Long Term Ecological Research (LTER) Network Office
The hub for synthesis research, education, and outreach activities across a set of 26 ecosystem research programs
The Long-Term Ecological Research (LTER) Network is a set of 26 National Science Foundation-funded research programs located in a wide variety of ecosystems. Because this research relies on collaboration and years of data, NCEAS operates the LTER Network Office, which serves as a hub for LTER synthesis research, education, and outreach activities.
LTER research enables the long-view. Changes such as forest growth, desertification, the rebound of an endangered species, and sea-level rise happen over decades and can often have unpredictable effects. Studying how and why ecosystems change over the long term is essential to managing our natural resources sustainably and ensuring the health and prosperity of our communities.
The Network Office’s programs integrate the science conducted at the individual sites into a robust understanding of how diverse ecosystems function across space and over time. It also ensures scientists, educators, resource managers, and decision makers have greater awareness of and access to this valuable science.
Synthesis Skills for Early Career Researchers (SSECR)
The LTER Network Office offers the Synthesis Skills for Early Career Researchers (SSECR; [SEE-ker]) course in even-numbered years (2024, 2026, and 2028). Course participants gain the technical and interpersonal skills needed to assemble, scope, manage, and communicate a team-science synthesis project. Small groups put the lessons into immediate practice through a team science project that they plan during the semester and may opt to continue pursuing. Instructors include LTER Network Office facilitators and data scientists as well as experienced leaders of successful synthesis science projects.
Specific course priorities include:
- Surface and test new synthesis ideas for feasibility
- Prepare more graduate students to be effective participants in/leaders of the synthesis projects
- Connect LTER graduate students across sites
- Develop intergenerational linkages around synthesis research
A course website links to completed projects and assembles the instructional materials (we'd love to see them used by others running similar programs).
Synthesis Working Groups
The Network Office periodically funds synthesis working groups to expand the scope of LTER science. These teams integrate insights from multiple ecosystems to generate a broader understanding, often with implications for management.
To get notifications of calls for proposals and other LTER news, subscribe to the LTER newsletter.
2025 Working Groups
LTER: Integrating above-and belowground community data to understand ecosystem temporal dynamics and responses to global change
Interconnectedness between plant and microbial communities is likely a key indicator of ecosystem functioning and stability. These associations could be assessed through synchrony, the degree of similarity in temporal fluctuations between different ecosystem components, and coupling, which is the pairwise association of components in the ecosystem. However, few studies have monitored both above- and belowground components simultaneously and repeatedly over time, potentially leading to incomplete representations of community temporal dynamics. We propose to compile multi-year, co-located data on plant and microbial communities to test hypotheses related to the drivers of above- and belowground community synchrony and coupling in response to environmental change.
LTER: Life after death: how legacies of dead foundation species influence ecological processes across marine and terrestrial ecosystems
While there is widespread appreciation that abiotic/climate legacies strongly influence community assembly and ecosystem resilience, there is emerging evidence that another type of legacy—structural and resource remnants left by organisms—may exert as strong or stronger effects. The remnants of foundation species (e.g., dead trees, corals, oysters, and grasses) are likely highly influential, as these abundant organisms can leave behind pervasive legacies after they die. We are beginning to piece together the importance of these effects in specific ecosystems (e.g., coral reefs, grasslands, forests), but how and why these effects vary among ecosystem types remains largely unexplored. Leveraging the LTER network, we will explore how material legacies of dead foundation species affect the demography of their living counterparts across a range of marine and terrestrial ecosystems, spanning the tropics to the Arctic Circle.
Temporal variation in taxonomic and functional diversity and nutrient cycling of consumers across aquatic ecosystems and LTER sites
Recent advances in trait-based frameworks, that utilize universal functional traits to examine functional diversity, provide a critical opportunity to better understand patterns in diversity across taxa with diverse phylogenetic lineages, especially in response to global change. While ecologists have had much success using universal traits for plants with diverse origins, methodologies in consumer studies are generally disparate, often focusing on one group, process or system. Here we aim to bridge the gap in our understanding of consumer functional diversity and ecosystem function by utilizing a universal functional traits framework. We propose to quantify temporal variation in taxonomic and functional diversity, and nutrient cycling by integrating universal functional traits, process rates data, and population time-series data of consumers across aquatic ecosystems.
