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Arctic soils have large stores of carbon and as the arctic environment warms, this carbon may be released to the atmosphere in the form of greenhouse gases such as carbon dioxide and methane. The current understanding of tundra ecosystems and their responses to climate change is based on the idea that nitrogen limits plant growth, however nitrogen availability is strongly seasonal, with large amounts available early in the growing season but very little available later on.

Since nutrient cycling on the tundra changes throughout the season, the research team worked to understand how seasonal changes in tundra plants and soil dynamics are affected by changes in the timing of snowmelt and warming. By experimentally manipulating factors such as the timing of spring thaw and fall freeze directly on the tundra, the team could study how this affects the ecosystem directly. The team was engaged in a mixture of outdoor field sampling, experimentation, and laboratory work. Through this research, the team aimed to better predict the impacts of changing growing season timing and duration on the carbon balance of arctic ecosystems.

While arctic species are all well adapted to living in extreme environments, it is unclear whether different species will respond similarly or differently to the environmental shifts that accompany climate change (e.g. longer growing seasons and warmer temperatures). Stronger responses by some species within a community, or strong responses by certain species groups, could lead to changes in the structure of the food web and its role in arctic ecosystems.

For example, In the Alaskan Arctic, wolf spiders are the largest and most abundant invertebrate predators. A shift in their ecological role could therefore have an important impact on the entire food web. Evidence from Arctic Greenland shows that wolf spider body sizes are becoming larger in response to longer growing seasons. These increases in body size will likely lead to larger spider populations, which could imply an increase in predation on the rest of the community.

This project explored the role of wolf spiders within arctic communities and specifically, whether climate change is stimulating changes in these predators that could influence the structure and functions of arctic food webs. The research team used a variety of methods to examine the impact of wolf spiders, including sampling spiders from various locations around Toolik Lake and carrying out a manipulative experiment that looked at the entire food web.

The research team evaluated how changes in water and nutrient cycles on land can affect stream networks in the Arctic. Changing climate in the Arctic may contribute to increases in the transport of nutrients to river networks and oceans by causing the release of nutrients from thawing permafrost, altering precipitation patterns, increasing rates of biogeochemical reactions, or expanding storage capacity in thawed soils. These changes may have far-reaching effects because flowing water connects land to downstream aquatic ecosystems.

Since the flowpaths connecting terrestrial ecosystems to stream networks remain poorly understood, the group focused on transport and reaction of water and solutes within water tracks, which are linear regions of surface and subsurface flow that connect hillslopes to streams and account for up to 35% of watershed area in arctic tundra. The research increased our understanding of the role of hillslopes in connecting terrestrial ecosystems to stream networks.

The team excavated portions of the Raven Bluff archaeological site, the remains of a prehistoric camp that date to the very end of the last ice age, about 10,000 years ago. The site in Northwestern Alaska is important because it contains the oldest well-preserved collection of archaeological animal bone in the American Arctic. The goal of this research was to gather information at the site that can teach us about what the people who occupied the Raven Bluff site ate; how they obtained, processed and stored their food; and how they manufactured their tools, clothing, and housing.

The site also contains fluted projectile points – a type of stone spear tip that is associated with many of the earliest archaeological sites in the continental United States. Fluted projectile points have been found throughout the Americas, but have never been reliably dated in Alaska. Because people migrated from north-to-south after entering the Americas from Asia across the Bering Land Bridge, fluted points in the far north are expected to be older than the fluted projectile points found in the continental United States. However, initial findings from Raven Bluff indicate that the fluted projectile points at this site are actually younger than the oldest fluted projectile points in the continental United States. By dating these artifacts, the research team is studying the nature and timing of early human population movements in the Americas.

In addition to providing information on early human settlement patterns, the animal remains from this site may shed light on the long term history of caribou populations in what is now the home of the western arctic caribou herd, a resource of critical importance to local residents and a key issue of concern for biologists and wildlife managers.

The research team worked out of Barrow, Alaska at the juxtaposition of two Arctic seas; the Chukchi and Beaufort Seas. It is a region frequently traveled by the endangered bowhead whale. This project had its genesis in understanding why the region near Barrow, Alaska is a feeding hotspot for migrating bowhead whales. The whales and their prey will continue to be a focus of the team's interpretations. The research team conducted oceanographic sampling of the physical and biological marine environment in the region over the period 2005-2011 and observed significant inter-annual variability. Long-term studies of the ocean conditions in the Arctic are needed in order to understand how these environments vary inter-annually. The research team will continue to document conditions in the biological-physical ocean ecosystem, through annual boat-based surveys, in order to predict and understand the potential impacts of climate change on the Arctic ecosystem.

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Titulo financiado: Observación anual del medio ambiente marino biológico y físico en los mares Chukchi y Beauford en las cercanías de Barrow, AK.

El equipo de investigación viajará por avión a Barrow, una comunidad pequeña de aproximadamente 4,500 habitantes en la costa norte de Alaska. Como permitan las condiciones del tiempo, el equipo se embarcara para la colección de muestras oceanográficas a bordo del buque de investigación Annika Marie de 43 pies. Las actividades de a bordo incluirán colección de agua y plancton y mediciones de conductividad, temperatura, y profundidad. A bordo también tomarán nota sobre las ocurrencias de mamíferos marinos y realizarán el procesamiento preliminar de muestras. Si el clima es malo para navegar en el océano ellos pasarán el tiempo en Barrow catalogando muestras y organizándose para los días que pasaran sobre el agua.

Underlying the northern arctic coast of Alaska is a thick layer of permafrost. As water melts and pools on top of the permafrost, thaw lakes are formed. Much of the North Slope of Alaska is covered in such thaw lakes. As they decompose organic material, the bacteria and other microorganisms living in thaw lakes produce either carbon dioxide or methane, depending on the conditions. Methane is a highly potent greenhouse gas with a global warming potential 22 times that of carbon dioxide, and increased microbial activity in thawing permafrost areas could lead to changes in the atmosphere due to the increased release of methane. This research was important to better understand the factors controlling competing microbial processes in carbon-rich tundra soils and how microbial activities interact with biogeochemical cycles (the way specific chemicals move through living and non-living processes on Earth). This information was used to help understand the impacts that changes in climate have on tundra soils.

To collect their data, the research team combined research methods from biology, ecology, and biotechnology. In 2012, the team performed experiments to determine the role that bacterial processes play in the production of carbon dioxide, methane, and other gases from peat soils. They collected data in the field including gas flux measurements, soil cores, thaw depth, water table depth, pH, and dissolved oxygen content. Additionally, they monitored bacterial respiration and conducted related lab experiments.

The Polaris Project is an innovative international collaboration among students, teachers, and scientists. Funded by the National Science Foundation since 2008, the Polaris Project trains future leaders in arctic research and informs the public about the Arctic and global climate change. During the annual month-long field expedition to the Siberian Arctic, undergraduate students conduct cutting-edge investigations that advance scientific understanding of the changing Arctic. During the Polaris Project field course, students and faculty work together to study the Arctic as a system. Instead of focusing on a single question in a single ecosystem type, the group considers a range of questions across multiple components of the Arctic System including forests, tundra, lakes, rivers, estuaries, and the coastal Arctic Ocean. The unifying scientific theme is the transport and transformations of carbon and nutrients as they move with water from terrestrial uplands to the Arctic Ocean. They emphasize the linkages among the different ecosystems, and how processes occurring in one component influence the others.