The deadline for submitting an oral or poster presentation is 5:00 pm EST, Thursday February 27. Abstracts can be submitted here.
A full list of organized oral sessions can be reviewed here. Sessions of potential interest to Novus participants are listed below.
Advancing Knowledge of Alpine and Arctic Treeline Ecotones and Responses to Environmental Change
Organizer: Lara Kueppers, University of California Merced
Treeline research has been advancing rapidly, motivated in part by the need to predict land surface feedbacks to regional and global climate change, water resources in mountain regions, and impacts of environmental change on high latitude and high elevation biodiversity. Upper elevation and northern treeline ecotones are boundary zones between forest and arctic or alpine treeless zones. Although presence of upright trees has defined the treeline per se, treeline is more accurately described as an ecotone structured by complex interactions among vegetation, soils, animals, climate, snow, topography, and disturbance regimes. Responses of this ecotone to environmental change have been observed, but complex lags and feedbacks — in addition to topographic influences that confound of responses in mountain treelines — challenge predictions of change. This session brings together diverse perspectives and expertise in treeline research to report recent advances, both in basic understanding of treeline dynamics and in predicting responses of alpine and arctic treelines to environmental change. By including talks from diverse subfields in ecology the session seeks to foster new collaborations and insights that will advance integrative science of the treeline ecotone. A further objective is to bridge the historical divide between arctic and alpine treeline research. The session comprises ten talks on different aspects of treeline research: paleoclimate and paleoecology, tree demography, ecophysiology, modeling treeline, plant-animal interactions, experimental ecology, ecosystem processes, and the role of disturbance in structuring treeline. Speakers represent the international nature of treeline research and work in both arctic and alpine treeline ecotones.
Climate Warming, Changing Disturbance Regimes, and Forest Resilience
Organizer: Jill F. Johnstone, University of Saskatchewan
The frequency, severity, and extent of natural disturbances are changing profoundly as climate continues to warm, and these changes pose serious challenges to scientists, land managers, and society. How forest ecosystems will respond to novel disturbance regimes interacting with warmer climate is poorly understood but incredibly important to anticipate. Observations of past forest change and predictions from ecological theory suggest that, against a backdrop of changing environmental conditions, disturbances can trigger rapid change in forest ecosystems. Novel disturbance regimes may disrupt forest ecosystems and the processes that maintain them, and initiate new pathways of change by affecting post-disturbance community assembly and succession. Furthermore, changes to one disturbance regime may alter the likelihood or severity of another (i.e., linked disturbances) or produce compound disturbances that alter ecosystem resilience (i.e., the capacity of the system to recover following disturbance). The combination of changing climate conditions, altered disturbance regimes, and sensitivity of successional pathways to initial conditions creates a strong potential for rapid and non-linear shifts in forest ecosystem states. The aim of this session is to explore the mechanisms, dynamics, and implications of disturbance-mediated changes in forest resilience across different forest ecosystems. Presentations will tackle questions such as: What is the role of climate change in altering disturbance regimes and post-disturbance ecosystem recovery? How do disturbances interact across forest landscapes? What are the key thresholds, non-linearities, or leverage points in forest system dynamics? Under what conditions do disturbances trigger state changes in forest ecosystems? Examples will be drawn from a range of forests with an emphasis on northern and temperate forests of North America. We aim to identify commonalities that may lead to a more explicit framework for anticipating and managing forest state changes likely to occur with continued climate warming. The set of presentations will begin with an overview of disturbance dynamics and climate change, followed by presentations that address complementary topics that explore the nature of changing disturbance regimes, altered successional trajectories, and mechanisms that may underpin qualitative changes in forest landscapes. The session will conclude with perspectives on how our understanding of forest responses to changing disturbance regimes should influence our strategies of forest management. As the evidence for changing disturbance regimes accumulates around the globe, it is timely and important for us to consider how we can best anticipate the potentially dramatic impacts on forest ecosystems.
From Bacteria To The Biosphere: Nitrogen Isotope Applications Across Systems And Scales
Organizer: Alison R. Marklein, University of California – Davis
The ratio of heavy to light nitrogen isotopes can be used to examine the N cycle, across scale ranging from bacteria to the global ecological system. The fact that the 15N:14N ratio changes based on rates of biological activity can be used to infer biological processes that are otherwise difficult to measure. We propose a session to address the past, present and future applications of nitrogen isotopes in ecological research. The proposed session will begin with an overview of nitrogen isotopes, will be followed by talks focusing on specific ecosystems, and then focusing on different time periods. Speakers discuss research in terrestrial, oceanic, and land/aquatic interfaces, paleo reconstruction using nitrogen isotopes, and modeling applications.
