As cities grow, researchers want to understand ecological systems as they exist in heavily urbanized areas. For example: How do biological, physical and social systems interact in a mostly engineered landscape? How can studying these interacting systems inform decisions around city planning and resource management, with the goal of creating more sustainable cities?
In particular, urban areas in the Southwestern U.S. and other arid regions present unique sustainability challenges and opportunities. The Central Arizona-Phoenix LTER site is one of two urban LTER sites supported by NSF where researchers study the urban ecology of a complex, dynamic system. Scientists here generated new insights about urban ecosystems, such as improved storm-water management approaches, that urban planners and policymakers have used to design cities.
Scientists at the Palmer Antarctica LTER site have documented an 85 percent decline in the Adélie penguin population over the past 40 years. Adélie penguins, like the ones pictured here, depend on ice platforms to forage for food. As temperatures rise, sea ice declines, making it more difficult for Adélie penguins to survive.
At the same time, other species are more amenable to the changing environment. Chinstrap and Gentoo penguins, for example, are less dependent on sea ice for their survival and have immigrated into some of the strongholds once dominated by Adélie penguins. In addition to changes in the penguin populations, Palmer Station researchers track changes in sea ice and the marine food web, and pioneered the use of underwater gliders to explore below the Antarctic waters.
The controlled fire pictured here is burning away biomass at the Konza Prairie LTER site in the Flint Hills region of northeastern Kansas. Home to the largest, most productive area of unplowed tallgrass prairie in North America, the site provides a benchmark for exploring the drivers and impacts of environmental change taking place throughout the grasslands of the eastern Central Plains.
Fire helps maintain prairie ecosystems by clearing away the dead leaf litter that can build up and crowd out sunlight for new plant shoots. Konza Prairie scientists pioneered the use of long-term, large-scale fire and grazing experiments to understand the ecological effects of fire and grazing in grasslands. Today, fire is used as a tool to manage and conserve tallgrass prairies.
Poppies abound in the Chihuahuan Desert, where the Jornada Basin LTER site is located. Since 1982, researchers at this arid, semi-arid site have studied dramatic changes in vegetation, as perennial grasslands give way to shrubland in a process known as desertification. Nearly 40 percent of Earth’s land surface and a fifth of the world’s population are impacted by desertification, and long-term research at Jornada provides insights into the causes and consequences.
Research conducted at NSF’s LTER sites provides valuable data on the resilient qualities and vulnerabilities of our changing planet.
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A tricolored heron perches on a branch in a salt marsh along the Georgia coast. Herons and other coastal species are likely to experience substantial change over the coming decades, as rising temperatures and sea level alter the look and function of their ecosystem.
Researchers at the Georgia Coastal Ecosystems LTER site are monitoring and documenting many of these changes among different coastal habitats, including barrier islands, salt marshes, rivers and estuaries. Their research elucidates the patterns and processes that shape estuarine and marsh environments.
In this picture, high winds scour the Taylor Valley, removing much of the snow and ice, in Antarctica’s McMurdo Dry Valleys. The Dry Valleys form the largest, relatively ice-free area on a continent otherwise buried under ice. Moss, lichens and microorganisms flourish in this cold, desert region, where higher life-forms are mostly nonexistent.
In Antarctica, even small variations in temperature can give rise to rapid and dramatic changes. Researchers operating from the McMurdo Dry Valleys LTER site brave hostile conditions to better understand questions about biodiversity, the impact of a changing climate, and the structure and function of the Dry Valleys ecosystem.
Mountain ecosystems are some of the most vulnerable to ecological change. For more than three decades, researchers have studied environmental change at the Niwot Ridge LTER site. The entire site sits at an elevation of 3,000 meters in Colorado’s Rocky Mountain range and is characterized by alpine tundra, glacial lakes, permafrost and other features.
Like many mountain ecosystems, Niwot Ridge serves as an important “water tower,” regulating downhill water flow as snowmelt replenishes lakes and streams at lower elevations. High-elevation ecosystems are also sensitive to, and indicators of, air pollution. Colorado land managers use the findings from Niwot Ridge to determine limits on emissions of nitrogen pollution associated with industry and agriculture.
The 16,000-acre H.J. Andrews Forest LTER site in Oregon’s western Cascade Mountains embodies the mountainous, forested landscape of the Pacific Northwest. Old-growth conifer and mature forest, steep terrain and fast-moving streams characterize this unique ecosystem, which is home to black bears, bobcats, mountain lions, elk, rainbow trout and other animal species.
Incorporated as an LTER site in 1980, Andrews Forest was one of the founding sites in NSF’s national network of ecological research sites. Scientists at the site have informed a number of forest management plans and policies in the Pacific Northwest. For example, the Northwest Forest Plan helps conserve old-growth forests, watersheds and species, while maintaining timber and other resources for communities in the region.
From the planet’s polar regions to its deserts and oceans, environmental changes are underway. Sometimes the changes are visible and dramatic—as when a Manhattan-sized iceberg breaks away from an ice shelf. Other times, changes in an ecosystem are more subtle, occurring over a span of decades.
In 1980, the National Science Foundation (NSF) launched the Long-Term Ecological Research (LTER) program to study ecological phenomena over long periods of time at sites representing a diverse range of biomes. Today, NSF supports 28 LTER sites across the U.S., Puerto Rico, French Polynesia and the polar regions, some of which are featured in this gallery. Scientists at these sites increase the understanding of complex ecosystems and give society the knowledge and tools to address environmental challenges.
Pictured: Harvard Pond is located within the 1,200-hectare Harvard Forest LTER site in north-central Massachusetts, where researchers have transformed scientific understanding of the role invasive species play in disrupting forest growth.
To learn more, go to nsf.gov.
The colorful tundra landscape pictured here is part of the Arctic LTER site in the northern foothills of Alaska’s Brooks Range (seen here in background). The serenity of the image belies a tumult of change. Over the past 30 years, the Arctic region has warmed significantly.
Researchers at the site study how Arctic lands and freshwater lakes and streams respond to changing environmental conditions. A technique to investigate the nitrogen cycle of streams, which was first developed at the Arctic LTER site, transformed scientists’ understanding of the nitrogen cycle in relation to food webs in flowing waters. The technique is now applied widely to understand how streams transport and process nitrogen.
This Christmas tree worm makes its home at the Moorea Coral Reef LTER site in French Polynesia. Coral reefs are some of the most productive and diverse ecosystems in the world. In the short term, they face disturbances such as overfishing. Over the long term, more chronic threats such as rising temperatures and ocean acidification threaten their survival.
Researchers at the Moorea site have been active in developing the cyberinfrastructure for a sensor network that would provide real-time environmental data to enable better management of the reef ecosystem. Moorea is currently a node in the global Coral Reef Environmental Observatory Network.
The Shark River tributary pictured here is part of the Shark River Slough, or swamp, one of two major drainage basins for Florida’s Everglades National Park. Researchers associated with the Florida Coastal Everglades LTER site study this estuarine area, where salt water from the ocean meets and mixes with freshwater from the land.
Compared to upstream marshes, which are typically nutrient-poor, the Shark River swamp region is nutrient-rich thanks to phosphorous provided by seawater. Researchers at the site are studying the interaction of freshwater restoration efforts, sea-level rise and water management decisions. Everglades scientists worked with an intergovernmental task force to establish a transparent reporting system that assesses the progress of ecosystem restoration efforts.