Antarctic seabirds, including Adélie penguins (Pygoscelis adeliae), south polar skuas (Catharacta maccormicki) and southern giant petrels (Macronectes gigantus), are high trophic level predators that accumulate persistent organic pollutants (POPs) present in the marine food webs in which they forage. Diet and migration patterns influence the level of POP residues per species. Here we examine POP levels within the three bird species based on migratory patterns and trophic level using stable isotope analysis of δ15N and δ13C.

Human land use has dramatically increased coastal watershed nitrogen exports contributing to eutrophication. Improved knowledge of sources and transformations of nitrogen in agricultural and urbanizing watersheds will be critical in developing effective coastal catchment restoration strategies. We investigated effects of land use, hydrologic conditions, and aging infrastructure on nitrogen sources and transformations in forest, agricultural, and urbanizing catchments at the Baltimore Ecosystem Study LTER site.

The temperate forests of eastern North America support high biodiversity and critical ecosystem functions while providing natural resources and cultural benefits to an expanding human population. The region is shaped by a legacy of landscape change: major shifts in climate, vegetation and disturbance at millennial time scales; extensive deforestation for agriculture in the 17th – 19th centuries; and abandonment of farmlands, natural reforestation and increasing urbanization through the mid-21st century.

The objective of this work was to compare estimates of microbial and biogeochemical processes obtained from year round versus field season only data. We also aimed to capture the response of soils to simultaneous warming and nitrogen fertilization in both winter and summer months. Our research took place at the chronic Soil Warming and Nitrogen Fertilization experiment at the Harvard Forest Long Term Ecological Research site. The experiment includes four treatments in a completely randomized design: control, +heat, +N, and +heat +N.

The KBS LTER site is in a diverse, rural-to-semirural landscape typical of the U.S. Great Lakes and upper Midwest regions. Research at KBS asks how diverse plants, animals, and microbes in agricultural landscapes can contribute to farm productivity, environmental performance, and profitability. We study annual and perennial crops including corn, soybean, and wheat rotations, forage crops such as alfalfa, and biofuel crops such as poplars, switchgrass, and native successional communities.

The PAL study area encompasses a 200 x 500 km region extending from the nearshore coastal zone heavily influenced by seasonal sea ice cover to the open Southern Ocean, and from a northern area where sea ice cover is now limited to only the colder winters, to the south where perennial sea ice cover persists into summer months. In this region, primary production is dominated by unicellular phytoplankton and limited by light availability to the October-April period. The region is characterized by spring phytoplankton blooms that have declined by up to 90% in the northern region since 1978.

Although temperate forests have long been thought to be primarily nitrogen limited, resource optimization theory suggests that ecosystem productivity should be co-limited by multiple nutrients. In northeastern North America, air pollution and forest harvesting disturbance elevate N availability and contribute to the likelihood of P limitation.

Tropical environments are changing fast due to deforestation and regrowth, urbanization, climate change, and other forces. The consequences are immense for the whole array of ecosystem services people require. The Luquillo Long-Term Ecological Research Program (LUQ) is tackling these issues in Puerto Rico. LUQ began in 1988 and focused on natural disturbances (hurricanes, landslides, droughts, floods) and ecosystem response. That work revealed patterns of resistance and resilience to cycles of natural disturbance.

Urban landscapes contain a mix of land-use types with different patterns of carbon (C) and nitrogen (N) cycling and export. These patterns affect interactions between ecosystems and the atmosphere.  We have measured soil:atmosphere fluxes of carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) in four urban grassland and eight forested long-term study plots in the Baltimore, MD USA metropolitan area monthly since 1998.

Stabilization of organic matter on mineral surfaces strongly affects rates of soil organic matter (SOM) accumulation and turnover. Controls over SOM are of particular interest in arid and semi-arid systems where the abundance of woody plants has increased globally over the past century. This proliferation of woody plants may lead to significant soil organic carbon (SOC) accumulation, although a large degree of uncertainty exists in the direction and magnitude of SOC pool responses to woody encroachment.