Understanding Climate, Disturbance, and Forest Dynamics From Regional to Individual Tree Scales in the Sierra NevadaOrganizer: Matthew D. Hurteau, Pennsylvania State University
Changing climate and a legacy of past land-use interactively influence forest dynamics. Climatic influences on wildfire and forest productivity have the potential to alter forest distribution, composition, structure, and function at regional to individual tree spatial scales. Changes in disturbance regimes and forest productivity alter the biophysical and biogeochemical properties of forest systems, which in turn can feedback on climate. Understanding the relationship between climate, disturbance, and forest dynamics requires regional to individual tree scale investigation to capture both top-down and bottom-up effects. Furthermore, understanding these relations at multiple spatial scales is important to understand how current and future forest management will impact forest dynamics and climate feedbacks going forward. The goal of this session is to present research on the effects of climate and ecosystem processes on forest systems across multiple spatial scales. This session will include speakers who use a range of approaches (e.g. empirical studies, statistical and simulation modeling) to investigate how climate, disturbance, and management influence forest dynamics. This session will provide a venue for examining the range of approaches and questions asked as they pertain to forest systems. The anticipated structure of the session includes regional simulations of climate effects on fire probability, regional simulations of climate effects on forest productivity and its interaction with insects and fire, stand to regional scale effects of the interaction between fire and forest restoration efforts, stand-scale above and belowground carbon dynamics with fire, and climate effects on species-level productivity and regeneration. This session will be of interest to a broad range of ecologists working in forest systems, as the research topics covered are relevant to many forest types. Furthermore, many of the speakers will present cutting-edge work that is dealing with the scale disparity present when investigating both top-down and bottom-up controls on forest dynamics.
Understanding the Structure and Function of Fire Maintain Ecosystems: Honoring the Research Influences of Dr. Robert Mitchell
Organizer: Gregory Starr, University of Alabama
Frequent low-intensity fires maintain the structure and function of ecosystems with an evolutionary history of chronic fires whereas fire suppression transforms the structure and modifies the function. Fires burn as much as 4 million km2 globally and release as much as 2-3 Pg of C annually, effecting ecosystem to global carbon dynamics. Fire also influences carbon dynamics by altering the structure of the above- and belowground allocation and investment of plant C due to changes in life form (woody trees and shrubs versus grasses). These structural ecosystem changes lead to functional alteration, such as reduction in C4 carbon fixation. While climate, particularly temperature and moisture, sets limits on the distribution and productivity of the world’s biomes, fire resets systems far from their physiognomic limits. Fire’s impact is fully expressed in humid grasslands and savannas; if fire is suppressed, vegetative structure moves from a C3/C4 savanna to closed canopy shrubland, causing a concomitant loss of biodiversity. Future suppression could extend the global area of closed canopy shrub/forest lands from 27% to 56% and have subsequent consequences on biodiversity. The influence that fire—or the lack of fire—exerts on ecosystem structure and function identifies it as a key management tool to conserve species and regulate ecosystem development. This is true especially of forest management where silviculture and fire are intimately linked through the interaction of spatial and temporal controls on litter production and resulting fire behavior. Understanding the influence of structure and function is a necessity for enhancing our ability to adaptively manage dynamic ecosystem that are maintained by fire. Dr. Robert Mitchell dedicated his life to contributing toward a better understanding and appreciation of the structure and function of ecosystems maintained by fire. The objective of this oral session is to bring together a series of researchers that focus their studies on understanding the structure and function of fire-maintained ecosystems with an emphasis on ecosystem carbon dynamics, resource allocation patterns, restoration leading to enhanced biodiversity, and ecological management practices. Included in this session are a small but representative sample of the numerous students and colleagues fortunate enough to have worked with Bob in his life-long commitment to science, management, policy, and mentoring. Understanding the complex linkages between these fields of ecological study becomes even more important with growing anthropogenic pressures across the globe that may hinder fire management activities and ultimately change the ecosystems that are maintained by fire.