2024 Working Groups
LTER: Assessing the resilience of productivity to climate variability across management and climate gradients
Ecologists have long focused on understanding the patterns and drivers of primary production across diverse terrestrial ecosystems as it serves as the foundation of ecosystems and food webs worldwide, drives global carbon cycling, and is an important provisioning resource. However, the vast majority of these cross-site syntheses have been done in natural, unmanaged systems (e.g., LTER) with considerably less attention paid to managed ecosystems (e.g., rangelands, croplands), despite their proportionally larger extent of the global landscape and crucial role in feeding and clothing the human population. Here we propose to combine LTER data with two other prominent research networks - the Nutrient Network (NutNet) and the Long-Term Agricultural Research Network (LTAR) - to capture land uses underrepresented by the LTER network and examine the effects of management and climate on production resilience.
LTER: Consumer Absence Generates Ecological Dissimilarity (CAGED): A cross-ecosystem synthesis exploring the consequences of consumer loss on community variability
Ecosystems around the world are facing dramatic consumer loss, with cascading consequences for how the rest of the community looks and functions. A few recent case studies suggest that consumer loss leads to increased community variability across space, however it remains unknown how generalizable this pattern is across ecosystems, regions and taxa. Here, we will capitalize on existing data from consumer-exclusion experiments that are common in aquatic and terrestrial ecosystems to evaluate how consumer loss influences community variability across space (i.e., dissimilarity in community composition). We will integrate data from studies at LTERs, the Grazing Exclosure Database, and by searching the literature for data deficient ecosystems (e.g., aquatic, forests). Understanding how consumer loss affects community variability is integral to conservation and management and predicting how an ecosystem will provide services and respond to global change.
2023 Working Groups
LTER: Selection across scales—merging evolutionary biology and community ecology to understand trait shifts in response toenvironmental change
Selection acts on traits at both the community level, determining community assembly, and at the population level, determining the outcome of evolution. Selection at both scales combines with phenotypic plasticity to cause shifts in community-level mean trait values (average species trait values weighted by their relative abundance) in response to environmental change. If selection is typically concordant and populations and communities respond in the same direction, then responses to selection within species will amplify shifts in community mean trait values. In contrast, if selection at population and community scales are not correlated or occur in opposite directions, shifts in community mean trait values will be lower than expected based on shifts in species abundances. Plasticity will influence community-level trait values in similar ways: when plastic shifts parallel/oppose selection, community mean trait value changes will be amplified/reduced. Here, we propose to combine the expansive community composition data from LTER experiments with approaches, ideas, and datasets from evolutionary biology to investigate whether plasticity, selection at the population scale, and selection at the community scale are concordant or discordant. Our framework and findings will help predict long-term shifts in the community-level mean trait values that determine ecosystem functions.
LTER: Fire and Aridland Streams Quantifying Interactive Effects of Fire and Precipitation Regimes on Catchment Biogeochemistry of Aridlands
Increases in the frequency, extent, and severity of wildfires could have long-lasting and wide-ranging effects on hydrology and biogeochemistry of catchments, with consequences for ecosystem services including provision of drinking water. In aridlands, effects of fire will depend on interactions with the precipitation regime, which is also undergoing long-term change toward longer and more severe droughts and more extreme events. This SPARC synthesis group accelerates the ongoing efforts of the Collaborative for Arid Stream Synthesis (CRASS), which has applied data synthesis and time series modeling to test a conceptual model describing interactive effects of fire and precipitation on catchment biogeochemistry. The group has begun synthesis of long-term stream chemistry and discharge records (i.e., LTER, LTREB, USGS, CZO, NEON) for aridlands of the western U.S., where water supplies are particularly vulnerable to changing quality and quantity. Preliminary statistical analyses have quantified interactive effects of fire and precipitation on the timing, severity, and duration of water quality impairment. SPARC funds support an in-person meeting including refining and testing the conceptual model and completion of a manuscript. Ultimately, the group’s goal is to reduce uncertainty in predicting changes to watershed processes and water quality following wildfire in the Anthropocene.
