Key Findings

Co-authors Rob Olson and Heidi Sosik have worked on development of the FlowCytobot series of automated submersible plankton sensors at WHOI since the late 1990s Thanks to automated imaging approaches developed by NES LTER researchers, unprecedented insight has been gained into variations in microzooplankton biomass and diversity across a broad range of space and time... Read more »

Co-author Alexi Shalapyonok secures FlowCytobot (FCB) underwater at the Martha’s Vineyard Coastal Observatory (MVCO) tower. FCB, an automated submersible flow cytometer, operates unattended at MVCO for 6 months or longer, measuring thousands of individual microscopic plankton every hour. Phytoplankton bloom dynamics at Martha’s Vineyard Coastal Observatory (MVCO) are sensitive to temperature variability on both seasonal... Read more »

We are directly testing how climate mean and variance interacts by building the first field experiments that cross long-term drought with increased rainfall variability. Pulse-reserve theory has been a dominant conceptual framework for drylands since the 1970s. Detailed long term observations and experiments at the SEV LTER revealed that individual rainfall pulses rarely produce significant... Read more »

We characterized the sensitivity of biological soil crusts to drought (drought plot in photo) in dry grassland ecosystems (Fernandes et al. 2018). We also documented plant evolutionary responses to drought (Whitney et al. 2019) The climate of SEV LTER ecosystems has become drier and more variable during the past 100 years. SEV LTER research is... Read more »

Researchers at SEV LTER led efforts to characterize fungi and bacteria in drylands and document their responses to environmental change. SEV LTER pioneered new assays of microbial function, including carbon use efficiency and ecoenzymatic stoichiometry. They quantified how microbes in roots maintain plant species coexistence and temporal stability in plant communities and how biological soil... Read more »

Field technician Samuel Matta collecting water samples atop a climate tower in lower elevation forest Luquillo LTER uses an elevation gradient as a proxy for studying certain aspects of climate change. High elevation cloud forests on mountain summits harbor many endemic species likely to be threatened by the changes in precipitation and temperature projected to... Read more »

Student Celimar Rodriguez working on a seedling drought experiment Drought in tropical wet forest alters greenhouse gas production by soils, affects key nutrient dynamics, and reduces forest productivity. Downscaling studies at LUQ LTER support global models that predict declining precipitation through the end of the century. Current ecosystem drying and warming model projections predict that... Read more »

Luquilla field station, El Verde, after Hurricane Irma (just a few weeks before Hurricane Maria) Luquilla field station, El Verde, after Hurricane María Luquilla field station, El Verde, in 2020 The long term Canopy Trimming Experiment revealed many important aspects of hurricane disturbance, particularly that canopy opening caused more change in biota and biogeochemistry than... Read more »

Despite 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 modeling material... Read more »

A decade of nutrient enrichment significantly increased rates of oxygen uptake and nitrate reduction in sediment. Surprisingly, the proportion of the dormant microbial population increased (overall composition of the microbial community remained unchanged). This response to a perturbation may reflect the microbial community’s strategy for maintaining diversity in a highly dynamic environment.

For marshes where rates of sea level rise exceed about 3 mm/year, external sediment supply is critical to marsh survival. Although riverine sediment inputs to the Great Marsh are low, PIE LTER research has shown that marsh edge erosion during moderate intensity storms currently supplies enough sediment to maintain the marsh platform. However, with accelerating... Read more »

Long-term nutrient enrichment causes S. alterniflora habitat to collapse into the creek, limiting access to high-marsh invertebrates. Fish use more energy to access the high marsh which reduces trophic efficiency. In addition, these cracks also create crevasses where fish predators, such as American eel, can hide and feed on mummichog.Courtesy of the Integration and Application... Read more »

Konza Prairie Biological Station features a replicated watershed-scale experiment with contrasting fire frequency and grazing treatments. Fire frequency affects plant composition and ecosystem state (i.e. whether an ecosystem is grassland, shrubland, or woodland). Fire also affects nutritional quality and quantity of vegetation, which influences foraging decisions by large herbivores at multiple scales. Herbivore choices cascade... Read more »

Climate change forecasts for mesic grasslands include increased climate variability and extremes. Experimental climate manipulations at Konza Prairie reveal a spectrum of responses to climate change, ranging from a lack of resistance to extreme drought, to great resilience to increased precipitation and heat wave variability. Although community composition changes with climate extremes, tallgrass prairie resilience... Read more »

Experiments 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 after water... Read more »

Decades of research based on carbon stable isotope analyses supported the idea that macroalgal detritus, especially that of kelp, is a major source of food to coastal marine ecosystems, particularly suspension feeders. Comparative and experimental research from SBC LTER has overturned this paradigm, showing that phytoplankton, not kelp, are the main food resource for coastal... Read more »

Results from long term measurements and experiments reveal that climate-driven disturbances that alter giant kelp abundance cascade through the kelp forest community, affecting biodiversity and ecosystem function. These effects are due to kelp’s overwhelming influence on environmental conditions and habitat availability rather than its effects as a food source for fauna.

Fire 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 are advected offshore... Read more »

A marine heat wave of extreme magnitude and duration in 2014-15 allowed SBC LTER researchers to test predictions about the effects of climate change on kelp forests. Although kelp was diminished by the prolonged high temperature and low nitrate conditions, it rebounded quickly, and most other flora and fauna were not greatly affected. Ocean sampling... Read more »

A recent shift in the Alaska fire regime has increased the frequency and size of high-severity fires that combust deep organic layers, exposing mineral soil and favoring the invasion of hardwoods. Within the BNZ LTER Regional Site Network, many sites that were dominated by black spruce prior to burning in 2004 have now converted to... Read more »

Increases in air temperatures and depth of insulating snow cover during winter are accelerating the rate of permafrost thaw. In areas of ice-rich permafrost, widespread thermokarst is having significant consequences for biogeochemical cycling and surface hydrology. Measurements across latitudinal gradients, field experiments, and laboratory incubations all point to significant releases of CO2 and CH4 from... Read more »

Climate-related changes in environmental conditions are challenging rural residents' ability to traverse the land and access subsistence resources. Local residents observe that warming has changed the timing of freeze up, affected river ice thickness and melt, and has reduced winter travel safety and access to local ecosystem services. Wildfire reduces access to the land, threatens... Read more »

Browsing by snowshoe hares and moose have dramatic top-down influences on vegetation composition, successional dynamics, and ecosystem function throughout interior Alaska. 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... Read more »

Recent models indicate that lengthening of the snow-free season and associated declines in surface albedo constitutes the largest positive feedback to climate warming in the boreal forest. Models that assess climate feedbacks over the next century have simulated decreases in albedo due to a shorter snow season, wider extents of deciduous forest due to altered... Read more »

Pleuronocodes planipes, the pelagic red crab, which increases markedly in abundance in the CCE region during most El Niños. California Current Ecosystem LTER researchers published a cluster of 5 papers in Deep-Sea Research (vol. 140, Oct. 2018) that analyzed biotic responses to two successive perturbations of the California Current pelagic ecosystem: the Warm Anomaly of... Read more »