding the effects ondeer populations.We examined survival rates and causes of mortality among 138 radiocollared adult female deer over 7 years at the Savannah River Site (SRS) in South Carolina, USA, 2006–2013. Our model-averaged prediction of annual survival was 0.871 (95% CI¼0.839–0.902) and did not vary among years. The...

Caragana, with distinctive variation in leaf and rachis characters, exhibits three centers of geographic distribution, i.e., Central Asia, the Qinghai-Tibetan Plateau (QTP), and East Asia, corresponding to distinct biomes. Because Caragana species are often ecologically dominant components of the vegetation in these regions, it is regarded as a key taxon for the study of floristic evolution in the dry regions of temperate Asia. Based on an expanded data set of taxa and gene regions from those previously generated, we employed molecular clock and biogeographical analyses to infer the...

Monarch butterflies (Danaus plexippus), other pollinators, and Greater Sage-Grouse (Centrocercus urophasianus) are currently the focus of increased conservation efforts. Federal attention on these fauna is encouraging land managers to develop conservation strategies, often without corresponding financial resources. This could foster a myopic approach when allocating resources and setting restoration priorities, and at best, allow for inefficiencies in the usage of land management resources, or, at worst, pit one species (or suite of species, e.g., pollinators) against another (e.g.,...

The primary goals of a two-day Russian olive symposium held in February 2014 were to disseminate current knowledge and identify data gaps regarding Russian olive biology and ecology, distributions, integrated management, and to ascertain the feasibility and acceptance of a proposed program for classical biological control of Russian olive. The symposium was hosted by the Northern Rockies Invasive Plant Council in conjunction with NRIPC’s 3rd Invasive Species in Natural Areas Conference, held February 10-15, 2014, in Spokane, WA. Funding to support the Russian olive symposium was received...

An online survey was distributed through email lists provided by various stakeholder groups on behalf of the International Consortium for Biological Control of Russian Olive in spring of 2012. A total of 392 respondents replied from 24 U.S. states and 1 Canadian province. Questions posed in the survey were designed to identify and categorize 1) stakeholders by geographic location, profession and professional affiliation; 2) stakeholder perceptions of Russian olive as a problematic and/or beneficial organism; 3) by ecological, economic and geographic scale stakeholders’ perceived benefits...