LTER Key Research Findings

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.

Islands of Green (BES LTER)
Urban ecosystems offer fundamentally new habitat for both animal and plant species. While originally viewed as largely disturbed environments, urban places are emerging not as ecological disasters, but rich environments where humans interact strongly with organisms, generating new habitat and assembling new ecological communities. In Baltimore, green space is now known to harbor many species...
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River Corridors (BES LTER)
Riparian (streamside) zones are critical transition zones in the landscape, situated in between upland and aquatic ecosystems. There is a complex web of interactions between riparian zones and surrounding ecosystems that have an important influence on the movement of water and nutrients across the landscape and on biodiversity. Many nutrients are transported from upland ecosystems, especially...
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Urban Watersheds (BES LTER)
A watershed is the area of land where all of the water that is under it or drains off of it goes into the same place. The watershed approach, where the quantity and quality of water leaving a watershed is sampled is like urinalysis, where doctors monitor chemicals in the urine to assess a patient's health. The watershed approach has been applied very successfully in many LTER sites to understand...
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Science and Policy (AND LTER)
A partnership between research and management at the H.J. Andrews Experimental Forest LTER has helped transform forest management and policy in the Pacific Northwest and the U.S.A. (Luoma 2006, Steel et al. 2004). This partnership has spawned new practices and policies for ecosystem management, conservation of old-growth forests, protection of forest streams, and management of dead wood in...
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Temperature Patterns in Mountain Ecosystems (AND LTER)
The basic mechanisms for how temperatures change with elevation in mountain landscapes and how temperature inversions form in valleys have been understood for many years. Under "normal" circumstances, temperatures decrease at a known rate, the "lapse rate", with elevation. Knowledge of the lapse rate allows meteorologists and scientists to extrapolate from a few measurement locations across a...
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The Ecosystem Value of Dead Wood (AND LTER)
Traditionally dead wood has been considered a wasted resource and a hazard in forested landscapes that needed to be eliminated. This all changed starting in the 1970s when Andrews scientists began to examine the many roles dead wood played in forests and streams. This included a wide range of ecological and geomorphic functions including as a habitat and food source for many terrestrial and...
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River Continuum (AND LTER)
The River Continuum Concept (Vannote et al. 1980) has become the dominant concept of how stream ecosystems vary from headwaters downstream to large rivers. The Andrews Forest was one of four primary sites contributing to this pioneering ecosystem paradigm in the late 1970s and early 1980s. The basic idea is that aquatic communities and ecological processes of the stream ecosystem change...
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Old Growth (AND LTER)
Scientific, social, and economic perspectives on old-growth forests and our treatment of them have changed dramatically over the last 150 years in the Pacific Northwest. Research at the H.J.A. Andrews LTER has been central to many those changes in the last 30 years, when perceptions about old-growth shifted from an unproductive forest to be eliminated through exploitation to a valued ecosystem to...
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Arctic Warming (ARC LTER)
Research at the Arctic LTER site is transforming scientific understanding of how the arctic landscape will respond to climate change. Warming of the Arctic is thawing previously frozen ground (permafrost) and in some places, especially where there is buried ice, the thawed soil forms sinks and slumps called thermokarst terrain. In extreme cases this thermokarst terrain leads to complete...
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Cascade Effect (ARC LTER)
The experimental addition of low levels of phosphorus (P) to an arctic stream created a gradual transformation of the tundra stream ecosystem from a cobble-bottom stream covered with diatom-dominated biofilm to a moss-dominated bottom that hosted a different community composition of invertebrates. This transformation was not predicted and was a surprise because for the first seven or eight years...
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Food Sources (ARC LTER)
Arctic Alaska contains hundreds of thousands of lakes, almost all quite shallow. Research at the Arctic LTER on shallow lakes demonstrates that the food webs leading to fish are based mostly on primary production by bottom-dwelling algae rather than on plankton food webs. Yet, arctic fishery biologists continue to emphasize planktonic food webs and recent reviews of climate change in arctic...
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Tracer Techniques (ARC LTER)
A tracer approach to investigation of the nitrogen (N) cycle of streams, first developed at the Arctic LTER, has transformed scientific understanding of the nitrogen cycle and food web structure in flowing waters. By adding a continuous drip of 15N-NH4 (ammonium) or 15N–NO3 (nitrate) to a stream and then sampling the downstream transport, uptake and recycling of nitrogen over distance and...
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Regional Shoreline Change (VCR LTER)
Barrier islands on the U.S. mid-Atlantic coast are characterized by dynamic patterns of shoreline movement. Erosion and accretion driven by episodic storm events, gradual sea-level rise, and natural or engineered changes in sediment supply occur at a variety of temporal and spatial scales, with significant implications for coastal management. VCR researchers were among the first to show that...
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The Power of Invasives (HFR LTER)
Harvard Forest researchers have transformed the scientific understanding of biological invasion by discovering that non-native plants can disrupt the longstanding ecological relationship between native tree seedlings and their beneficial fungi by releasing chemicals belowground. With native plants suppressed, the exotic plants are able to invade forests more aggressively. The impacts of...
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Process Discovered (ARC LTER)
In the early 1990s researchers at the Arctic LTER discovered the answer to a long-standing question of why the recently measured and modeled rates of net ecosystem productivity on land were so much higher than the rates of carbon accumulation integrated over time as found in soil and peat cores. The researchers discovered that carbon dioxide and methane dissolved in groundwater in very high...
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Linked Cycles (ARC LTER)
Our understanding of tundra biogeochemistry has been transformed by long term research by the ARC LTER showing that the carbon and nitrogen cycles are strongly linked and interactive at all steps in the cycle of organic matter. Changes in the arctic carbon cycle in response to climate change cannot be understood or predicted without considering carbon-nutrient interactions. The basis for the...
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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...
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Climate And Disease (SEV LTER)
In the spring of 1993, a flu-like disease appeared in young healthy adults in the Four Corners region of the southwestern United States, with an early mortality rate of 70%. The U.S. Centers for Disease Control identified the cause as a previously-unknown hantavirus, a group of viruses carried by rodents and known to infect humans in Asia and Europe, but not previously identified in North America...
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Watching from Space (SBC LTER)
The relatively recent emergence of satellites to characterize the earth's surface has led to significant advances in the environmental sciences that affect our everyday life (witness, for example, Google Earth). The large spatial coverage obtained from satellites and aircraft enable regional and global comparisons at time [Ed’s note: don’t you mean geographic?] scales that would be near...
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Tipping Points (PIE LTER)
PIE scientists have documented that salt marsh primary production responds to sea level anomalies at several locations along the east coast of the United States. At Plum Island, salt marsh primary production is nearly twice as great during high sea level years as opposed to low sea level years (Fig. 1). Many marshes are perched high in the tidal frame at an elevation that is super-optimal for the...
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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...
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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...
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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...
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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...
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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...
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