Breakout sessions from the Science Council meetings often evolve into synthesis working groups. The 2016 meeting was no exception, with a lively and challenging series of discussions resulting in six potential synthesis groups. If any of the descriptions below pique your interest, please follow up with the designated lead scientist or correspondent.
How Do Abiotic Factors Affect Species Interactions?
Participants: Steven Pennings (corresponding), Anne Giblin, Anthony Joern, Chris Ray
Species interactions are often context dependent. For example, the well-studied Stress-Gradient Hypothesis suggests that species interactions among primary space-holding organisms (plants and sessile invertebrates) switch from negative at low stress to positive at high stress. There is also theory for how trophic interactions should be affected by abiotic stress, but it has opposite predictions in marine habitats (stress reduces consumer effects) and terrestrial communities (stress increases consumer effects), probably because the best-studied stress in terrestrial habitats (drought) affects plants more than consumers. Because LTER includes both aquatic and terrestrial habitats, we can integrate these perspectives. However, our group doubted that we had appropriate existing data to conduct a powerful synthesis.
An alternative would be a distributed experiment (similar to NutNet) in which a simple, low-cost measurement of consumer pressure would be conducted at multiple sites for several years (hoping to capture years that varied significantly in “stress”). It might also be possible to do the experiment across micro-habitats that vary in stress within a single year, or to conduct short-term experiments (lasting, say, 2 weeks) that took advantage of varying stress within a single year. The path forward would be to convene a working group that would work out the details of methodologies and specific hypotheses, and then seek funding for organizational and data management costs. We do not currently have the critical mass to move forward, but Steve Pennings (spennings@uh.edu) is happy to receive names of parties that might be interested, and will send a follow-up email to this list later in the summer.
Global Change Conceptual Paper
Participants: Peter Groffman (lead), Lihini Aluwihare, Matt Betts, Hugh Ducklow, Michael Gooseff, Sally Holbrook, Rhett Jackson, Sherri Johnson, Marcy Litvak, Michael Nelson, Mark Ohman, Michael Pace, Dan Reed, Emma Rosi-Marshall, Gaius Shaver, Emily Stanley
What does LTER science tell us about what each of our ecosystems will look like in the future? Every site in the LTER network has stories about long-term changes in species linked to global change. What can we learn from these stories? What can we learn about the value of long versus short-term data? We envision a conceptual paper that collects stories that demonstrate clear shifts due to climate change in long-term data, as well as others that show how long-term data can reveal when changes that appear linked to climate change are, in fact, not. We will be putting together some examples of exactly what we are looking for before asking around to the wider network to submit your own examples.
Global Change Synthesis Working Group Opportunity
Participants: Matt Betts, Jarrett Byrnes, Shannon LeDeau, Bob Coopper
How do shifts in the mean and variance of climate stresses push communities along an axis of specialization? Changes in both the long-term mean and variance of climate stresses are likely to shift community structure. Recent predictive frameworks hypothesize that shifts in one or both should favor species that are generalists with respect to diet, habitat use, and overall niche breadth. We propose to assemble a working group to use the unique time series of stress measurements and vast taxonomic breadth across LTERs – from reefs to tundras – to test these hypotheses. We are looking for interested collaborators at any career stage to help us begin scoping the project to submit to for the next NCEAS LTER RFP in the fall.
Phenology
Participants: Dawn Browning (lead, JRN), Christie Bahlai (KBS), Jess Zimmerman (LUQ), Sherri Johnson and/or Mark Schulze (AND), others….
The phenology breakout group set out to characterize seasonal dynamics (i.e., plant phenology) using the 38 phenocams located at 11 LTER sites. Phenocams can identify seasonal metrics such as start, end, peak, and timing of peak of season. The distribution of cameras allows detection of differences due to physical (i.e., topography) and anthropogenic factors (i.e., land use).
The group explored the potential for observing relationships between these high-frequency data sets and other datasets associated with populations such as the rich multi-taxa long-term record of LTER sites. Their working hypothesis is that seasonal changes in vegetation captured by phenocams can serve as an integrative metric for seasonal patterns in other taxa.
Data sets:
- Growing season metrics (start, end, length of growing season, date of peak green) derived from 34 phenocams at LTER sites. Data as of 5/19/16 spans 76 camera years across 11 LTER sites. Camera record ranges from 1 to 7.5 growing seasons.
- Are investigating the availability of phenology-related datasets at LTER sites to include plant and animal phenology records. PLEASE send name and email to Dawn (at dawn.browning@ars.usda.gov for phenology-relevant contact at your LTER site.
- MODIS NDVI time series for each camera location to examine the relationship between gcc (from phenocams) with NDVI from satellite to determine whether or not NDVI can be used to expand the growing season record.