LTER: Producers, Consumers and Disturbance Response of Primary Producers and Primary Consumers to Environmental Change – From small-scale disturbances to seasonal and long-term changes
This LTER SPARC Synthesis Working Group seeks to bring together LTER researchers interested in understanding how disturbances and environmental change across timescales are altering the production and transfer of organic matter from primary producers to herbivores. All ecosystems are subject to temporal variations in biological production and consumption over broad time scales (from diel to decadal) in response to changes in the environment. Understanding the flow of C and energy from primary producers to their consumers provides essential information about ecosystem properties and functions. Both terrestrial and aquatic ecologists have long been assessing ecosystem primary production and the amount of autotrophic C transferred to higher trophic levels, irrespective of how challenging it is to assess these transfer rates. The study of primary producers and consumer interactions is essential to fully understand and predict the ecosystems response to anticipated increased disturbances and environmental changes driven by anthropogenic activities. Together we will synthesize the current status and identify future needs to establish a mechanistic and predictive understanding of the trophic interactions from primary producers to their consumers.
LTER: Do actively cycling C and N pools depend ultimately on soil P supply? Across-biome synthesis
In terrestrial systems the nitrogen cycle is more open than the phosphorus cycle. New N accumulates by biological N fixation and atmospheric deposition, and is readily lost from the system when N is in excess of biological demand. In contrast, available P is supplied from more slowly cycling soil pools already present in the system. Thus, long term rates of ecosystem N accumulation may be constrained by the rate at which available P is provided from stocks of slowly cycling P. In our ASM workshop, we found soil N to be positively correlated with both total and slowly available soil P within each of nine long-term research sites across North America, including six LTER sites. The proposed SPARC will be seeded by members of the ASM workshop and augmented with additional members.
LTER: Pelagic Community Structure Interannual Variability and Long-Term Change in Pelagic Community Structure Across a Latitudinal Gradient
Recent synthesis has shown both similarities and differences in how pelagic marine ecosystems have been influenced by cyclic and long term changes in the marine environment. The pelagic community structure synthesis group uses comparative data to test a series of conceptual models describing how communities respond to stochastic and long‐term change along the latitudinal gradient represented by the four participating LTER sites. Their multipronged team approach employs two major lines of enquiry:
- examining whether patterns & processes discovered in the California Current Ecosystem (CCE) apply to other pelagic sites, and
- exploring whether recently proposed global pelagic community responses apply to the LTER sites, including how such responses are modulated by season and how they may have changed over decadal time frames.
LTER: The Flux Gradient Project Understanding the Methane Sink-Source Capacity of Natural Ecosystems
While biogenic CH4 emissions are thought to be of a similar magnitude to anthropogenic emissions, biogenic emissions remain the most uncertain source of the global CH4 budget. The vast areas with relatively small uptake and emission rates have been largely understudied but could contribute significantly to regional and global budgets. Upland ecosystems can exhibit unexpectedly large annual CH4 fluxes and should not be excluded from observation networks. Yet, current eddy covariance towers measuring CH4 fluxes are biased toward wetlands, and other areas where we expect to observe large fluxes. To improve our understanding of biogenic fluxes, the Flux Gradient Project will utilize infrastructure from the National Ecological Observatory Network (NEON) at co-located LTER-NEON sites to calculate CH4 fluxes. In addition to the fluxes at co-located sites, we will also utilize CH4 fluxes from LTER, Ameriflux and Fluxnet sites.
