Controls on Nitrogen Fluxes to Estuaries

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Credit: Andrew RobisonDespite expanded suburban development, nitrogen fluxes to the estuary have remained steady since the early 1990s. River flow, which is becoming more variable along with climate, largely determines nitrogen retention. Imbalances between nutrient supply and demand reduce nutrient regulation during higher flows. Work at PIE LTER helped lead to a generalized framework for… Read more »

Consumers Respond Unexpectedly to Nutrient Enrichment

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For the first six years of an ongoing 13-year nitrate addition experiment in tidal creeks, benthic algae, invertebrate prey, and a small fish, the mummichog, showed a classic positive bottom-up response to added nutrients. However, after six years, creek banks began to collapse and mummichog abundance in fertilized creeks declined relative to reference sites, likely… Read more »

Non-Equilibrium Dynamics are Nearly Ubiquitous and Spatially Complex

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Credit: Jill HaukosExperiments at KNZ LTER have identified significant time lags between treatment initiation and sustained community effects. At a minimum, these times lags are 3-6 years for water and nutrient manipulations, but can be decades according to fire suppression and woody plant expansion studies. Decreases in plant diversity evident in the first few years… Read more »

Fires Mobilize Nutrients to the Ocean

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Credit: SBC LTER/Dan ReedFire and land use affect the amount and timing of nutrient organic matter and sediment delivery from watersheds to the ocean. Drought and fire followed by rain causes large fluxes of terrestrial nutrients to the coastal ocean. During storms, runoff plumes containing high concentrations of nutrients remain close to the coast, but… Read more »

Browsing by Large Herbivores Influenced Ecosystem Function

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Browsing by moose and snowshoe hares affects plant species composition, growth, population dynamics, nutrient cycling, and ecosystem function at both stand and landscape scales, causing effects that can persist for decades. Both species selectively consume willows, leading to the dominance of alder, an important nitrogen-fixing species that is chemically defended against herbivory. Snowshoe hare abundance… Read more »

Can seagrass meadows mitigate climate change?

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As anthropogenic carbon dioxide emissions continue to increase, scientists have now recognized seagrass meadows—which typically have high rates of carbon storage—as important ‘blue carbon’ sinks. However, rising ocean temperatures threaten seagrass meadows, along with their ability to retain carbon. This underlines the need for precise ecosystem data on the vulnerability and resilience of these meadows… Read more »

LTER at Ocean Sciences Meeting 2020

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In 2017, the LTER Network saw the addition of three new marine and coastal sites. The new sites—Northeast U.S. Shelf (NES), Northern Gulf of Alaska (NGA) and Beaufort Lagoon Ecosystems (BLE)—are all well-represented among the 41 talks and posters presented by LTER researchers at the 2020 AGU Ocean Sciences Meeting. Presentations from these and other… Read more »

Cold, Dry, and Phosphorus Limited: microbial activity in nutrient poor habitats

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rocky, mountainous landscape

High elevation and high latitude ecosystems are particularly vulnerable to climate change impacts because they represent the upward range limits for organisms that are adapted to cold temperatures and low nutrient levels. Two of the biggest threats to high elevation communities are nutrient deposition (e.g. nitrogen) and climate warming. A new study by Bueno de… Read more »

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