Connectivity Plays a Key Role in Vegetation Dynamics

Jornada Basin LTER
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 »

Sources of Groundwater Recharge

Jornada Basin LTER
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 »

Rodent Biomass Linked to Precipitation

Jornada Basin LTER
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 »

The Power of “Big Data”

Jornada Basin LTER
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.  

A Single Extreme Summer has Long Lasting Impacts

McMurdo Dry Valleys LTER
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 »

Climate and Hydrology Changes are Altering Soil Communities

McMurdo Dry Valleys LTER
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.

Phytoplankton are sensitive to nutrients and light

McMurdo Dry Valleys LTER
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 »

Connectivity Matters in a Rapidly Changing Environment

McMurdo Dry Valleys LTER
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 »

Significance of Lake Moats

McMurdo Dry Valleys LTER
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 »

Ocean Acidification is an Emerging Threat

Moorea Coral Reef LTER
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 »

Unprecedented Resilience of Coral Communities

Moorea Coral Reef LTER
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 »

Coral Reefs are Vulnerable to Disturbances

Moorea Coral Reef LTER
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 »

Microbes and the Future of Coral Reef Function

Moorea Coral Reef LTER
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 »

Divergent Consequences of Climate Change

North Temperate Lakes LTER
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.

Anticipating Regime Shifts in Ecosystems

North Temperate Lakes LTER
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 »

Lakes are Full of Diverse Microbes

North Temperate Lakes LTER
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 »

Stratification is Changing

Northern Gulf of Alaska
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 »

Trophic Effects of 2015-16 Warming Event

Northern Gulf of Alaska
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 »

Modeling Illuminates Eddy-induced Cross-shelf Transport

Northern Gulf of Alaska
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 »

Keystone Species Ranges are Changing

Palmer Antarctica LTER
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 »

Ecosystem Resilience

Palmer Antarctica LTER
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 »