Working Groups:

Pyrogeography - fire's place in earth system science
David Bowman and Jennifer Balch

It is time to rethink the place of fire on Earth. Megafires are currently overwhelming human control, despite huge budgets and mature fire-fighting technologies. There is mounting evidence that, beyond immediate destruction of life and property, landscape fires have long-term effects on global carbon stocks, biodiversity, climate, world economies, and human health. Despite fire's pervasive influence in many disciplines, there is no uniting theory or paradigm concerning the role of biomass burning in Earth science. Moreover, fire has not been satisfactorily considered by global change policy and ecosystem management. We, therefore, propose a thought experiment addressing (i) whether fire would evolve where carbon-based life is present, (ii) how it would evolve, and (iii) how humans, their cultures, and fire may have coevolved. We will combine knowledge about biomass burning across fields to develop an integrative paradigm of 'pyrogeography' that addresses these fundamental questions. This synthetic exercise will inform and coordinate participant's research to derive global products that highlight how and where shifting fire regimes will have consequences for human health, property, and ecosystem services - including global terrestrial carbon stocks. Our outputs will be a succinct review paper, an edited volume, and a concise book that collectively will: (i) provide a conceptual framework to account for the variation of fire types (intensity, frequency, and extent) in space, time, and amongst cultures, (ii) set out working hypotheses that will guide future work, and (iii) identify major omissions of fire's important role in Earth science and management. These outputs are a prerequisite for adaptation to the apparent recent intensification of fireclimate-vegetation feedbacks, which have been exacerbated by climate change, rapid land cover transformation, and exotic species introductions that challenge the evolutionary integrity of entire biomes. 

The role of niche conservatism in producing biodiversity gradients
Howard Cornell, Susan Harrison and Christy McCain

Species diversity at broad spatial scales increases most strongly with productivity (terrestrial realm) and temperature (marine realm). The reason for such global-scale trends is still unknown. Ecological mechanisms operate locally and therefore appear inadequate to explain why these patterns are strongest at the largest geographic scales. Our goal is to test a novel evolutionary/historical hypothesis - the climatic "niche-conservatism" hypothesis - which postulates that more species inhabit more productive or warmer environments because most higher taxa originated in such environments, and evolutionary constraints limit occupancy of colder or more arid regions. This hypothesis yields the testable prediction that ancestral climate state accounts for the strength of productivity- or temperature-richness relationships among taxa. We will test this using newly developed phylogenetic methods on both terrestrial and marine data. We will also quantify the timescales over which niche conservatism operates, analyze historical climate-richness data, and investigate possible mechanisms for niche conservatism.

Integrated history and future of people on Earth (IHOPE): Building a community data base and testing the resilience - sustainability hypothesis across scales
Robert Costanza, Lisa Graumlich, and Sander van der Leeuw

Understanding the reasons for the emergence, sustainability, decline, or collapse of human societies is a key prerequisite for creating a sustainable and desirable future. A central hypothesis is that the probability of societal collapse, or failure, increases with loss of resilience in social-ecological systems. The proposed working group will assemble integrated environmental and human historical data at the global scale for comparative analysis and for a few key case study areas for dynamic analysis in order to help build this understanding. We will develop criteria for integrating and analyzing disparate data across scales and disciplines. Key lessons from an ongoing project titled "Integrated Research Information System (IRIS)" using the ARCHAEOMEDES dataset from southern Europe (van der Leeuw, 1998, 2005) will be incorporated. A key component of this activity will be developing better ways to integrate and visualize data from the broad range of relevant sources (i.e. from historical narratives to ice cores) and with a broad range of spatial and temporal resolution and quality. In assembling the integrated data base the working group will also develop meta-variables and indices that can serve as proxies for environmental predictability and system resilience. We can then test the ability of various proxies of system resilience to explain sustainability or breakdown of social structures, relative to alternative hypotheses. A range of modeling approaches will be applied to the problem.

