The study site, located in southwest of Toulouse (France) is a typical agricultural landscape (agricultural mosaic + forest remnants) with mixed production systems. This region is considered as an “intermediate zone”, without any particular conservation value, any agricultural potential, and any social challenge. The total study site area is around 15 000 hectares. Agriculture remains the predominant activity, but it is encountering difficulties in marginal areas that do not have particularly high agricultural potential.

The Niwot Ridge (NWT) LTER site was one of the five original LTER sites established in 1980. The LTER program is based at the University of Colorado-Boulder and is administered through the Institute of Arctic and Alpine Research (INSTAAR) and in cooperation with the Mountain Research Station, with special use permits from the US Forest Service.

The California Current System is a coastal upwelling biome, as found along the eastern margins of all major ocean basins. These are among the more productive ecosystems in the world ocean. The California Current Ecosystem (CCE) LTER site (centered on 32.9° N, 120.3° W) is investigating nonlinear transitions in the California Current coastal pelagic ecosystem, with particular attention to long-term forcing by a secular warming trend, multi-decadal oscillations (e.g., PDO and NPGO), and ENSO in altering the structure and dynamics of the pelagic ecosystem.

The Central Arizona–Phoenix Long-term Ecological Research (CAP LTER) project is based in the central Arizona and metropolitan Phoenix region, embedded in the Sonoran Desert. As the fifth-largest and, until recently, the fastest-growing city in the US, Phoenix is an excellent location for urban ecological research. Phoenix was established after the Civil War, initially one of several small towns surrounded by irrigated farmland. Continued agrarian expansion predated the explosive growth of housing in the second half of the 20th century.

The Sevilleta LTER is located at the intersection of several aridland ecosystem types. Although it is axiomatic that water is the key limiting resource in aridland ecosystems, most arid land soils are also chronically low in nutrients and organic matter. Resource availability is a function of the frequency and size of precipitation events as well as the time between events. As a consequence, NPP and organic matter decomposition are often decoupled in space and time, and soil nutrient supply rates may limit NPP during periods when soil moisture is sufficient for plant growth.

The goal of the Arctic LTER is to predict the future ecological characteristics of Arctic Alaska based upon our knowledge of the controls of ecosystem structure and function as exerted by physical setting and geologic factors, climatic factors, biotic factors, and the changes in fluxes of water and materials from land to water.

The Georgia Coastal Ecosystems (GCE) LTER site, located on the central Georgia coast, was established in 2000. The study domain encompasses three adjacent sounds (Altamaha, Doboy, Sapelo) and includes upland (mainland, barrier islands, marsh hammocks), intertidal (fresh, brackish and salt marsh) and submerged (river, estuary, continental shelf) habitats. Patterns and processes in this complex landscape vary spatially within and between sites, and temporally on multiple scales (tidal, diurnal, seasonal, and inter-annual).

The Cedar Creek LTER (CDR) is housed at the University of Minnesota’s Cedar Creek Ecosystem Science Reserve (CCESR), an internationally renowned ecological research and education facility, located 35 miles north of the Twin Cities. Established in 1942, Cedar Creek encompasses 2,200 hectares of land comprised of a unique and diverse mosaic of forests, savannas, prairies, wetlands, and open water.

Coastal ecosystems play a key role in the transformation, transport, burial and exchange of water and organic and inorganic carbon and nitrogen between land, atmosphere and the ocean. With an overwhelming majority of the human population living in the coastal zone, coastal ecosystems are among the most heavily impacted ecosystems in the world. Like many other coastal regions, the Plum Island Ecosystem region, which lies just north of Boston, Massachusetts, is experiencing population growth in the watershed, land use change, climate change, altered hydrologic cycles, and sea level rise.

The Shortgrass Steppe (SGS) LTER project studies an ecosystem that has persisted under a regime of semi-arid extremes, with high inter- and intra-annual variability in precipitation and temperature. The 340 mm of annual precipitation falls primarily during spring rainstorms over several days as well as during a period of summer rains from more localized thunderstorms. Further, the system is well-adapted both to grazing by large herbivores and to smaller-scale disturbances caused by animals like prairie dogs.