Skip to main content
USGS - science for a changing world
Advanced Search

Filters: Tags: Ecosystems (X) > Date Range: {"choice":"year"} (X)

163 results (20ms)   

Filters
Date Types (for Date Range)
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
thumbnail
Nitrogen (N) is a critical limiting nutrient that regulates plant productivity and the cycling of other essential elements in forests. We measured foliar and soil nutrients in 22 young Douglas-fir stands in the Oregon Coast Range to examine patterns of nutrient availability across a gradient of N-poor to N-rich soils. N in surface mineral soil ranged from 0.15 to 1.05% N, and was positively related to a doubling of foliar N across sites. Foliar N in half of the sites exceeded 1.4% N, which is considered above the threshold of N-limitation in coastal Oregon Douglas-fir. Available nitrate increased five-fold across this gradient, whereas exchangeable magnesium (Mg) and calcium (Ca) in soils declined, suggesting that...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
This review article describes vectors for nitrogen and phosphorus delivery to riparian zones in semiarid African savannas, the processing of nutrients in the riparian zone and the effect of disturbance on these processes. Semiarid savannas exhibit sharp seasonality, complex hillslope hydrology and high spatial heterogeneity, all of which ultimately impact nutrient fluxes between riparian, upland and aquatic environments. Our review shows that strong environmental drivers such as fire and herbivory enhance nitrogen, phosphorus and sediment transport to lower slope positions by shaping vegetative patterns. These vectors differ significantly from other arid and semiarid ecosystems, and from mesic ecosystems where the...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
We investigated the effects on the reservoir food web of a new temperature control device (TCD) on the dam at Shasta Lake, California. We followed a linked modeling approach that used a specialized reservoir water quality model to forecast operation-induced changes in phytoplankton production. A food web–energy transfer model was also applied to propagate predicted changes in phytoplankton up through the food web to the predators and sport fishes of interest. The food web–energy transfer model employed a 10% trophic transfer efficiency through a food web that was mapped using carbon and nitrogen stable isotope analysis. Stable isotope analysis provided an efficient and comprehensive means of estimating the structure...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
A positive relationship between interannual sea level and plant growth is thought to stabilize many coastal landforms responding to accelerating rates of sea level rise. Numerical models of delta growth, tidal channel network evolution, and ecosystem resilience incorporate a hump-shaped relationship between inundation and plant primary production, where vegetation growth increases with sea level up to an optimum water depth or inundation frequency. In contrast, we use decade-long measurements of Spartina alterniflora biomass in seven coastal Virginia (USA) marshes to demonstrate that interannual sea level is rarely a primary determinant of vegetation growth. Although we find tepid support for a hump-shaped relationship...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
Nitrogen (N) was added for 35 days in the form of 15NH4Cl to Kings Creek on Konza Prairie, Kansas. Standing stocks of N in key compartments (that is, nutrients, detritus, organisms) were quantified, and the amount of labeled N entering the compartments was analyzed. These data were used to calculate turnover and flux rates of N cycling through the food web, as well as nutrient transformation rates. Inorganic N pools turned over much more rapidly in the water column of this stream than in pelagic systems where comparable measurements have been made. As with other systems, the mass of ammonium was low but it was the key compartment mediating nutrient flux through the ecosystem, whereas dissolved organic N, the primary...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
Despite the frequent citation of wetlands as effective regulators of water quality, few quantitative estimates exist for their cumulative retention of the annual river loads of nutrients or sediments. Here we report measurements of sediment accretion and associated carbon, nitrogen, and phosphorus accumulation as sedimentation over feldspar marker horizons placed on floodplains of the non-tidal, freshwater Coastal Plain reaches of seven rivers in the Chesapeake Bay watershed, USA. We then scale these accumulation rates to the entire extent of non-tidal floodplain in the Coastal Plain of each river, defined as riparian area extending from the Fall Line to the upper limit of tidal influence, and compare them to annual...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
The US Environmental Protection Agency established the Adirondack Effects Assessment Program (AEAP) to evaluate and monitor the status of biological communities in lakes in the Adirondack region of New York that have been adversely affected by acid deposition. This program includes chemical analysis of 30 lakes, sampled two to three times each summer. Results of trends analysis for lake chemistry and chlorophyll a (chlor a) are presented for 1994 to 2003, and a general comparison is made with recent results of the Adirondack Long-Term Monitoring (ALTM) Program, which included chemical analysis of all but two of these lakes (plus an additional 24 lakes) monthly, year-round for 1992-2004. Increases in pH were found...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
The loss of coastal marshes is a topic of great concern, because these habitats provide tangible ecosystem services and are at risk from sea-level rise and human activities. In recent years, significant effort has gone into understanding and modeling the relationships between the biological and physical factors that contribute to marsh stability. Simulation-based process models suggest that marsh stability is the product of a complex feedback between sediment supply, flooding regime and vegetation response, resulting in elevation gains sufficient to match the combination of relative sea-level rise and losses from erosion. However, there have been few direct, empirical tests of these models, because long-term datasets...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
This dataset contains measures of seasonal mean bird stopover densities and in seasonal mean bird density based on weather surveillance radar data from 20 radar locations in the Northeast U.S. across seven autumn migrations (15 August through 7 November of 2008-2014) [six autumn migrations for the terminal doppler weather radar (15 August through 7 November of 2009-2014)]. Data are present only in radar-sampled areas for each individual radar (see below for description on how these data are filtered). If you are interested in a continuous map of bird stopover densities for the entire region (and outside of these radar coverage areas), refer to layer “Predicted autumn migratory landbird density, 1km, Northeast U.S.”.The...