Developing an integrated botanical information network to investigate the ecological impacts of global climate change on plant biodiversity
Brian Enquist, Richard Condit, Robert Peet, Brad Boyle and Steven Dolins

Many of the major questions in ecology span enormous geographic and temporal scales, yet much ecological knowledge is still based on observations of individual investigators conducted at single locales, often covering scales of only a few hundred square meters. Understanding ecological patterns and predicting future changes, including those caused by human impact, necessitates a holistic approach covering large spatial scales, and this will only be achieved by identifying, retrieving, and synthesizing diverse data from distributed sources: heterogeneous data from a global confederation of collaborating scientists including a broad range of disciplines. To address this pressing need, we propose to network eight of the largest databases on plant inventories in the Americas to assemble an accessible and readily analyzable database warehouse on distributions and abundances. With it, we will answer major questions of direct relevance to conservation of new world biota. In particular, how does climate and latitude influence the relative distribution and abundance of narrow and widespread plant species? While this and associated questions have been mainstays for ecology our inability to integrate data has significantly limited our ability to answer them. The proposed working group will significantly improve our ability to finally answer these questions. We will also make distribution and abundance data widely available so that further analyses, for example covering other plant taxa or particular regions, will be possible. It is also part of our plan to continue expanding our meta-database with additional inventories, collections, and plots not yet digitized, plus future field work. This data network will provide a baseline of critical data that will allow ecologists to address fundamental issues in plant ecology and global change biology.

Benchmarking ecosystem response models with experimental data from long-term CO2
Richard Norby, Yiqi Luo, Ram Oren, I.C. Prentice, and Paul Hanson

Ecosystem models have been increasingly incorporated into earth system models to predict climatic and atmospheric dynamics. However, ecosystem models themselves are far from perfect and need continued improvement. We will advance this necessary model improvement using some of the longest and most comprehensive data sets on CO2 impacts on ecosystems from field experiments. Twelve ecosystem process and land surface models, which are being used for predicting terrestrial response to atmospheric and climatic change, will be parameterized with site and weather data from the Duke University and Oak Ridge National Laboratory free-air CO2 enrichment (FACE) experiments. We will evaluate the ability of the models to reproduce the measured processes of the carbon, water, and nitrogen cycles of the experimental forest stands and their responses to elevated atmospheric CO2 concentration. Similarities and differences among the models and their components will provide guidance for improving all of the models. With the experimental data as a benchmark for model performance, the utility of the models for extrapolation to environmental change questions can be demonstrated with increased confidence. This working group will include participants who are most familiar with the experimental data, a data manager to assemble and format the data for model input, representatives from diverse modeling groups, and a neutral observer to synthesize model results. This data-model intercomparison project has the potential to provide better scientific outputs for policy making. 

Postdoctoral Associates:

Duncan Menge
Synthesizing ecosystem development data in a theoretical framework to understand transitions from nitrogen limitation to colimitation to phosphorus limitation 

The ability of ecosystems to sequester carbon (C) and help mitigate climate change depends on which factors limit C uptake into vegetation. It is increasingly clear that nitrogen (N) and phosphorus (P) play critical roles in regulating C uptake, and forests tend to transition from N limitation to colimitation to P limitation as they develop from bare ground. However, at present there is no theoretical framework that determines the conditions under which each resource limits production, or when transitions between the different states should occur. At NCEAS I will build such a theoretical framework, synthesize existing data from forest chronosequences worldwide, and combine theory with data to analyze transitions between the alternate ecosystem states of limitation by N, P, or both. 

