Treesearch

Geographical variation in the likelihood of biological invasions can be affected by propagule pressure and habitat suitability, which are driven by ecological and social processes. Past studies have empirically quantified the role of drivers by comparing geographical variation in numbers of invading species with variation in candidate factors; however, lack of data has limited empirical studies for individual species. Lymantria dispar (L.), a nonnative forest pest formerly known as gypsy moth, is an exemplar species for exploring invasion drivers because of extensive records on its spread....

1. Corticosterone is a steroid hormone integral to a variety of physiological pathways and is strongly associated with the vertebrate stress response. In avian species, circulating corticosterone is sequestered into developing feathers and is used as an indicator of energy allocation during feather growth and widely applied in conservation physiology.2. The northern spotted owl Strix occidentalis caurina is a federally threatened old-growth forest obligate of conservation concern endemic to the Pacific Northwest of the United States and Canada. The effects of landscape characteristics and...

Prey respond to predation risk with a range of behavioral tactics that can vary based on space use and hunting mode of the predator. Unlike other predators, human hunters are often more spatially and temporally restricted, which creates a period of short‐duration, high‐intensity predation risk for prey. Consequently, identifying the roles different hunting modes (i.e., archery and rifle), hunts for targeted and non‐targeted species, and landscape features play in altering spatial and temporal responses of prey to predation risk by humans is important for effective management of harvested...

Nonnative tree species have received less scientific attention than nonnative species in general, but when a forest is colonized by a nonnative tree species, the ecological effects can be significant as a change in tree species composition can alter the structural and functional attributes of forest ecosystems. We assess the abundance, geographic distribution, contribution to forest structure (including carbon), and temporal trends of nonnative tree species between the most current inventory and the previous one, ranging from 3 to 15 years earlier, within the conterminous United States...

Wildland fire can cause significant damage but is also a natural process that is key to the healthy functioning of many ecosystems worldwide. Primary fuels for a wildland fire are the dead foliage and small branches which accumulate as litter on the ground. A cone calorimeter was used to measure the various aspects of these fuels. A single sample of preignition gases from the live leaves of seven plant species were vacuum collected on quality filters and within super-chilled solvent mixtures. GC-TOFMS (1D) and GCxGC-TOFMS (2D) were used to characterize the "white" smoke emissions. The...

Soil organic matter (SOM) is the largest terrestrial pool of organic carbon, and potential carbon-climate feedbacks involving SOM decomposition could exacerbate anthropogenic climate change. However, our understanding of the controls on SOM mineralization is still incomplete, and as such, our ability to predict carbon-climate feedbacks is limited. To improve our understanding of controls on SOM decomposition, A and upper B horizon soil samples from 26 National Ecological Observatory Network (NEON) sites spanning the conterminous U.S. were incubated for 52 weeks under conditions representing...

Continuous water level monitoring using absolute pressure transducers with onboard data logging is common practice in hydrologic studies. While there has been some discussion and study of temperature-derived error (TDE), there has not been a systematic evaluation of the problem. We sought to answer three questions: (1) are current best practices enough to avoid these errors, (2) can laboratory correction be used to correct field data from varying conditions, and (3) what is the scale of the additional uncertainty of the correction procedure? We evaluated the magnitude of such errors under...

Understanding the controls on the amount and persistence of soil organic carbon (C) is essential for predicting its sensitivity to global change. The response may depend on whether C is unprotected, isolated within aggregates, or protected from decomposition by mineral associations. Here, we present a global synthesis of the relative influence of environmental factors on soil organic C partitioning among pools, abundance in each pool (mg C g−1 soil), and persistence (as approximated by radiocarbon abundance) in relatively unprotected particulate and protected mineral-bound pools. We show...

Ungulates place immense consumptive pressure on forest vegetation globally, leaving legacies of reduced biodiversity and simplified vegetative structure. However, what remains unresolved is whether browse-induced changes occurring early in succession ultimately manifest themselves in the developed forest canopy. Understanding the development and persistence of these legacies is critical as canopy structure is an important determinant of forest ecosystem functions such as carbon sequestration and wildlife habitat. We measured how white-tailed deer Odocoileus virginianus browse during stand...

Northern spotted owl (Strix occidentalis caurina), a species listed under the Endangered Species Act, have been monitored for nearly three decades using callback surveys and mark-and-recapture methods. Callback surveys can result in negative effects on the owl yet are widely used on federal, state, and private forest land prior to activities that range from timber sales to restoration projects. Despite conservation efforts, spotted owl populations are declining due to habitat loss and invasive barred owls (S. varia); and as barred owl populations increase, spotted owls are becoming harder...