LTER: Marine Consumer Nutrient Dynamics Consumer-Mediated Nutrient Dynamics of Marine Ecosystems Under the Wake of Global Change
Increases in the frequency and severity of disturbance events as a result of global change are altering population and community dynamics of marine animals. Given that animals are key recyclers of nutrients in many ecosystems, these ecological impacts may have consequences for ecosystem function. Consumer-mediated nutrient dynamics (CND) are anintegral part of biogeochemical cycles, but to-date long-term studies are lacking. Without long-term data across large spatial scales, it is difficult to predict how ecosystems will respond to disturbances. We propose a plan to estimate CND over broad spatiotemporal scales by integrating empirical models of consumer nutrient excretion and egestion with time-series of consumer populations across ten marine and coastal LTER sites.
2021 Working Groups
LTER: Identifying environmental drivers of plant reproduction across LTER sites
Reproduction is a key component of plant life-cycles and is crucial for dispersal, however it has a surprisingly poorly understood relationship to environmental drivers. This is particularly true for plant species with highly variable reproduction over time, known as 'mast seeding'. While mast-seeding patterns have been linked to weather (temperature, precipitation), describing past patterns and predicting future reproduction of plant populations is particularly challenging because of high temporal variability. Using data across Long-Term Ecological Research (LTER) sites, and bringing together experts in mast-seeding, forest ecology, population dynamics, synthesis, and statistical and mathematical modeling, our objectives are to i) assess how generalizable temporal patterns of mast seeding are across species and disparate locations, ii) test how environmental drivers and past performance influence mast seeding along a continuum from non-masting (i.e., low temporal variability) to strongly masting (i.e., high temporal variability) species, and iii) compare statistical approaches for finding environmental drivers for plant reproduction.
LTER: Ecosystem Transitions: Increased Variability and Regime Shifts
Human impacts on ecosystems can result in persistent compositional shifts that are difficult to reverse even after relaxation from perturbations. Considerable debate remains on whether these observed shifts in ecosystems are due to the existence of tipping points and systems with alternative attractors, or whether observed shifts in ecosystems represent communities in alternative trajectories that will eventually reach a common stable point. However, in addition to human perturbations, ecosystems are also experiencing other transient dynamics, like climate variability, which could promote or prevent state shifts. Using cross-site synthesis of LTER experiments that have manipulated human perturbations or climate variability, we will test whether and which observed compositional shifts across the network are a result of critical transitions or transient dynamics. We will use this data to develop and inform theory that will allow us to make and test predictions on the magnitude and frequency of perturbations and climate variability needed to promote or prevent compositional shifts in ecosystems.
2020 Working Groups
LTER:A global synthesis of multi-year drought effects on terrestrial ecosystems
Drought impacts on terrestrial ecosystems have increased globally over the last century with models forecasting that droughts will become more frequent, extreme, and spatially extensive. The goals for this project are to synthesize results from a unique global network of drought manipulations, focusing on how ecosystem productivity responds to drought over time and key mechanisms (changes in plant composition) underlying these impacts. We propose to host a series of working groups to synthesize an existing multi-year dataset from the International Drought Experiment (IDE).
LTER: Ecological Metagenome-derived Reference Genomes and Traits (EMERGENT)
Our climate crisis, resulting from changes in interacting climate variables (temperature, rainfall, atmospheric chemistry) over the last century, has impacted all ecosystems on the surface of the Earth. With modern DNA sequencing techniques it is now possible to simultaneously sample thousands of different species, providing a window into the diverse soil organismal community and their ecological traits. While often the sequence data is stored at international nucleotide sequence data centers (NCBI, EBI, DDBJ), these databases do not have the resources to process and integrate microbiome data. This results in the compartmentalization of studies, failure to effectively utilize data across sites, and repetitive development of similar analytical pipelines across multiple research groups. Our working group proposes to alleviate some of these bottlenecks to make greater use of the existing genetic data to address climate related-questions and provide reference species (genomes) for future research.
