Treesearch

Freshwater catchments can experience nutrient deficits that result in reduced primary and secondary productivity. The most commonly limiting nutrients are nitrogen and phosphorus, either separately or together. This review considers the impact of increasing nutrient limitation in temperate basin stream and river systems, focusing on upland areas that currently or previously supported wild Atlantic salmon (Salmo salar) populations.Anthropogenic changes to land use and increases in river barriers have altered upland nutrient dynamics, with particular impacts on salmon and other migratory...

The New York metropolitan area has well over 500 woody plant species growing without cultivation in its wild flora, and the species composition and distributions of these species are changing. For example, numerous native species that were once common are today exceedingly rare. Conversely, many introduced, nonnative species are becoming increasingly common. A new manual was deemed necessary to document these and other changes in the New York Metropolitan Region, which encompasses 25 counties within a radius of 80.5 km of New York, NY. We used records developed by the New York Metropolitan...

Post-fire seeding has been widely implemented in the semiarid Great Basin because natural vegetation recovery may be compromised. Non-native species are often seeded to rapidly establish perennial cover and compete with invasive annuals. We asked whether seeding treatments with different amounts of native and non-native species followed different successional trajectories and whether they became more similar to reference communities over time. We considered restoration implications of seed mix choices and reference community options involving: (a) local unburned vegetation; and (b)...

The overall goal of this project was to improve the representation of combustion processes in coupled fire-atmosphere models operating at the landscape level. Models intended to be used for landscape-scale fires (hundreds of meters to 10s of kilometers), typically divide the simulation domain up into a mesh of grid cells and these grid cells typically range in size from 1-30 meters on a side. As the processes governing combustion occur on considerably smaller scales, models require a means of describing these processes capable of dealing with heterogeneity within a cell and must also be...

The role of regional species diversity in large-scale species ii,vasions h::s bee,, lai-gely controversial. Onthe c,ne hand, it has been proposed thrlt diversity may facilitate invasion ' "diversity begets diversity")because regions with hi~her di •.'ersity may indicate favorable conditions for many more species. On theother hand, high diversity may indicate high levels of niche occupation, thus making it more difficult fornew species to invade. In the )ast, invasion biologists have evaluated how regional native and exoticrichness are related. Here, we test whether the range si,e of exotic...

Numerous wetland depressions occur across the U.S. Atlantic Coastal Plain, a region of complex physiography spanning a landward-to-seaward elevation gradient. Coastal Plain depressional wetlands are noted for supporting a diversity of plant communities that provide important faunal habitats. Because these "isolated" wetlands are vulnerable to degradation and loss on private lands, protected and managed public lands have become important refugia for their conservation. A practical system of vegetation types and vegetation-dynamics models can aid in developing management or restoration...

Climate change, the rising air temperature and changes in the intensity and frequency of rainfall, and sea level rise (SLR), represents one of the most important threats to coastal wetlands that have numerous ecosystem services from erosion and water quality control to wildlife habitat. Climate change-induced disturbances affect the sustainability of coastal wetland ecosystems mainly through altering their hydrologic functions. However, how to assess wetland hydrological resilience, the ability of wetland hydrology to recover from climate disturbances remain challenging. This chapter first...

Prescribed burns and understory thinnings are forest management practices aimed at reducing fuel loads tolessen wildfire threat in the Southern Appalachians, USA. Spiders play a critical role in forest ecosystems bycontrolling insect populations and providing an important food source for vertebrates. We used pitfall andcolored pan traps to investigate how abundance, species richness, and diversity of spiders differed among threefuel reduction treatments administered repeatedly over a 15-year period and untreated controls. Additionally, weexamined how spiders responded to one round (before...