Organized Oral Sessions
Designing, restoring, and managing ecosystems
Monday, August 7, 8-11:30 am
Organizers: Marty Matlock, W. Cully Hession
The need for competent ecosystem design, restoration, and management criteria and methods is great, as articulated by the ESA Visions Committee. This session is organized to explore the breadth and depth of ecosystem design, restoration, and management practices. Specific questions to be addressed include: 1) How much and what in ecological knowledge base is appropriate for application in design, restoration, and management of ecosystems; 2) What are the greatest challenges in applying ecological knowledge for design, restoration, and management of ecosystems; 3) What criteria can we establish now as governing principles in ecosystem design; 4) What criteria can we establish now as governing principles in ecosystem restoration; 5) What criteria can we establish now as governing principles in ecosystem management; 6) What authority/oversight role will ESA play in establishing these criteria; 7) What role should public engagement play in developing and implementing ecosystem design, restoration, and management projects/criteria; and 8) How should the public be engaged in developing and implementing ecosystem design, restoration, and management projects/criteria?
Alteration of North American forest communities by invasive invertebrates
Monday, August 7, 8-11:30 am
Organizers: Lee Frelich, David Foster
Invasive invertebrates as a group are altering temperate hardwood and conifer forests of eastern North America on a massive scale. Eastern hemlock, a foundation tree species, is disappearing from Connecticut to North Carolina due to the introduced hemlock wooley adelgid, several species of ash are threatened by the emerald ash borer, European earthworms have infested several million hectares of forest and changed soil nutrient cycling and water status, and exotic selective herbivores such as gypsy moths and European slugs are altering the species composition of plant communities. This organized oral session will provide a broad survey and synthesis of invasive insects, earthworms, and slugs that collectively threaten to remove entire tree species from the forests of eastern North America, put the remaining species through the filter of selective herbivory, and re-engineer ecosystems by changing soil structure, nutrient cycling, water flow, and seedbed properties. These changes brought about by invasive invertebrates are occurring (or will shortly occur) within our most treasured parks, natural areas, and designated wilderness areas (e.g., Great Smoky Mountains National Park , Boundary Waters Canoe Area Wilderness). This group of invaders will both illuminate ecosystem function by altering fundamental resource gradients and species composition on large scales and force us as ecologists to grasp for new conservation strategies. Case studies of impacts by several invasive invertebrates will be presented, along with paleoecological perspectives on forest response to past loss of tree species, modeling the spread of invasive insects and susceptibility of plant communities to invasion, and policy and biological strategies for managing these invasions.
Functional roles of fine roots and mycorrhizal fungi in carbon and nutrient cycling
Tuesday, August 8, 8-11:30 am
Organizers: Erik Hobbie, John Hobbie
Fine roots and mycorrhizal fungi are primary pathways for nutrient uptake by plants and are important sinks for carbon acquired in photosynthesis. Quantification of carbon and nutrient cycling driven by fine roots and mycorrhizal fungi is difficult for several reasons including the fine-scale heterogeneity of soil, uncertainties in turnover rates of fine roots and fungal hyphae, and potential pitfalls in extrapolating from laboratory studies to the field. To circumvent these difficulties, several methods have been employed to estimate belowground carbon allocation: mycorrhizal allocation, root allocation, nutrient uptake, and fungal and root turnover. Promising methods include in-growth cores, carbon flux budgets, girdling or chilling trees to restrict belowground allocation, mapping mycorrhizal and nutrient heterogeneity in soil, and using the natural abundance of 14 C and 15 N. Our goal is to advance understanding of the strengths and limitations of these methods through presentations and discussion.
The modern paradigm in population ecology: stochastic, statistical, and inferential
Tuesday, August 8, 8-11:30 am
Organizers: Elizabeth Holmes, Chris Jordan, Brian Dennis
In the last 10 years, the study of population and community dynamics has shifted towards stochastic models away from the deterministic models so familiar in ecology during the last century. Understanding of the properties of stochastic versions of familiar ecological models is an active area of research and, along the way, the field of theoretical ecology is shifting to new paradigms of thinking about ecological processes. The familiar concept of population state or carrying capacity as a fixed line passing through a series of observations is not particularly meaningful in a stochastic framework and is replaced by the concept of stationary probability distributions. The concept of equilibria is replaced by the concepts of inflection points in first passage probabilities and modes and antimodes in stationary distributions. At the same time, there has been a fundamental shift away from qualitative visual comparisons of model output with qualitative system behavior and towards rigorous statistical linking of stochastic ecological models and observations using modern, often numerical, statistical methods that are suited for non-linear stochastic models which include both process and non-process variability. Concepts such as likelihood surfaces, first passage distributions, conditional probability distributions, prior and posterior distributions, numerical statistical algorithms, and formal model support have joined nonlinear dynamics and stability as permanent parts of the landscape of ecological understanding. This session features some of the contemporary research on stochastic ecological dynamics and estimation that is changing the face of population ecology and that will ultimately fundamentally change the way we think and make inferences about ecological processes.
