Key Findings

Connectivity modifying structures (ConMods) trap and retain wind-transported seeds and organic material, reducing connectivity and facilitating local recruitment. Locations that are functionally connected in the landscape experience greater materials and energy transfer, which ultimately influences spatial and temporal vegetation dynamics in desert landscapes. In pilot studies, small connectivity modifying structures (ConMods) increased grasses and forbs... Read more »

Researchers conduct fieldwork in the Chihuahuan Desert of New Mexico. Using long term observations and a water balance approach, JRN LTER researchers determined that small watersheds on piedmont slopes are large contributors to groundwater recharge on the Jornada Basin. This was one of the first studies to quantify groundwater recharge in arid region first-order watersheds.... Read more »

Late fall switchgrass harvest at the GLBRC / KBS LTER biofuels scale-up site; Photo Credit: J.E.Doll, Michigan State University Research from KBS LTER reveals not only how changes in cropping practices improve ecosystem service flows, but also the economic value of those flows. Paired studies of farmers and consumers track farmer willingness to provide changed... Read more »

Kangaroo Rat Desert rodent biomass depends on an interaction between shrub cover and precipitation – more rodent biomass is associated with grasslands following droughts and with shrublands following wet years. This pattern can be largely explained by the irruption of folivores (which prefer shrubbier vegetation) during wet years and suggests that rodent population dynamics are... Read more »

Organ Mountains-Desert Peaks National Monument Researchers at JRN LTER are incorporating machine learning into complex dataset exploration. The data exploration interface is capable of suggesting potential analytical approaches to new users based on interactions with previous users.  

During a decadal cooling period, productivity and hydrological connectivity synchronously decreased among terrestrial and aquatic ecosystems. As summer air temperatures and solar radiation stabilized in the following decade, the ecosystem moved back toward pre-cooling period conditions but in an asynchronous manner. This was due in part to the fact that the end of the cooling... Read more »

Soil invertebrate communities in long term monitoring plots are responding to long term and seasonal changes in temperature and water availability, with key taxa exhibiting distinct responses. These changes are favoring rarer hydrophilic taxa, while the dominant species, an endemic free-living nematode which prefers cold dry soils, is declining in monitoring and experimentally manipulated plots.

Photosynthetic and mixotrophic eukaryotes are the dominant primary producers in the stratified water columns of the dry valleys lakes. Nutrient amendment experiments have shown that growth of chlorophytes, an obligate photosynthetic phytoplankton group, are stimulated by the addition of nitrogen or phosphorus in Lake Fryxell and nitrogen in Lake Bonney. Conversely, when communities are transplanted... Read more »

Record melt and thaw events over the past decade have increased the physical connectivity of the McMurdo Dry Valleys ecosystem. Researchers at MCM LTER have tested hypotheses that focus on responses, such as increased biogeochemical cycling and changes in biodiversity. These studies suggest that landscape morphology is changing as permafrost thaws, and that biological communities... Read more »

In the austral summer, the shallow margins of ice-covered lakes melt, forming moats around the permanent ice covers of the lakes. Waters here interact with streams, soils, and the atmosphere (unlike those under the permanent ice). Recent study of these moats has uncovered these as the locations of the highest biomass per unit area in... Read more »

Researchers at MCR LTER have been at the forefront of evaluating how OA will affect the structure and function of future reefs. The ecosystem engineers that structure coral reefs – stony corals and calcified algae – are uniquely threatened by low seawater pH. Using time series data to determine experimental conditions, researchers have tested for... Read more »

The diverse coral community on Moorea’s outer reefs has repeatedly shown a remarkable ability to recover rapidly following massive disturbances. In the last decade, a predator outbreak and cyclone devastated coral across the seascape, yet recovery was more rapid than has been observed anywhere in the world. Moorea Coral Reef LTER researchers have gained critical... Read more »

