Treesearch

Greater sage-grouse Centrocercus urophasianus populations across North America have been declining due to degradation and fragmentation of sagebrush habitat. As part of a study quantifying greater sage-grouse demographics prior to construction of a wind energy facility, we estimated apparent net nest productivity and survival rate of chicks associated with radio-equipped female sage-grouse in Carbon County, Wyoming, USA. We estimated apparent net nest productivity using a weighted mean of the average brood size and used a modified logistic-exposure method to estimate daily chick survival...

Alabama is currently the southern limit of the range of eastern hemlock [Tsuga canadensis (L.) Carriere]. In 2012, several well preserved stumps were excavated from a farm located in Notasulga, Alabama (32 º 33” 6’ N; 85º 40” 22’ W). Even though they were buried in a saturated soil for approximately 1,500 years, the stumps were remarkably well preserved. The low-density wood from one stump was identified as hemlock (Tsuga spp.) due to presence of piceoid, cross-field pitting. We assume the excavated stump was eastern hemlock. Uncorrected carbon dating of one sample was 1580 radiocarbon...

Granivorous rodent populations in deserts are primarily regulated through precipitation-driven resource pulses rather than pulses associated with mast-seeding, a pattern more common in mesic habitats. We studied heteromyid responses to mast-seeding in the desert shrub blackbrush (Coleogyne ramosissima), a regionally dominant species in the Mojave–Great Basin Desert transition zone. In a 5-year study at Arches National Park, Utah, USA, we quantified spatiotemporal variation in seed resources in mast and intermast years in blackbrush-dominated and mixed desert vegetation and measured...

The mean global climate has warmed as a result of the increasing emission of greenhouse gases induced by human activities. This warming is considered the main reason for the increasing number of extreme precipitation events in the US. While much attention has been given to extreme precipitation events occurring over several days, which are usually responsible for severe flooding over a large region, little is known about how extreme precipitation events that cause flash flooding and occur at sub-daily time scales have changed over time. Here we use the observed hourly precipitation from...

Variability in historic fire regimes in eastern North America resulted in an array of oak savannas, woodlands and forests that were dominant vegetation types throughout the region. In the past century, once abundant woodlands have become scarce due to conversion to agriculture, or development of forest structure in the absence of fire. Restoration of oak woodlands is a primary goal for land management agencies and conservation organizations. Although oak woodlands can be restored with a long-term regimen of prescribed burning, a combination of prescribed burning, timber harvesting and...

Although drought is recognized as an important and overarching driver of ecosystem change, its occurrence and effects have been difficult to describe over large geographic areas (Hogg and others 2008, Panu and Sharma 2002).

Eradication is the deliberate elimination of a species from an area. Given that international quarantine measures can never be 100% effective, surveillance for newly arrived populations of nonnative species coupled with their eradication represents an important strategy for excluding potentially damaging insect species. Historically, eradication efforts have not always been successful and have sometimes been met with public opposition. But new developments in our understanding of the dynamics of low-density populations, the availability of highly effective treatment tactics, and bioeconomic...

Bottomland hardwood forests have suffered tremendous losses in the United States. Yet they support some of the densest breeding populations of imperiled migratory song birds in the eastern US, providing nesting habitat for 49 species, 32 of which share some Conservation Status. Traditional management for bottomland hardwood forests in the southeast has tended to rely on one of two strategieslarge scale clearcuts >50 acres, or no-cutting at all. As a conservation organization, Audubon and others have encouraged landowners, land trusts and conservation groups to seek the protection of...

Fire regime characteristics in North America are expected to change over the next several decades as a result of anthropogenic climate change. Although some fire regime characteristics (e.g., area burned and fire season length) are relatively well-studied in the context of a changing climate, fire severity has received less attention. In this study, we used observed data from 1984 to 2012 for the western United States (US) to build a statistical model of fire severity as a function of climate. Wethen applied this model to several (n = 20) climate change projections representing mid-century...