With over 40 years of continuous data collection across many biomes, the Long Term Ecological Research (LTER) Network is a rich source of information for testing big-picture concepts about how ecosystems work. Luckily, the Network also brings together a group of scientists with creative ideas about how to wring new insights from diverse data sources.
The LTER synthesis working group process is designed to capitalize on the experiments, contextual knowledge, data, and creativity of the LTER Network. By funding small groups of scientists from inside and outside the Network to work intensely together on a synthesis project, the process encourages the ecological community to use existing data to probe novel theories, test generality, and search for gaps in our understanding.
The active Synthesis Working Groups are listed below.
Principal Investigator: David Hoover, Olivia Hajek
Award Date: August 20, 2024
Description:
Assessing the resilience of productivity to climate variability across management and climate gradients
The patterns and drivers of primary production are the foundation of ecosystems and food webs worldwide, and the products of primary production drive global carbon cycling and provide food and other key resources to people. Few studies that compare the patterns and drivers of primary production across multiple ecosystems, however, focus on managed ecosystems (e.g., rangelands, croplands), even though managed ecosystems are the predominant type across the globe. This synthesis group supplements natural ecosystem data from the LTER with data from two other prominent research networks—the Nutrient Network (NutNet) and the Long-Term Agricultural Research Network (LTAR)—to examine how management status and climate affect the resilience of primary production. The diverse working group has expertise in resilience theory, climate change, ecosystem ecology, and sustainable agriculture, spanning a variety of career stages and institutions. Results from this effort are important for land use decisions and global carbon cycle modeling.
Principal Investigator: Jamie McDevitt-Irwin, Kelly Speare, Sally Koerner
Award Date: August 21, 2024
Description:
Consumer Absence Generates Ecological Dissimilarity (CAGED): A cross-ecosystem synthesis exploring the consequences of consumer loss on community variability
Consumers are disappearing from ecosystems across the globe, the effects of which influence how the remaining community looks and functions. Recent case studies suggest that consumer loss leads to increased community variability across space. However, it remains unknown if this is a general pattern shared across ecosystems, regions, and taxa. This working group 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). The project will combine seventy-five exclusion experiment datasets from studies at LTERs, the Grazing Exclosure Database, and other 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.
Principal Investigator: Mackenzie White, Graduate Student, FIU, Bradley Strickland, Postdoctoral Research Associate, VIMS, Jennifer Rehage, Associate Professor, FIU, Deron Burkepile, Professor, UC Santa Barbara,
Award Date: January 10, 2023
Description:
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 an integral 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. The synthesis group plans 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. They will address two main objectives:
- characterizing spatiotemporal patterns in the magnitude and variability of CND and;
- evaluating the resilience of CND to variable disturbance events.
This is a revised proposal based on positive feedback of the group's 2018 submission and input from colleagues during a cross-site workshop at the 2022 LTER ASM. With funds from LTER LNO, this diverse working group will synthesize LTER data to improve understanding of CND over broad spatiotemporal scales under the wake of global change.
Principal Investigator: Russell R Hopcroft, Professor, University of Alaska Fairbanks, rrhopcroft@alaska.edu, Mark Ohman, Professor, Scripps Institution of Oceanography, Heidi Sosik, Senior Scientist, Woods Hole Oceanographic Institution, Oscar Schofield, Professor, Rutgers University
Award Date: January 10, 2023
Description:
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.
Principal Investigator: Sparkle L. Malone, Assistant Professor, Yale University, Jackie H. Matthes, Senior Scientist, Harvard University
Award Date: January 10, 2023
Description:
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. We hypothesize that upland ecosystems will fluctuate from being a sink to a source depending on moisture conditions. Quantifying the CH4 budget of natural ecosystems is important for assessing realistic pathways to mitigate climate change, because uncertainties in the magnitude, size, and location of sources and sinks are currently limiting budget development.