Reefs worldwide have abruptly and increasingly shifted from coral to seaweed dominated communities. Experiments at MCR LTER revealed that a large disturbance can cause a coral reef to flip to seaweeds indefinitely. Experiments and models showed that multiple stable states (e.g. corals or seaweeds) can continue to thrive under the same levels of herbivory. They... Read more »

The powerhouse mutualism between the coral animal and its symbiotic dinoflagellate algae is the backbone of coral reef ecosystems. Moorea Coral Reef LTER research has produced counter-intuitive results, specifically that flexibility with respect to symbionts does not automatically make corals resilient – a finding that has had profound implications for understanding the susceptibility of coral... Read more »

Long term records show declining ice duration, lake warming, and increased variability in decadal lake level cycles. However, the magnitude of these physical changes, and their ecological consequences, differ substantially among lakes, including differences in warming rates, shifts in fish populations, and fluctuations in water clarity.

Terrestrial organic carbon (C) entering lakes can be stored, sent to the atmosphere as CO2, or passed downstream. Long term measurements of hydrology and C were used to understand and model the fate of terrestrial C in lakes. In Wisconsin’s 6,400 km2 Northern Highland Lake District (NHLD), the fraction of organic C converted to CO2... Read more »

Regime shifts are large, persistent, and often abrupt changes in ecosystem structure and function that may be difficult to reverse. Through long term whole ecosystem experiments and measurements, NTL LTER researchers have described regime shifts involving lake eutrophication and food web structure, and have used these case studies to develop conceptual and mechanistic models. These... Read more »

Long term pre-invasion records provide an essential baseline for understanding invasive species effects, which can have profound consequences for ecosystems and society. In a key example, the spiny water flea invaded Lake Mendota, leading to massive declines in water quality and a loss in ecosystem services valued at $140 million.

Although bacteria play a central role in processes affecting lake water quality, the taxa participating in these activities are largely undescribed. To address this knowledge gap, NTL LTER researchers have generated the largest freshwater microbial genome collection to date. These studies reveal a paradoxical pattern of large differences in community structure over time and among... Read more »

The coastal Gulf of Alaska water column is becoming progressively more stratified — the entire water column is warming, but more rapidly at the surface than near the seafloor, while near surface waters are becoming fresher. This is due to multiple factors including the air-sea heat flux, ocean heat flux convergences, the stabilizing influence of... Read more »

Reductions in primary producer average cell size and biomass followed the 2015-2016 warming, as did corresponding reductions at higher trophic levels. In addition, southern zooplankton species of smaller body size invaded the region and anomalous increases in gelatinous zooplankton population were observed. These changes, which could represent a window into the future of the Northern... Read more »

Although glacial input leads to high iron concentrations during summer and fall within the narrow Alaska Coastal Current, the ratio of iron to nitrate over the Northern Gulf of Alaska shelf in spring can be low enough to lead to nutritional stress in diatoms. This mismatch in essential nutrients likely affects phytoplankton community evolution during... Read more »

Modeling at NGA LTER investigates how the complex interplay between the strongly seasonal freshwater discharge at the coast and offshore eddies controls horizontal gradients of limiting nutrients (nitrate and iron). This work builds on previous modeling studies in the region that utilized Seward Line observations to improve the accuracy of simulated physical and biogeochemical fields.... Read more »

Shifts in sea ice are affecting the WAP ecosystem and biogeochemistry. Despite dramatic shifts in Antarctic food webs, the number of the keystone krill species (Euphausia superba) has not changed significantly over the PAL LTER study area. However, researchers have observed reduced juvenile recruitment following positive anomalies of the Southern Annular Mode. North of PAL... Read more »

Between 2010 and 2017, the PAL LTER study area experienced cooler winter air temperatures, cooler summer surface ocean temperatures, and longer ice seasons relative to the first decade of the 21st century (but not relative to the 1950s-1970s). This has slowed sea ice declines, which is associated with increased primary productivity and ocean CO2 drawdown.... Read more »