Climate change and timing in ecological communities
Tuesday, August 8, 1:30-5 pm
Organizers: Abraham Miller-Rushing, Richard Primack, David Inouye
Global climate change has the potential to alter and disrupt ecological communities. Among the most important and dramatic ecological changes are changes in phenology, i.e., the timing of climate-sensitive ecological events. Changes in phenological events could disrupt close ecological relationships, such as leaf-out, insect emergence, pollination, fruit dispersal, and the feeding behavior and breeding success of birds. These changes will also affect critical ecosystem functions, such as carbon sequestration, productivity, and water availability. In this session we will hear evidence of phenological changes, mostly involving plants, that are already occurring as a result of climate change. We will learn about new techniques that are available to monitor these changes, such as remote sensing and multi-continental networks of ground observations. Lastly, we will hear predictions of how time-sensitive ecological relationships will change in response to climate change. Climate change is already affecting ecological systems and will continue to do so over the coming years, providing a particularly relevant topic for this session.
Ecology and poverty alleviation: bringing ecological knowledge to the forefront of development goals
Tuesday, August 8, 1:30-5 pm
Organizers: Fabrice De Clerck, Cristina Rumbaitis del Rio , Jane Carter Ingram
Globally, 1.2 billion people live on less than $1 per day. This population is highly dependent on natural resources for daily survival, whether they live in rural or urban areas. Often the poorest are the most vulnerable to degradation of natural resources, loss of ecosystem services, and natural disasters. Thus, ecologists have a distinct role to play in the alleviation of global poverty. At the Montreal ESA Meeting, more than 50 ecologists gathered at a discussion session to identify specific ways in which ecology can be used in poverty alleviation. It was clear that ecologists are needed to “paint the big picture.” The tradition of elucidating complex systems and relationships and working across scales and disciplines enables ecologists to tackle the similarly complex, multi-faceted problems of poverty reduction. Much of the ecological knowledge needed to address the challenges of poverty is already known; we must focus on information needs and exchange and applying knowledge in the appropriate social and ecological contexts. The main obstacle to the use of ecology in poverty reduction is that sustainability is often treated as an afterthought in development projects. It is understandable that ecological sustainability is overlooked when primary development goals focus on such basic issues as eliminating hunger, eradicating HIV, and providing universal access to safe drinking water. However, as ecologists we must make the case that ecological sustainability is neither simply a benefit of development interventions nor an impediment to development. Rather, ecological sustainability is a means to achieving poverty alleviation goals; the foundation of a healthy society is a healthy environment. The goals of this oral session are: 1) to present examples of the application of ecological principles and knowledge to poverty reduction strategies; 2) to synthesize information from recent environment and development initiatives, assessments, and meetings; and 3) to engage in a discussion of the challenges and opportunities that arise from using ecological sustainability as means to alleviate poverty.
When does fear matter? A road map to the implications of trait-mediated effects to ecology
Wednesday, August 9, 8-11:30 am
Organizers: Evan Preisser, Geoffrey Trussell, Earl Werner
Predators eat prey and prey try to avoid being eaten; this statement embodies both classical (predators affect prey populations via consumption) and more recent (predator avoidance may itself incur significant costs to prey populations) approaches to community ecology. Traditional models have emphasized consumptive or density effects to predator-prey interactions but recent work has indicated that community dynamics are strongly influenced by the effects of non-lethal interactions between predators and their prey. Although ecologists are often aware of the potential importance of prey responses to predation risk (‘trait-mediated effects'), these effects are rarely explicitly incorporated into studies because of the difficulty of disentangling the role of trait-mediated and density-mediated effects. The influence of non-lethal effects on prey growth, life history, and resource use can reinforce or oppose density-mediated effects, making the outcome of such interactions difficult to predict. This symposium synthesizes theory and empirical research to explore the factors influencing the relative importance of trait- and density-mediated effects in ecological communities. We seek to provide a ‘road map' that details when and where researchers need to account for such effects and identifies the potential mechanisms driving these effects in each case. We address how trait-mediated effects may fundamentally change our approach to issues such as the impact of invasive versus native predators, the effect of consumers on diversity-functioning relationships, and the use of trophic cascade theory for managing natural communities. Other presentations will explore the implications of trait-mediated effects to spatial ecology and theoretical developments and how these effects ‘scale up' as more species are added to a community. We conclude with a round-table discussion on gaps in our knowledge base and suggested directions for theoretical and empirical research.
