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.

Old Forests Store Carbon (HFR LTER)
Terrestrial ecosystems, especially mid-latitude forests, are accumulating carbon (2.6 Pg-C y-1) that would otherwise contribute to increasing atmospheric CO2. CO2 fertilization, forest regrowth, climate variability, and increased nutrient inputs are potential factors. Ecological theory suggests that forests older than about a century should approach equilibrium and no longer be significant carbon...
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To Be or Not to Be (GCE LTER)
Why are there more organisms in some parts of the landscape than others? Are there genetic differences between populations living in one area as opposed to another? Is it because adults do better in some areas than others? Or, in marine systems, is it because there are more larvae settling from the plankton in one place than another? In the GCE-LTER study site on the Georgia coast,...
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Microbes and Nitrogen (GCE LTER)
Modern molecular techniques have vastly increased our ability to catalogue molecular diversity, but do not reveal how this diversity affects ecological processes. GCE-LTER researchers (in collaboration with researchers funded by the NSF-funded Sapelo Island Microbial Observatory and the Moore Foundation) have combined state of the art molecular methods with ecological studies to explore both...
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Nitrogen to the Coast (GCE LTER)
The export of excess nitrogen input from rivers has been identified as one of the most significant problems facing coastal ecosystems, resulting in eutrophication and adverse environmental effects such as hypoxia and harmful algal blooms. Researchers at the GCE LTER constructed nitrogen budgets for the watersheds of all the major rivers in the southeast to determine the total input of nitrogen as...
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Salt Marsh Herbivores (GCE LTER)
It is obvious to the most casual observer that natural communities are different in different parts of the world. Early naturalists from Europe, for example, marveled at the diversity of life that they found on trips to the tropics. Ever since, scientists have wondered how ecological processes might vary geographically. Early workers suggested that interactions between species might be more...
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Communication to Policymakers (FCE LTER)
The Everglades is imbedded in a human-dominated landscape that is constantly changing in response to local and global environmental manipulations. Working with an inter-governmental task force, FCE has helped create a reporting system linking the causes and consequences of these dynamics and communicating the results in a transparent format accessible to a wide audience. This reporting system has...
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Productivity Gradients in Mangroves (FCE LTER)
Mangrove forests in the Florida Everglades form an ecotone, which is a critical link between freshwater marshes and the marine environments of Florida Bay and the Gulf of Mexico. These forested wetlands provide shoreline protection against storms, "nurseries" for shrimp, fish, and crabs, as well as habitat for several endangered and threatened species such as the American crocodile. FCE...
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Productivity Paradox (FCE LTER)
FCE researchers have found that productivity in the Everglades, and other limestone-based Carbbean wetlands, is dominated by extraordinarily productive algal mats, despite extreme nutrient limitation. This phenomenon has been called a "productivity paradox" (Gaiser et al. 2011). This production would be expected to support a large biomass of aquatic primary consumers but does not (Turner et al....
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Food Webs (FCE LTER)
Determining the sources, fate, and transport of dead organic matter is an important aspect of understanding the linkages between freshwater and marine environments in estuaries such as the Everglades. Comparative work among aquatic sites in the LTER network has shown that the dissolved form of organic matter is abundant in the Everglades but less biologically available compared to other estuaries...
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Unique Nutrient Sources (FCE LTER)
FCE research has shown that the Everglades operates differently from other coastal ecosystems in that its estuaries that are "upside-down", with seawater supplying limiting nutrients landward, rather than the other way around. Collaborative research with Caribbean scientists, particularly those associated with Mexican LTER programs (MexLTER), has shown similar upside-down features in similar...
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Importance of Household Decisions (CAP LTER)
Residential landscapes are a critical ecological feature of the urban ecosystem because they are widespread and are made up of highly designed and managed combinations of plants (e.g., landscaping) and animals (e.g., pets). For example, as Phoenix has urbanized, native Sonoran desert ecosystems have been replaced by an "urban oasis" that includes both lush, watered lawns and carefully managed...
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Urban Biodiversity (CAP LTER)
Most ecological theories are based on ecological patterns and processes in non-urban and less human-dominated environments. As cities grow and the global population becomes more urban, ecologists need to test their theories in urban settings and modify them, or even develop new ones, to reflect the ecology of cities. CAP scientists have used the special characteristics of urban food webs (i.e...
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Informing Urban Policy (CAP LTER)
Ecosystem services are the benefits that people receive from their life-supporting environment. These include the "goods" that nature provides to us (i.e. food, water, fiber, energy) as well as soil fertility, air and water quality, pest control, recreation, and aesthetics. Natural systems deliver these services, but humans have also designed or engineered ecosystems to deliver specific services...