Next steps:
- Develop or revise regions of interest (ROIs) for cameras
- Connect with potential collaborators (each site represented)
- Update phenology data availability in the network (building on 2007 white paper by Henebry et al.)
- Develop a timeline…in progress
Invasive Species Effects on Community Function
Participants: Jake Walsh (NTL, lead), Jennifer Fraterrigo (CWT), Steve Hamilton (KBS), Gary Lovett (HBR), Karen McGlathery (VCR), Bob Miller (SBC)
Invasive species are a key driver of global environmental change, yet LTER has not fully taken advantage of opportunities to perform cutting edge synthesis in invasion ecology. In 2012, an LTER working group led by Alex Latzka and Ali Mikulyuk (NTL) proposed investigating the long-term population dynamics and trajectories of invasive species in the LTER network.
This work addressed a fundamental concept in invasion ecology that, to this day, has not been addressed in synthesis. However, the work was not funded. Latzka has since participated in the Berlin Invasive Species Dynamics Network (InDyNet – a network dedicated to gathering and synthesizing global invasive species data) led by Jonathan Jeschke (Professor at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries). However, he is looking to hand off the project, hopefully to an LTER scientist as InDyNet has expressed great interest in LTER continuing its presence at InDyNet meetings. In particular, InDyNet extended an expenses-paid invitation to Latzka and Walsh for their 2nd meeting this upcoming November in Berlin.
Our working group discussed a wide range of potential research directions that would allow LTER to leverage its strengths (e.g., long-term data, deep site knowledge and expertise, ecosystem-scale data, and sites located across a wide range of biomes) to address key issues in invasion ecology. Much of our focus was on investigating the effects and impacts of invasive species in the long-term, and grounding our analyses in hypotheses.
We would likely propose a working group with two primary goals, working in concert with Jonathan Jeschke and InDyNet:
- Complete analysis and publish on the long-term dynamics of invasive populations. This is a surprisingly under-developed area of invasion ecology, but it is basic and critical to understanding invasions and their long-term effects on ecosystems.
- For example: Dave Strayer is leading an InDyNet publication empirically testing the “boom-bust” dynamic commonly reported for invasions. The common perception that invasive species will decline with time affects how we manage, or don’t manage, invasions. The results of that manuscript reveal the importance of empirically investigating population dynamics to better understand and manage invasions.
- This proposed work would include analysis of boom-bust dynamics as well as many other possible trajectories, such as prolonged lags, cycles, long-term declines/increases, stability, etc.
- There have likely been developments in invasive populations at LTER sites since 2012 (e.g., spiny water flea has become a key focus at NTL). A brief survey of LTER sites may help update and build the dataset.
- Investigate the long-term effects and impacts of invasive populations.
- We propose a framework nested in the abundance trajectory work above, as well as deeper investigation into the drivers of invasive species’ short-term (pre/post, impact at high initial densities, etc.) and longer-term effects.
- LTER site data and expertise will be critical and we will be surveying and following up with LTER site data managers and/or PIs.
It would be interesting to expand this work into case studies of the several invasive species removals conducted in the LTER network. This is where we could involve other agencies in the project as LTER only has a handful of removal efforts.
‘Landscape of Fear’: How Non-consumptive Effects of Predators Influence Ecological Processes Across Multiple Scales
Participants: J.S. Kominoski, L. Deegan, K. Kielland, J. Nelson, R. Rehage, R. Ruess, R. Schmitt
Global declines in large predators are changing direct and indirect trophic interactions across diverse ecosystems. Although direct effects of predator declines on ecosystem structure and function are well characterized in certain ecosystems, we lack a mechanistic understanding of how non-consumptive effects of predators on prey behavior (termed the landscape of fear) propagate across hierarchical scales of ecological pattern and process. Specifically, we focus on how such non-consumptive effects influence herbivore movements, distributions, and feeding behavior to impact processes beyond the level of individuals and populations, to influence vegetation composition, successional pathways, ecosystem dynamics, and landscape heterogeneity. Our primary objective is to develop a conceptual paper for what these effects would look like based on long term datasets. We will use examples from LTER and non-LTER sites to illustrate how knowledge gained from long-term data has led to enhanced understanding of such indirect effects of predators on shaping landscape structure and function and how to guide detection and tracking of these effects in long term datasets.
We will address the following questions:
- How do non-consumptive predator effects influence herbivore habitat and forage selection?
- How do these effects impact plant and animal community interactions, population dynamics, ecosystem function, and landscape structure and heterogeneity?
- How do alterations in trophic structure and the ‘landscape of fear’ influence ecosystem response to environmental change?