Niche verses neutral: a look at an iconic idea in community ecology, its challenger, and the middle ground, Part II
Wednesday, August 9, 1:30-5 pm
Organizers: Annette Ostling, Nathan Sanders, Jeffrey Lake
This session is a continuation of the symposia with the same name. Throughout the 20th century, the dominant view in ecology has been that species live together in communities only when they have different “niches”; an even slightly better competitor for a niche will drive other species to extinction. The alternative notion—that chance dominates over competitive exclusion to shape communities—has lacked an adequate quantitative formulation. In the 1970's and 80's, random “null models” were pitted against niche-based “assembly rules”, but these were criticized as not incorporating the effects of demographic stochasticity, evolutionary history, and dispersal limitation. More recently, a “neutral theory” of biodiversity has been proposed that incorporates many of these effects. At the same time, ecologists' understanding of the niche and the evolutionary processes leading to it has become more sophisticated. In this symposium and the organized oral session following it, we will take stock of what we have learned about community assembly in the past 30 years. We will explore the debate between an idea so established it has become an icon and the latest version of the upstart notion challenging it. We will focus on the middle ground, where researchers are sorting out when the different forces of community assembly dominate and discovering phenomena arising from the combined action of niches and chance.
The devil is in the detail: theory for empirical model systems
Thursday, August 10, 8-11:30 am
Organizers: Ottar Bjornstad, Priyanga Amarasekare
The foundational theory of ecology, epidemiology and behavioral ecology has been taught to every undergraduate and graduate student during the last half century. The underlying models have also motivated numerous historical and recent experiments and detailed observations on particular empirical systems. Encouragingly, the classic strategic models, many of which date back to the 1920s through 1960s, offer qualitative predictions that match data. However, many of the recent strides forwards in theoretical ecology have come from very specific case studies involving clever experimentation and/or detailed field studies. This symposium will: 1) explore the utility of the foundational models in understanding the ecological dynamics of specific systems; and 2) discuss how many recent conceptual and theoretical insights have been reached by embracing the 'idiosyncrasies' of any particular system. The individual presentations detail these issues using case studies from behavior, biocontrol, epidemiology, and community ecology.
Rhizosphere functioning in carbon and nitrogen cycles
Thursday, August 10, 8-11:30 am
Organizers: Wendy Silk, Gretchen North
A boundary layer of soil surrounding plant roots is the “rhizosphere,” the site of complex ecological interactions among roots, soil particles, microbes, and insects. It has long been known that a large fraction of carbon recently fixed in leaves is rapidly (on the time scale of minutes to hours) released to the rhizosphere. Release of carbon from living roots is only part of the complex carbon cycle. Myriad processes interact to produce carbon sequestration in soils and carbon flux to the atmosphere. Root death is an important source of soil carbon, as is microbial activity. Bacteria and fungi degrade the root exudates, and the associated soil respiration competes with microbial mineralization of the available carbon. Recent discoveries from a number of laboratories are revealing mechanisms of transport processes coupled with complex chemical signaling among the biotic components of the rhizosphere. Many questions need to be addressed in order to understand biogeochemical cycles in soil and the crucial role of the rhizosphere. For example, how is the rhizosphere organized spatially and temporally, and how can we characterize the effects of environmental perturbation on its structure? What are the rates of fine root production and death? How do older parts of roots affect their rhizospheres? What is the role of rhizosphere moisture in stimulating carbon and nitrogen deposition and root decomposition? What is the capacity of soil to store carbon? Thus, rhizosphere studies are of fundamental importance to ecology on spatial scales ranging from the microbial to the global. In the spirit of the “upstart and icon” theme of the Memphis meeting, we are featuring talks by graduate students as well as professors.
