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.

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...
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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...
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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...
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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...
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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...
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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...
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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...
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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...
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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...
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Hurricanes, Humans, and Future Ecosystems (LUQ LTER)
Ecosystems are increasingly subjected to combined natural and human disturbances. Since 1990 in Puerto Rico we have been studying human and hurricane disturbance and their interactions in a tropical forest. The work takes place on the 16-ha Luquillo Forest Dynamics Plot (LFDP) in the Luquillo Mountains. Part of the plot was logged or farmed up until the 1930s (Fig. 1). On the rest of the plot...
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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...
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Clean Water: Minimizing Nitrogen Pollution (KBS LTER)
Through a variety of long-term studies, KBS LTER research has significantly advanced scientific understanding of nitrogen cycling in cropping systems as well as in the broader landscape. Agricultural landscapes commonly have excessive concentrations of nitrate (an especially mobile form of nitrogen) in ground and surface waters due to fertilizer applications in excess of what the crops can use....
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Soil Microbes and Agriculture (KBS LTER)
Microbes in terrestrial environments are important catalysts of global carbon and nitrogen cycles, including the production and consumption of greenhouse gases in soil. Some microbes produce the greenhouse gases carbon dioxide (CO2) and nitrous oxide (N2O) while decomposing organic matter in soil. Others consume methane (CH4) from the atmosphere, thus helping to mitigate climate change. The...
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Diverse Landscapes Curtail Crop Pests (KBS LTER)
The soybean aphid Aphis glycines, an invasive insect pest, is the greatest threat to soybean production in the United States. First detected in the United States in 2000, this East Asian pest has spread rapidly through the Midwest and costs growers about $30 million to $50 million per year in reduced yield. By 2005, farmers had responded with a 20-fold increase in insecticide use, spraying...
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Climate Change (KBS LTER)
Agriculture and Climate Change Since 1992 scientists at the KBS LTER site have studied fluxes of the major, naturally occurring greenhouse gases (GHGs) -- carbon dioxide (CO2), methane, and nitrous oxide -- in the cropped and natural ecosystems of the Main Cropping System Experiment. These data, coupled with concurrent measurements of soil carbon and fuel and agrochemical use, enabled KBS...
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Accessible Ecology (JRN LTER)
Large amounts of information have been collected, and software tools have been developed to understand and predict dynamics of ecological systems. However, much of the data and tools remain inaccessible to a broad audience beyond the initial scientists, data collectors, and software developers. The Jornada has been developing tools and activities designed to make scientific knowledge...
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Heterogeneity and Nonequilibrium Dynamics (JRN LTER)
Much of ecological research in terrestrial systems focuses on detailed understanding of local processes, such as competition for limiting resources, on fine-scale dynamics of individual plots that are extrapolated to broad-scale patterns of ecosystem types and biomes. Although this perspective can explain short-term dynamics at fine scales of plants and patches in drylands, landscape-scale...
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Expanding Deserts (JRN LTER)
Desertification is the shift from perennial grasslands to shrublands that occurs globally to impact nearly 40% of the Earth’s land surface and a fifth of the world’s human population. Desertification results from interactions between human activities (such as livestock overgrazing) and prolonged drought. However, these broad-scale drivers are insufficient to explain variability in dynamics at...
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Tipping Points (JRN LTER)
Tipping points resulting in state changes (or regime shifts) have been documented in many ecosystem types around the world, and are particularly important in dryland ecosystems, including those of the southwestern US. Dryland state changes include the conversion of agriculturally productive grasslands to unproductive shrublands, conversion to dominance by invasive species, or the loss of...
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Shifting Songbirds (HBR LTER)
Forest bird populations of northeastern North America are being increasingly affected by environmental challenges, including habitat loss and degradation, forest disturbances such as ice storms, atmospheric pollutants such as acid deposition, pathogens that enhance tree mortality and climate change. To develop conservation and management plans that might mitigate such impacts, a mechanistic...
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Winter Climate Change (HBR LTER)
While many from cold northern regions might welcome a bit of climate warming, the negative consequences for others -- for example, many arctic populations -- clearly counterbalance the benefits. In the northeastern United States and elsewhere, one of the ironic outcomes of winter climate warming could be an increase in the frequency of soil frost in forests; long-term observations at Hubbard...
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Forests that Govern (HBR LTER)
The northeastern United States has been blessed with beautiful and bountiful forests that provide human society with a variety of valuable ecosystem goods and services including forest products, recreational opportunities, diverse wildlife, stable water flow, pure water quality, and sequestration of carbon. Pioneering research at Hubbard Brook, designed to elaborate ecological theory on the...
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Acid Rain (HBR LTER)
Acid rain results when the combustion of fossil fuels releases sulfur dioxide and nitrogen oxides to the atmosphere. These contaminants are deposited to the Earth’s surface as precipitation, gases or particles and are called acid rain or acidic deposition. Acid rain was "discovered" in North America at Hubbard Brook through measurements of precipitation chemistry that were started in 1963. The...
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Envisioning the Future (HFR LTER)
We are living in times of rapid social and environmental change. Scientists and policy makers urgently require analyses of multiple interacting processes in order to anticipate and adapt to future global change. Understanding future environmental change will require new approaches to synthesizing ecological and social sciences. This is no easy task. The study of coupled human and natural systems...
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Foundation Species Matter (HFR LTER)
We are currently living through the sixth great extinction crisis in the Earth’s history. Ecologists and evolutionary biologists have documented that the unprecedented and rapidly accelerating loss of non-human species is the direct result of human activities: habitat conversion, over-consumption of resources, and worldwide introductions -- both deliberate and accidental -- of pests and pathogens...
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