Sadie Ryan
Quantifying long-term landscape vegetation dynamics in and around Kibale National Park, Uganda, to establish appropriate landscapes for zoonotic disease models 

Models of zoonotic diseases, particularly those at the spillover interface, require a certain degree of spatial information that theoretical, spatially implicit models cannot always encompass. This is often the situation for parasitic or locally contaminant infectious diseases, or location-specific reservoirs that re-infect populations. For these types of diseases, particularly those that may be the subject of vaccination programs, agent-based models incorporating explicit landscapes may provide a more appropriate framework for analyzing disease spread. However, introducing the complexity of geographically explicit landscape interactions, particularly with temporal dynamics, is irrelevant if the mechanisms and agency of disease spread within that landscape is not reducible to patterns at a scale meaningful to the model's mechanistic drivers. In this project I propose to examine a specific landscape, Kibale National Park, Uganda, in which primate parasitic disease, anthropogenic fragmentation and climate change are posited to be interacting. I am currently working on agent-based models of zoonotic diseases, particularly addressing the human-primate interface, and would like to complement this work with quantified, data-driven dynamic landscapes. This will lay the groundwork for similar approaches in other sites and scenarios, such as Ebola vaccination in gorillas (with P. Walsh, NCEAS working group) and control of SIV or respiratory disease transmission in Gombe chimpanzees (with M. Wilson and A. Pusey, Jane Goodall Institute, MN). 

Nathan Swenson
On the relationship between species, phylogenetic and functional diversity in plant communities on a continental scale

Naturalists have long marveled at the spectacular degree of botanical diversity in our world. Geographic gradients in plant species diversity (SD) have been documented on large- and small-scales, but we have little to no knowledge regarding large-scale gradients of plant phylogenetic and functional diversity. It is critical that this knowledge gap be filled as the phylogenetic diversity (PD) and functional diversity (FD) of communities is of interest to those setting conservation priorities and predicting ecosystem resilience to global change respectively. Further, gradients in PD and FD both hold the potential to provide novel and mechanistic insights into the factors promoting gradients in plant SD. The proposed research will combine several plant functional trait databases, large databases of woody plant inventory plot data generated from a concurrently proposed NCEAS Working Group and phylogenetic supertrees in order to: (i) provide the first maps of plant FD on a continental scale; and (ii) test whether gradients in PD and FD are correlated with gradients in SD and under what circumstances they deviate. If biotic interactions and evolutionary history increase SD, then it is expected that plot-level PD and FD will be higher than that expected given the SD in the plot. It is expected that the proposed work will not only provide critical insights into these three components of plant biodiversity, but it will also provide the first continental scale maps of plant form and function that may be used in numerous future investigations into problems ranging from modeling plant community assembly to predicting ecosystem response to global change.

Sabbatical Fellows:

William Fagan
Dendritic landscapes: Exploring connectivity and biodiversity in an alternative geometry

As an NCEAS Sabbatical Fellow, I will explore the implications of dendritic (branching) geometries, such as those found in river networks and elsewhere in nature, for ecological complexity through the development of theoretical models. 

Kerry Woods
Slow systems and complex data-sets: Multi-decade permanent plots permit address of recalcitrant questions about late-successional forests

Long-standing (and often conflicting) hypotheses about processes in late-successional forest communities remain effectively untested because existing data-sets are inadequate for analysis of very slow processes. Usual approaches are of limited power because they employ assumption-laden indirect methods or data-sets of low precision and resolution. Large, multi-decade, spatially explicit data from systems of permanent plots in old-growth forests in Michigan afford the potential for rigorous address of a range of important but recalcitrant questions. Are community and population processes stabilizing and convergent, or non-equilibrial and historically contingent? Is diversity maintained by equilibrial or non-equilibrial processes? How do frequency and scale of different types of disturbance interact with population dynamics and  interactions? Are tree growth and biomass accumulation related to diversity? How do spatial and temporal scale and resolution affect answers to these questions? The data-set, while uniquely appropriate for assessing these questions, is also very complex - irregular in structure and complexly stratified in time and space - posing daunting methodological challenges. This project has two general goals that will make use of the distinctive resources and mission of NCEAS. First, I hope to collaborate with NCEAS staff and guests in developing and applying models and analytic approaches appropriate to these research questions and commensurate with the properties of the data set (I particularly hope to establish ongoing collaborations). Second, I hope to make this data-set available to the larger community of researchers by archiving it in the NCEAS data repository and developing structures for continual updating as new layers of data are acquired.