thumbnail
This dataset was last updated 02/2017. This version includes a new tidal restrictions metric that assesses the effect of undersized culverts and bridges on tidal regime.The previous version (3.1) was updated on 05/2016 by incorporating a revised version of the land cover classification, DSLland Version 3.1, developed by UMass, which included the addition of The Nature Conservancy’s Northeast lakes and ponds classification.This dataset depicts the ecological integrity of locations (represented by 30 m grid cells) throughout the northeastern United States based on environmental conditions existing in approximately 2010. Ecological integrity is defined as the ability of an area (e.g., local site or landscape) to sustain...
thumbnail
Tropical forests contain > 50% of the world’s known species (Heywood 1995), 55% of global forest biomass (Pan et al. 2011), and exchange more carbon (C), water and energy with the atmosphere than any other ecosystem type (e.g., Saugier et al. 2001). Despite their importance, there is more uncertainty associated with predictions of how tropical forests will respond to warming than for any other biome (Randerson et al. 2009). This uncertainty is of global concern due to the large quantity of C cycled by these forests and the high potential for biodiversity loss. Given the importance of tropical forests, decision makers and land managers around the globe need increased predictive capacity regarding how tropical forests...
thumbnail
Advancing our mechanistic understanding of ecosystem responses to climate change is critical to improve ecological theories, develop predictive models to simulate ecosystem processes, and inform sound policies to manage ecosystems and human activities. Manipulation of temperature in the field, or the “ecosystem warming experiment,” has proved to be a powerful tool to understand ecosystem responses to changes in temperature. No comprehensive synthesis has been conducted since the last one more than 10 years ago. A new synthetic analysis is critically needed to advance our understanding of ecosystem responses to warming, to highlight experimental artifacts and appropriate interpretations, and to guide development...
thumbnail
The SRLCC provided funds to the states of Arizona and New Mexico to support development of the states Crucial Habitat Assessment Tools (CHATs) which provide a decision support system to better incorporate wildlife values, sensitive animals and plants, and important ecosystem features into land use decision-making to reduce conflicts and surprises.Several states have released wildlife mapping tools that are the foundation for displaying crucial wildlife and corridor information. The state and regional CHATs are non-regulatory, and give project planners and the general public access to credible scientific data on a broad scale for use in project analysis, siting and planning. This includes large-scale development...
Categories: Data, Project; Types: ArcGIS REST Map Service, ArcGIS Service Definition, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: AZ-01, AZ-02, AZ-03, AZ-04, AZ-05, All tags...
thumbnail
This dataset provides bi-monthly data on seed biomass collected in shallow water habitats across the fresh to saline gradient at coastal sites in Barataria Bay, Louisiana. This project was co-funded by the Gulf Coast Prairie and the Gulf Coastal Plains and Ozarks Landscape Conservation Cooperatives and the South Central Climate Adaptation Science Center. An alternate reference to this product can be found here: https://www.sciencebase.gov/catalog/item/5a78c158e4b00f54eb1e84a6.
thumbnail
Disparate ecological datasets are often organized into databases post hoc and then analyzed and interpreted in ways that may diverge from the purposes of the original data collections. Few studies, however, have attempted to quantify how biases inherent in these data (for example, species richness, replication, climate) affect their suitability for addressing broad scientific questions, especially in under-represented systems (for example, deserts, tropical forests) and wild communities. Here, we quantitatively compare the sensitivity of species first flowering and leafing dates to spring warmth in two phenological databases from the Northern Hemisphere. One—PEP725—has high replication within and across sites, but...
