Treesearch

Introductions of new invasive species continue with ever-expanding global trade, and the increase in invasive species does not show any sign of saturation for most taxonomic groups. However, some non-native species may arrive in an area and fail to become established or have no measurable impact. Thus, the protection of valued ecosystems depends on reliable knowledge about the species that are or might be invading, the ecosystems that are being invaded, the potential magnitude of different types of harm, the availability and effectiveness of management responses, and the desired state of...

Alaska has fewer invasive species and is less impacted by invasive species than most places on Earth. Until recently, Alaska has been protected by its cold climate and by its comparative lack of roads and other development.However, these barriers are eroding. Warming climate trends and longer shoulder seasons have reduced the climate flter that so far may have prevented some invasive species from establishing in the State (Figs. A1.1 and A1.2; Carlson et al. 2015; Jarnevich et al. 2014; Sanderson et al. 2012; Wolken et al. 2011). More extensive wildland fire combined with increasing...

Ongoing revitalization of the >5000-year-old tradition of using trees for vital culture and heritage activities including carving and weaving affirms Alaska Native resilience. However, support for these sustained cultural practices is complicated by environmental and political factors. Carving projects typically require western redcedar (Thuja plicata) or yellow cedar (Callitropsis nootkatensis) trees more than 450 years of age—a tree life stage and growth rate inconsistent with current even-aged forest management strategies. Herein, we qualitatively assess the significance of wood...

The coastal zone of southeast Alaska contains thousands of streams and rivers that drain one of the wettest, carbon‐rich, and most topographically varied regions in North America. Watersheds draining temperate rainforests, peatlands, glaciers, and three large rivers that flow from the drier interior of the Yukon Territory and British Columbia discharge water and dissolved organic carbon (DOC) into southeast Alaskan coastal waters. This area, which we have designated the southeast Alaska drainage basin (SEAKDB), discharges about twice as much water as the Columbia or Yukon Rivers. An...

Variation among demographic rates for a population reflects the allocation of available energy by individuals to competing life-history strategies. Species exhibiting slow-paced life histories often prioritize energy allocation to adult survival over any single reproductive event, therefore maximizing future reproductive potential. Survival of adult female ungulates is generally high with little variability, whereas survival of young is lower and often highly variable. When adult survival is high with low variability, juvenile survival may have a proportionally greater effect on population...

The management of species that occur in low densities is a conservation concern worldwide across taxa with consequences for managers and policymakers. The distribution boundary at the upper extent of fish in North America receives extra attention because stream reaches with fish are managed differently and often have more protections than fishless reaches. Here, we examine the relative reliability of water environmental DNA (eDNA), polymerase chain reaction (PCR)-amplified for Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) to detect the upper extent of fish across streams as a...

The 741 million acres of forestland in the United States play a role in mitigating the effects of climate change by sequestering nearly 16 percent of the atmospheric carbon dioxide emissions produced annually in our country. Reducing the conversion of forestland to other uses and planting even more trees, whether through afforestation or reforestation, would increase the nation’s carbon storage capacity. The U.S. Department of Agriculture (USDA) has several incentive programs to accomplish these goals. Researchers with the USDA Forest Service and Portland State University modeled various...

Forest ecosystems are notably influenced by: 1) the rate and spatial distribution of forest land development, and 2) how remaining undeveloped forest lands are managed. Regarding this second factor, economics and ecology research conducted in different locations in the U.S. suggests that increasing housing development can reduce the profitability of commercial timber production and thus the intensity with which landowners manage their forest lands. Some studies, however, suggest that in some locations these effects are not evident. We sought to consider what contextual factors might...

Pastoralists and researchers (and others) are finding new ways of working together worldwide, attempting to sustain pastoral livelihoods and rangelands in the face of rapid and profound changes driven by globalization, growing consumption, land-use change, and climate change. They are doing this partly because of a greater need to address increasing complex or “wicked” problems, but also because local pastoral voices (and sometimes science) still have little impact on decision-making in the governmental and private sectors. We describe here, using six worldwide cases, how collaborative...

The biodiversity hypothesis posits that declining biodiversity may be responsible, at least in part, for the global increase in immune diseases. However, few studies have been able to demonstrate a link between exposure to biodiversity and specific health outcomes. We test whether exposure to plant diversity protects against childhood acute lymphoblastic leukemia (ALL) by promoting immune maturation. Our sample consisted of all children born in New Zealand from 1998 to 2013 (n = 899,126; 264 ALL cases), which we followed from birth to age five. We calculated plant-diversity metrics using...