LTER: From poles to tropics: A multi-biome synthesis investigating the controls on river Si exports
Riverine exports of silicon (Si) directly influence global carbon (C) cycling through the growth of diatoms, ubiquitous autotrophs in marine and freshwater systems, which account for ~25% of global primary production. Rivers play essential roles in processing and supplying the Si necessary for diatom growth, but we have limited knowledge of the controls on river Si exports,especially how they vary across biomes. Prior work has shown conflicting importance of various drivers, such as lithology, riverine productivity, and terrestrial vegetation in controlling river Si exports. Capturing a baseline understanding of how these factors influence Si exports across biomes is essential for understanding freshwater and marine C cycles, especially during this period of rapid climatic warming.
2017 Working Groups
Synthesizing population and community synchrony to understand drivers of ecological stability across LTER sites
Populations of plants, animals, and microbes fluctuate all the time. Whether populations rise and fall in tandem, independently or alternately can affect ecological stability. Offset fluctuations between species can enhance ecosystem stability. Or alternate fluctuations of the same species in different regions can support species stability. Building on many sources of long-term data, the LTER Synchrony working group aims to understand the drivers and timescales of synchrony and its effect on ecological stability.
Scaling-Up Productivity Responses to Changes in Biodiversity
It seems like a simple question. Does biodiversity loss cause productivity loss? Most experiments to test the question are done on small plots. Scaling up to natural ecosystems introduces complications that could tip the balance toward a stronger—or a weaker—relationship. Drawing on data from biodiversity experiments at multiple LTERs and global observational and experimental networks, the Biodiversity and Productivity working group asks what role time scales, spatial scales, type of experiment, and ecosystem type have on the strength of this key relationship.
Advancing soil organic matter research: Synthesizing multi-scale observations, manipulations & models
This working group is synthesizing soil organic matter data across 15 LTER sites and also includes data and participants from Critical Zone Observatory (CZO) sites, Detrital Input and Removal Treatments (DIRT) Network, and Nutrient Network (NutNET). The group’s goal is to refine and evaluate soil organic matter stabilization theories and to produce a dataset that encompasses the impact of experimental manipulations on soil organic matter at different sites.
2016 Working Groups
Global Patterns in Stream Energy and Nutrient Cycling
The working group will compare stream chemistry data from 19 sites, representing far-ranging biomes including tundra, desert, and tall-grass prairies, as well as boreal, temperate, and tropical rainforests. They aim to identify what factors affect the coupled breakdown and use of carbon and nitrogen in streams. While carbon and nitrogen are inextricably linked, scientists remain stymied by the considerable spatial and temporal variation in the relationships between the two. The unprecedented global database being assembled by the project will allow the team to examine energy and nutrient cycling across seasons and environmental and management gradients.
A Synthesis to Identify How Metacommunity Dynamics Mediate Community Responses to Disturbance Across the Ecosystems Represented in the LTER Network
What factors impact the stability of ecosystems? Previous research has identified dispersal, niche differentiation, and habitat heterogeneity as crucial parameters that determine metacommunity dynamics and stability in response to disturbance. Researchers do not know, however, whether these factors confer stability over long time scales or across ecosystem types. Using LTER datasets, the working group will assess how well these parameters estimate stability across time and space–and in the process, identify the major predictors of metacommunity stability.
Integrating Plant Community and Ecosystem Responses to Chronic Global Change Drivers: Toward an Explanation of Patterns and Improved Global Predictions
Many global change drivers (GCDs) lead to chronic alterations in resource availability, and scientists anticipate that the magnitude and direction of ecosystem responses to these changes will be non-linear. To predict responses to GCDs across a wide variety of ecosystems, the working group will take advantage of 101 similar experiments done across 17 LTER sites, all of which have examined plant community responses to changes in resource availability. The group aims to discover whether changes in plant community structure, productivity, and carbon storage are predictive of shifts in ecosystem function.
