Among the many research results from LTER sites, some findings stand out as being particularly important to achieve the LTER goal of providing information to conserve, protect, and manage the nation's ecosystems. Short descriptions of key findings at each site emphasize the importance of long-term data in understanding the pace and pattern of ecological change.
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New Pathways (LUQ LTER) Nitrogen is a key resource for plants and animals. Thus there has been much research on what controls nitrogen retention and loss in terrestrial ecosystems. But much uncertainty remains, especially with regard to gaseous nitrogen losses. This is particularly troubling in the context of human modification of the nitrogen cycle, which is dramatically increasing nitrogen pollution, runoff, and the... Read more |
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Tropical Carbon Cycling (LUQ LTER) Tropical forests (Fig. 1) absorb more atmospheric carbon dioxide (CO2) than any other terrestrial biome globally. They also account for about 30% of global net primary production (i.e., carbon uptake) in about 17% of the land area. These ecosystems play a key role in the global carbon cycle, but there is growing concern that global warming could decrease the ability of tropical forests to... Read more |
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Chain Reaction (MCM LTER) MCM scientists are contributing to the recognition that ecosystem responses to climate change are not necessarily gradual or directional, especially in low diversity ecosystems where harsh environmental conditions dominate (Fig. 1). For example, in soil ecosystems in the McMurdo Dry Valleys in Antarctica there are only a few soil nematode species, compared to the hundreds in a temperate soil... Read more |
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Fast Geochemistry (MCM LTER) The ubiquitous dissolution of soils and sediments results in dissolved loads of major ions and nutrients to streams. In most temperate watersheds, the rate of weathering is generally positively correlated to temperature and precipitation. In the cold and dry McMurdo Dry Valleys of Antarctica, dilute glacial melt water generated during 8-10 weeks in the austral summer flows into well-defined... Read more |
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Habitats on Ice (MCM LTER) Cryoconite (cold dust) holes are small ~10 cm diameter, water-filled, cylindrical holes (~10^3 cm) found in the glacier surface. Often, these holes contain algae. While common to glaciers globally, those in the Dry Valleys of Antarctica are covered by ice. Sand patches on the ice surface, blown on to the glacier by wind, melt into the ice. Once below the surface, the sand absorbs energy from the... Read more |
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Organics From Microbes (MCM LTER) The McMurdo Dry Valleys and other desert oases on the coast of East Antarctica are essentially "plant-free" environments. As a result the dissolved organic material (DOM) present in the water of the dry valley lakes and streams is derived only from the breakdown of biomass originally produced by microbes, e.g. algae and bacteria. These microbes grow in the water column of the lakes, such as... Read more |
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Waiting in Winter Darkness (MCM LTER) The permanently ice-covered lakes studied in the MCM can be considered as an oasis for life in this cold desert because they are some of the few habitats on the Antarctic continent that contain year-round liquid water. Strong microbial linkages have been defined in all of thse lakes and point to the tight coupling of carbon and other nutrients and the reliance of the system on phytoplankton... Read more |
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Coral Reef Observing Network (MCR LTER) Coral reefs are complex, biologically diverse and highly valued ecosystems that are under increasing threat from both natural and human-induced disturbances. Timely ecosystem observations about the condition of coral reefs on a range of temporal and spatial scales are essential to assist policy makers and resource managers to address the challenges of their management and conservation, as well as... Read more |
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Diversity Matters (MCR LTER) As the effects of human society on the global environment intensify, notably to elevate atmospheric concentrations of carbon dioxide, coral reefs and reef-forming corals find themselves the colloquial "canary in the coal mine" in providing early warning of the dire effects of these changes. Nearly 30 years ago, scientists raised the alarm over the effects of unseasonably warm seawater in causing... Read more |
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Fish Grow Coral (MCR LTER) There is an obvious relationship between coral and the tropical fishes that live in close association with them -- in general the more coral there is on a reef, the more fish will occur there. While it is clear that the amount of coral habitat on a reef influences the number of fishes present, MCR scientists have found that the reverse often is true as well -- the number of coral-dwelling fishes... Read more |
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Managing For Resilient Coral Reefs (MCR LTER) Tropical reefs around the world are being disturbed more and more often by events that greatly reduce the amount of living coral on reefs. In some cases the disturbed reef returns to its previous state of high coral cover; however, in other instances, the reef becomes dominated by persistent stands of macroalgae that greatly slow or prevent the re-establishment of coral. Macroalgae can overgrow a... Read more |
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Carbon Storage (NTL LTER) Scientists studying the global carbon cycle have primarily focused on quantifying storage and fluxes of the ocean and the terrestrial landscape, often to the exclusion of wetlands, lakes, rivers, and reservoirs. One of the first hints that aquatic systems may play a larger than expected role in regional and global-scale carbon dynamics was the observation of CO2 supersaturation in a world-wide... Read more |