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Urban Heat Island Effects (CAP LTER)
The Urban Heat Island Effect (UHI) is when a city is significantly warmer than the outlying rural area due to the preponderance of concrete and asphalt surfaces that store heat during the day and release it at night. While urban heat islands exist in most large cities, the Phoenix metropolitan area has presented a special case for the study of this phenomenon because of its rapid growth over the...
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Food Web Base (CCE LTER)
Every second breath you take is courtesy of the phytoplankton -- the tiny single-celled photosynthesizers in the ocean. The oxygen the phytoplankton produce has allowed the proliferation of life on earth, while the carbon dioxide they fix into organic carbon helps to regulate the planet's climate, and forms the base of nearly all ocean food webs. So it is clearly important to know how fast the...
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Iron Importance (CCE LTER)
It has been known for over a decade that the limiting micronutrient iron, supplied from shelf sediments, can fuel the productivity of the nutrient-rich coastal upwelling systems of central California. The significance of iron supply as a factor in community production in the more nutrient-poor waters of southern California, however, has been unstudied. Conventional wisdom would suggest that,...
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Marine Ecosystem Services (CCE LTER)
Sustained, high quality ocean measurements have been made in the California Current System for over 60 years, thanks to the far-sighted work of CalCOFI (the California Cooperative Oceanic Fisheries Investigations). This extensive program initially surveyed the ocean from Baja California, Mexico to the state of Washington, although today it samples a more restricted region from San Diego to San...
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Upwelling Matters (CCE LTER)
Years of previous research have focused on the process of coastal upwelling close to the continental boundary of the west coast of North America. A new study led by CCE-LTER (then) graduate student Ryan Rykaczewski and his advisor David Checkley identified, for the first time, important ecosystem contrasts between the strong nearshore upwelling in the classical coastal boundary region and the...
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Adapting to Change (BNZ LTER)
Changes in climate and fire regime are already affecting rural Alaskan communities where indigenous people have historically led a subsistence lifestyle as hunters, fishers, and gatherers. Warming has changed the timing of freeze up and melting of rivers and reduced the thickness of river ice and therefore reduced the safety of winter travel and access to some hunting grounds. Increased...
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Browse Control (BNZ LTER)
Studies of the interactions between vegetation processes and mammalian herbivory have been part of BNZ LTER research for over 20 years. We have found that browsing by moose and snowshoe hares controls vegetation development and nutrient cycling at a variety of scales. Mammalian herbivores control species composition, nutrient cycling, and plant population dynamics at the stand and landscape...
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Nutrient Sources (BNZ LTER)
Biogeochemical investigations have a long history at BNZ. These studies have demonstrated how slowly soil organic matter turn over in boreal forest soils, because of low biological activity coupled to a very short growing season. Recently, however, we have learned that nitrogen cycling in boreal forest soils continues past freeze-up and that about 40% of the annual nitrogen flux occurs during...
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Snow and Climate (BNZ LTER)
Modeling simulations over boreal Alaska have documented changes in albedo due to changes in the duration of the snow season and due to changes in the amount of young forest stands on a landscape due to changes in the fire regime. In addition, changes in the exchange of the greenhouse gases CO2 and methane have also been estimated due to changes in climate, atmospheric carbon dioxide...
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Critical Permafrost (BNZ LTER)
At least 1218 Pg (billion tons) of soil carbon (C) are stored in surface permafrost soils in boreal and arctic ecosystems, almost twice as much C than currently contained in the atmosphere (Tarnocai et al. 2009). Latitudinal gradients of soil C storage, field experiments, and laboratory incubations all show that soil C cycling in these northern ecosystems is likely to be strongly influenced by...
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Mapping Urban Lands (BES LTER)
Traditional land classifications in the US emphasized the contrast between urban or built-up versus wild or managed lands. Based on that fundamental split, urban lands have been subdivided into such categories as commercial, residential, transportation, industrial, and mixed urban. For some purposes, this relatively coarse classification is useful. However, scientists interested in the joint...
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Perceptions of Justice (BES LTER)
Twenty-five years of environmental justice scholarship shows that racial and ethnic minorities are more likely than whites to live near facilities that release toxins into the air, land, and water. Even when incomes are similar, racial and ethnic minorities are overrepresented in neighborhoods with polluting industry nearby. In Baltimore, we find an unexpected pattern -- white neighborhoods...
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