Winter Conditions Vital to Year-Round Lake Dynamics

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This month’s Ecology Letters features the first global quantitative synthesis of under-ice lake ecology. In their analysis of 36 abiotic and biotic variables across 101 lakes, the authors issue a call to arms for more winter lake research—currently the focus of only 2% of freshwater publications. As the climate warms, they warn, temperate ecosystems are losing ice, and limnologists remain unsure what ecological processes are at stake. Though winter has long been understood as an inactive period, some data suggests that winter foodwebs and physical processes remain vigorous and that winter ecology can drive subsequent summer conditions.

Coastal Everglades in the Cold: Mapping Ecological Sensitivity

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How sensitive are coastal ecosystems to sharp changes in temperature? Using a detailed spatial analysis in the Florida Everglades, researchers found that cold snaps reduced ecosystem productivity most dramatically in areas with low water levels that were located away from the coast. With more extreme weather events predicted in the future, knowing the likely effects of low temperature events on subtropical wetlands systems can inform management of these important ecosystems.

Finding the Hidden Phytoplankton Blooms

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In stratified lakes, a large portion of phytoplankton biomass is found—not at the surface, where sampling is easiest—but somewhere down the water column, in what is known as a subsurface chlorophyll maximum (SSCM). Researchers in Global Lake Ecological Observatory Network (GLEON) compared automated high-frequency chlorophyll fluorescence (ChlF) profiles with surface samples and discrete depth profiles. In 7 of the 11 lakes studied, automated sampling captured the presence of SSCM’s that would have been missed by conventional sampling.

What (and when) is the point-of-no-return?

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How-and when-do ecosystems change character? Are those shifts reversible? And what signs might precede them? Such questions are hard enough to answer in a single place. One might think that incorporating different kinds of ecosystems would only complicate the problem. But a group of scientists in the Long-Term Ecological Research Network is finding a remarkably consistent pattern by combining models and data across several long-term ecological experiments.

Climate variability predicted to affect outcome of exotic grass invasion

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Novel ecosystems can emerge through many kinds of changes, including changes in mean climate, species invasions, and increased or decreased variability. Researchers at Jordana Basin LTER have highlighted the role of interannual climate variability in changing the outcome when an exotic grass species invades dry shrubland. Using a process-based model, they predicted three outcomes, depending on the degree of variability and timing relative to invasion.

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 hare

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.

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.

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