Bottomland hardwood forest restoration and management for wildlife
Thursday, August 10, 1:30-5 pm
Organizers: Randy Wilson, Daniel Twedt
Hardwood forests within river floodplains provide a myriad of ecological benefits: flood abatement, enhanced water quality, carbon sequestration, wildlife habitat, and merchantable forest products. Throughout the world, and specifically within the southeastern United States , millions of hectares of forested wetlands have been converted to agriculture but financial incentives, combined with marginal profitability of farming these converted forest lands, have induced widespread restoration of bottomland forests. In the Mississippi Alluvial Valley , approx. 200,000 ha have been planted with hardwood trees with an additional 200,000 ha expected to be restored during the next 10 years. Success of restoration has varied among sites, but creating and sustaining full ecological benefits of these bottomland hardwood forests is conditioned upon appropriate restoration and management. Wildlife habitat on restored and extant forested wetlands is influenced by their landscape placement, vegetative conditions, and the temporal status of habitat manipulations (restoration or management). Recently, restoration techniques have been developed that hasten colonization by silvicolous wildlife. Additionally, silvicultural management that promotes sustainable desired forest conditions within extant forested wetlands has been embraced by the conservation community. In this session, we present an assessment of wildlife response to bottomland restoration and management.
Ecological stoichiometry of terrestrial animals
Thursday, August 10, 1:30-5 pm
Organizers: Adam Kay, Susan Bertram, John Schade
Ecological stoichiometry, the study of element balance in ecological systems, provides a framework for linking biochemical characteristics of organisms to ecosystem processes. A key nexus of integration in this framework is the balance of elements in organisms, which can reflect a consumer's physiological characteristics and life history attributes, its potential for growth limitation under nutrient scarcity, its impact on lower trophic levels, and the relative rate at which it retains ingested materials. These linkages are mechanisms by which individual-level attributes can influence population and community dynamics, food web structure, and the biogeochemical cycling of nutrients. Although the ecological relevance of element balance is firmly established in autotrophs and aquatic consumers, research on terrestrial animals has instead been based primarily on models using energetic or demographic currencies. As a result, there is still relatively little known about the degree, causes, or ecological consequences of taxonomic- and environmentally-induced differences in elemental composition among terrestrial animals. Speakers in this session represent a variety of disciplines and approaches that extend from physiological to ecological to ecosystem-level analyses. As a result, talks will highlight the importance of animal stoichiometry for processes at multiple levels of biological organization. Our goals are: 1) to illustrate how a focus on elemental composition in animals can reveal novel resource-based influences on ecological interactions; and 2) to encourage the application of ecological stoichiometry to systems and resource questions previously studied in a single-resource framework.
Phenology and ecosystem processes
Friday, August 11, 8-11:30 am
Organizer: Asko Noormets
Vegetation phenology provides an integrative measure for quantifying the season-dependent shifts in ecosystem processes. It offers the promise of reducing uncertainty in quantitative assessments of ecosystem carbon and water cycles associated with the variation in growing season length. Understanding the phenological signals that correlate with different processes would allow: 1) the use of remote sensing technology to continuously monitor these changes; and 2) the application of remotely sensed information to improve the predictive capabilities of regional biogeochemical models. This session addresses the application of phenology for interpreting variations in ecosystem function and covers the following aspects: 1) phenological changes and fluxes of carbon, water, and energy; 2) feedbacks between surface phenology and atmospheric boundary layer processes; 3) use of remote sensing for continuous monitoring of phenological change; and 4) incorporating phenological information in regional biogeochemical models.
Application of behavioral principles for ecosystem stewardship
Friday, August 11, 8-11:30 am
Organizers: Mark Brunson, Fred Provenza
Ecology has contributed greatly to the conservation and restoration of managed ecosystems such as forests and rangelands by informing the design of management strategies that reflect our current understanding of processes and conditions of the abiotic and vegetation components of ecosystems. Less attention has been given to behavioral ecology and the interactions of animals and microorganisms within ecosystems. This session addresses how new ideas about behavior can be applied to improve ecosystem stewardship. If one assumes animal behavior is fixed in the genome, then improvements in vegetation or abiotic condition generally require removal of species (especially non-native or domestic animals) whose behaviors are associated with ecosystem degradation. This session will highlight research demonstrating that animal behavior is more plastic than traditionally thought—determined by learning as well as genome—and will describe how ecosystem managers have been able to take advantage of, and even influence, behaviors of both domestic and wild animals in order to achieve desired stewardship outcomes.