Skip to main content
Advanced Search

Filters: Tags: Seasonal (X)

11 results (205ms)   

View Results as: JSON ATOM CSV
Past studies of plant?microbe interactions in the alpine nitrogen cycle have revealed a seasonal separation of N use, with plants absorbing N primarily during the summer months and microbes immobilizing N primarily during the autumn months. On the basis of these studies, it has been concluded that competition for N between plants and microbes is minimized along this seasonal gradient. In this study, we examined more deeply the links between microbial population dynamics and plant N availability in an alpine dry meadow. We conducted a year-round ?eld study and per formed experiments on isolated soil microorganisms. Based on previous work in this ecosystem, we hypothesized that microbial biomass would decline before...
Point nesting data, Environmental Sensitivity Index (ESI) importance and nesting areas and sightings per unit effort (SPUE) for the three species of turtles - Green sea turtle, Leatherback turtle, and Loggerhead turtle.
Decomposition of grass leaf litter was studied on a shortgrass prairie using chemicals (HgCl2 and CuSO4) to prevent microbial activity (abiotic treatment), 53??m nylon mesh to exclude mesofauna (microbial treatment), and l?mm nylon mesh to allow the access of mesofauna. After 9 months, 15.2% of the blue grama grass litter was decomposed in the microbial treatment, and 29.4% was decomposed in the microbial plus mesofaunal treatment. After 7 months, 6.2% of the litter had disappeared from the abiotic treatment. There was a general decrease in C:N ratios with the microbial treatment lowest at the end of the experiment. Total available carbohydrates generally decreased with time. Certain mite families fluctuated with...
We examine 20-yr data sets of seismic activity from 10 volcanic areas in the western United States for annual periodic signals (seasonality), focusing on large calderas (Long Valley caldera and Yellowstone) and stratovolcanoes (Cascade Range). We apply several statistical methods to test for seasonality in the seismic catalogs. In 4 of the 10 regions, statistically significant seasonal modulation of seismicity (> 90% probability) occurs, such that there is an increase in the monthly seismicity during a given portion of the year. In five regions, seasonal seismicity is significant in the upper 3 km of the crust. Peak seismicity occurs in the summer and autumn in Mt. St. Helens, Hebgen Lake/Madison Valley, Yellowstone...
thumbnail
In the expectation that global climate will change steadily in the coming decades, this research project had the goal to obtain a more detailed view of the climatic changes that Hawai’i could experience by the mid and late 21st century. Given the importance of rainfall for Hawaiian ecosystems and freshwater reserves, this project investigated past seasonal rainfall pattern and developed a statistical model to estimate future rainfall changes for the major islands. As a result of this research, high-resolution maps and data are now available that researchers can use to study potential impacts on endangered species, or use the rainfall changes as input in decision-support tools.This data product provides data files...
thumbnail
Seasonal changes in soil phosphorus (P) availability are not yet known for many ecosystems. We report seasonal changes in several pools of soil phosphorus, including plant available P from the Mojave Desert and Colorado Plateau. In addition we show that cheatgrass changes soil P fractions in unexpected and ecologically significant ways. Monthly soil samples (0-10 cm) from four sites in Canyonlands National Park in southeast Utah, are analyzed for P with a modified Hedley P fractionation method. Labile P (plant available) peaks in spring and autumn with significant monthly variation. Surprisingly, HCl extractable P changes as well, with a pattern inverse to that of labile P. Each of these sites has considerable Bromus...
Includes: Seasonal data on Zooplankton - biomass data were obtained from the COPEPOD database (NOAA) for 1977-2007, Chlorophyll - measured to determine phytoplankton concentration, Sea Surface Temperature - data were extracted from three dimensional climatologies representing 28 years from 1980 - 2007, averaged, and interpolated with ordinary kriging to produce a smooth surface, and Stratification - data helps describe the physical environment of the water column near the surface. These data help to understand the seasonal patterns of mixing and stratification that help to determine areas of high productivity and benthic-pelagic coupling.
Seasonal trends and weighted persistence for 3 target species: Blueback herring, American shad, and Atlantic mackerel The Trend in Abundance Metric was developed to address the following question concerning the distribution of specific fish species relative to places in the North Atlantic Marine Ecoregion: Where in the ecoregion has the abundance been increasing or decreasing? (trends) The Weighted Persistence metric was developed to address the following questions concerning the distribution of specific fish species relative to places in the North Atlantic Marine Ecoregion: Where in the ecoregion has the species been consistently found over time? (persistence) Where in the ecoregion is the species consistently...
We examine 20-yr data sets of seismic activity from 10 volcanic areas in the western United States for annual periodic signals (seasonality), focusing on large calderas (Long Valley caldera and Yellowstone) and stratovolcanoes (Cascade Range). We apply several statistical methods to test for seasonality in the seismic catalogs. In 4 of the 10 regions, statistically significant seasonal modulation of seismicity (> 90% probability) occurs, such that there is an increase in the monthly seismicity during a given portion of the year. In five regions, seasonal seismicity is significant in the upper 3 km of the crust. Peak seismicity occurs in the summer and autumn in Mt. St. Helens, Hebgen Lake/Madison Valley, Yellowstone...


    map background search result map search result map Cheatgrass (Bromus tectorum L.) and seasonal patterns of soil phosphorus availability in arid ecosystems Datasets for "Climate Change Research in Support of Hawaiian Ecosystem Management: An Integrated Approach" Cheatgrass (Bromus tectorum L.) and seasonal patterns of soil phosphorus availability in arid ecosystems Datasets for "Climate Change Research in Support of Hawaiian Ecosystem Management: An Integrated Approach"