Cold Air Drainage Flows Subsidize Montane Valley Ecosystem Productivity

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Landscape ecologists and nature-lovers are well aware of the way that valleys collect deeper, moister soils than neighboring hill slopes and crests. Now, researchers at Coweeta LTER have have found that cool air, sliding downslope from higher elevations and pooling in mountain valleys, subsidizes productivity in a different way. The cold air drainage was most prevalent at night and in the evenings, so it had little effect on photosynthesis, but reduced plant and soil respiration by about 8 percent. Overall, the authors estimate it boosted annual net carbon uptake by about 15 percent.

Genetic Differences May Help Corals Adapt to Changing Conditions

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Individuals—even individuals of the same species—don’t always respond to a stimulus in the same way. Studying calcification in a key coral species, Acropora pulchra, researchers at the Moorea Coral Reef LTER found greater variety in the corals’ response to temperature than to high levels of CO2 in seawater. Since individual variation is the raw material of evolution, the contrast suggests it may be easier for this coral species to adapt to rising temperatures than to increased ocean acidification.

The Spruce and the Hare: Backing Up Leopold’s Intuition

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Snowshoe hares prefer many other plants to white spruce seedlings, but when the population of hares skyrockets—as it does about once a decade—they can decimate even a bumper crop of spruce seedlings. Researchers with the Bonanza Creek LTER reconstructed over 40 years of browsing history by analyzing the age and browse scars of thousands of seedlings and saplings at 18 locations on the floodplain of Alaska’s Tanana River.

Urban Streams Cycle Nitrogen as Fast as Unbuilt Systems

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Urban watersheds—with their fertilized lawns, street runoff, treated and untreated wastewater—have proportionally more nitrogen flowing through them than undeveloped landscapes do. But are urban streams somehow less able to process that nitrogen? New research out of the Baltimore Ecosystem Study LTER says: no. The study, based on 385 urban watersheds and published in the journal FEMS Microbial Ecology, found that urban watersheds have similar, if not higher, nitrogen processing rates than natural areas.

Divergent water regimes influence algal diversity

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Wetlands exist on every continent save Antarctica and manifest as a variety of habitats, from salt marshes to mangrove forests. They provide important ecosystem services, such as water purification and flood protection—often tied to their high productivity and diversity.

Macrosystems ecology: A key subfield matures

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Ecosystems ecology, landscape ecology, macrosystems ecology. It’s easy to think of these subdisciplines as big, bigger, biggest—but there’s a good deal more to the distinction than the scale of interaction they address. A recent “Idea and Perspective” article in Ecology Letters traces the origins and foundations of the field of macrosystems ecology, and advances a new hypothesis to describe how anthropogenic influences change the scales of ecological processes.

The grazing effect: How bison impact plant water use

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When one envisions a grassland community, imagery of tall grasses and bison often come to mind. Bison are an iconic species on the landscape, and they also impact the structure and function of the grassland ecosystem in important ways.  Using natural variations in the abundance of oxygen isotopes, researchers at the Konza Prairie LTER found that  grazing influenced plant water use through changes in diversity.

Putting the “urban” in disturbance: Applying ecological frameworks to cities

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The concept of “disturbance” is a core theme of the LTER Network and central to ecological science. How does the idea of disturbance need to change when applied to the interactions of an urban metropolitan region rather than a “natural” system? Ecologists often consider the process of urbanization itself to be a form of disturbance, but that is a habit that has to change, say the authors of a recent paper in Ecosystem Health and Sustainability. People, technology, and infrastructure have to be defined as part of the system when studying cities, they say.

Chronic Nitrogen Enrichment Slows Fungal Action

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Fungi, often spotted in cold, damp locations, are responsible for decomposing the plant litter that falls to forest floors, enriching soils. Without fungi, dead plant material would inundate ecosystems and overwhelm other organisms. What would happen, then, if anthropogenic nitrogen altered the fungi’s ability to perform this vital ecosystem function? A recent study capitalized on a 28-year nitrogen enrichment experiment at the Harvard Forest LTER site in north-central Massachusetts to find out.  As nitrogen inputs to a system increase, researchers found, fungal decomposition slowed.