Categories: Publication; Types: Citation; Tags: Ecosystems
Climate change is expected to have different effects in different parts of the world. For this reason, regionally-specific projections of climate and environmental change are important to help those who need to plan how best to adapt. The goal of this project was to use the latest global climate models and state of the science models of vegetation and hydrology, to describe what the latest science says about the Northwest’s future climate, vegetation, and hydrology. Researchers in the project began by evaluating the ability of climate models to simulate observed climate patterns in the Northwest region. The best performing models were ‘downscaled’, that is, remapped onto the finer grids used in models of hydrology...
thumbnail
Recent evidence suggests that atmospheric nitrate (NO3- ) deposition can alter soil carbon (C) storage by directly affecting the activity of lignin-degrading soil fungi. In a laboratory experiment, we studied the direct influence of increasing soil NO 3- concentration on microbial C cycling in three different ecosystems: black oak-white oak (BOWO), sugar maple-red oak (SMRO), and sugar maple-basswood (SMBW). These ecosystems span a broad range of litter biochemistry and recalcitrance; the BOWO ecosystem contains the highest litter lignin content, SMRO had intermediate lignin content, and SMBW leaf litter has the lowest lignin content. We hypothesized that increasing soil solution NO 3- would reduce lignolytic activity...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
The objectives of this study were to identify processes that contribute to resilience of coastal wetlands subject to rising sea levels and to determine whether the relative contribution of these processes varies across different wetland community types. We assessed the resilience of wetlands to sea-level rise along a transitional gradient from tidal freshwater forested wetland (TFFW) to marsh by measuring processes controlling wetland elevation. We found that, over 5 years of measurement, TFFWs were resilient, although some marginally, and oligohaline marshes exhibited robust resilience to sea-level rise. We identified fundamental differences in how resilience is maintained across wetland community types, which...
Categories: Publication; Types: Citation; Tags: Ecosystems
thumbnail
In this proposal we investigate how tree selection at the local scale affects biodiversity and ecosystem services (Obj. 1). We then look regionally to determine the extent to which trees in cities can be used to predict heat-related threats to rural forests (Obj. 2). We will leverage ongoing investigations of heat-related stress and pest outbreaks in urban and rural forests to develop management recommendations for both systems. These ongoing projects provide a knowledge-base, infrastructure (e.g. study sites), equipment (e.g. Li-Cor Photosynthesis System), and outreach opportunities that will extend the impact of this project (see Synergistic and Future Funding section below). We will also convene a working group...
thumbnail
This dataset depicts the ecological integrity of locations (represented by 30 m grid cells) throughout the northeastern United States based on environmental conditions existing in approximately 2010 for aquatic systems.The values for this dataset were extracted from the Index of Ecological Integrity, Region-wide, Version 3.2 for all aquatic systems. Updated 09/2017. The metadata for the original dataset is as follows:This dataset was last updated 02/2017. This version includes a new tidal restrictions metric that assesses the effect of undersized culverts and bridges on tidal regime. The previous version (3.1) was updated on 05/2016 by incorporating a revised version of the land cover classification, DSLland Version...


map background search result map search result map Support to Western States Crucial Habitat Assessment Tools Consequences of Urbanization and Climate Change on Human and Ecosystem Health Aquatic Index of Ecological Integrity, Region-wide, Version 3.2, Northeast U.S. Index of Ecological Integrity, Stratified by Ecosystem, Region-wide, Version 3.2, Northeast U.S. Seed biomass from shallow coastal water areas along a salinity gradient in Barataria Bay, Louisiana (2015) Autumn migratory landbird stopover density radars, Northeast U.S. Seed biomass from shallow coastal water areas along a salinity gradient in Barataria Bay, Louisiana (2015) Support to Western States Crucial Habitat Assessment Tools Autumn migratory landbird stopover density radars, Northeast U.S. Aquatic Index of Ecological Integrity, Region-wide, Version 3.2, Northeast U.S. Index of Ecological Integrity, Stratified by Ecosystem, Region-wide, Version 3.2, Northeast U.S. Consequences of Urbanization and Climate Change on Human and Ecosystem Health