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Lakes In The Landscape (NTL LTER) NTL researchers developed the concept of "lake landscape position" -- how a lake's location within the larger landscape provides a basis for understanding lake characteristics and dynamics. Lakes can receive water from precipitation, surface runoff (streams and rivers) and groundwater. In general, lakes higher in the landscape (i.e., at greater elevations) receive a larger percentage of their... Read more |
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Managing Water Quality in a Changing World (NTL LTER) Eutrophication, the over-enrichment of lakes and rivers with nutrients, causes toxic algae blooms, deoxygenation, foul odors, fish kills, and heavy economic losses to communities that depend on clean water for drinking, industrial use, or recreation. The fix-up sounds simple: stop adding nutrients to the water. However, lakes and rivers are embedded in complex systems of people and nature,... Read more |
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Real World Solutions (NTL LTER) Some of the most pressing ecological issues are global in nature. Highly valued ecosystem services, such as those provided by lakes and reservoirs, will come increasingly under stress in the future. Studying lake ecosystems at the continental, or even global scale requires a broadly distributed network of sites that can leverage local knowledge, data, and expertise toward the goal of... Read more |
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Science, Scenarios and Surprise (NTL LTER) Ecological forecasting and long-term ecological research are synergistic. Long-term data are essential for calibrating models, and forecasts are hypotheses to be tested by long-term research. Existing models are limited in scope. Generally they provide predictions of biological, biogeochemical or physical trajectories of ecosystems, given specified inputs including human actions.... Read more |
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Tracking Ice Cover (NTL LTER) The annual timing of the formation and disappearance of ice in aquatic systems represents a valuable proxy for climate change and provides an early warning for potential responses that may occur within these ecosystems. The strength as a climate proxy includes the broad spatial distribution and regional, continental, and global abundance of sites, the annual resolution of the data, data records... Read more |
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Air Pollution (NWT LTER) Alpine environments are sensitive indicators of air pollution. By combining monitoring of high-elevation ecosystems and field experiments, NWT scientists have determined that current levels of nitrogen pollution associated with industry and agriculture are altering alpine plant diversity and are polluting lakes and streams, and may soon acidify soils. Long-term ecological measurements and... Read more |
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Early Warning Signs (NWT LTER) NWT research indicates that alpine ecosystems provide important early warning signs of global climate change. Alpine plants and animals survive on the razor's edge of environmental tolerances, making them more sensitive to changes in climate than downstream ecosystems. Signs of stress in the American pika: The hamster-sized American pika or "rock rabbit" is an icon of rocky landscapes that... Read more |
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Water Towers (NWT LTER) Scientists at NWT have documented how high-elevation mountain ecosystems serve as "water towers" to store seasonal snow until it is released later in the year during snowmelt runoff. Every year this melting snow provides large quantities of high quality water that drives the economy and the ecology of the western United States. Much of our research at NWT LTER is related to how changes in... Read more |
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Changes in Ice and Heat (PAL LTER) Changes in sea ice reflect changes in atmospheric and ocean circulation and properties, while the changing seasonality of sea ice plays a predominant role in controlling much of the polar marine ecosystem. Since the late 1970s satellites have allowed us to track sea ice changes from space. For example, using long term satellite data we can determine the length of the ice season by tracking... Read more |
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Delicate Conditions (PAL LTER) The PAL study region along the western Antarctic Peninsula is one of the most rapidly warming places on the planet (see bullet 2), and the ecosystem is responding to the rapid climate warming. PAL observations of the Antarctic marine foodweb started in 1990, but some changes are just now becoming apparent. Antarctic foodchains are traditionally believed to be short and simple, efficiently... Read more |
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New View (PAL LTER) The observed changes in polar ecosystems require the research community to develop the capacity to resolve changes and understand their global implications. Traditional modes of sampling will not suffice and efforts must be focused on developing networks capable of operating in a harsh environment and maintaining themselves for sustained periods at sea. Realizing this, PAL scientists have... Read more |
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Penguins And Climate Change (PAL LTER) The phrase "canaries in the coal mine" has long been understood to reference an environmental early warning system, alluding to the observation that changes in the behavior or even death of caged canaries could reliably alert working miners to the possible presence of lethal underground gases. Long-term ecological research in the Western Antarctic Peninsula (WAP) has revealed an analogous... Read more |
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Modeling Microbial Chemistry (PIE LTER) Scientists understand quite well how chemicals react to produce new compounds, such as when oxygen mixes with natural gas and burns to produce carbon dioxide plus water, but as soon as biology is added to the chemical milieu, the task of predicting what chemical reactions will occur and how quickly remains a great challenge. Primitive organisms, such as bacteria and other microscope life, are at... Read more |
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