Overview & General Approach
The goal of the research conducted in the group is to leverage information regarding intra- and inter-specific variation in organismal performance to understand and predict the past, present and future distribution of biodiversity. In pursuit of these research goals, our approach follows two guiding principles. First, we believe that the grand challenges facing scientists today require integrative approaches that draw from the concepts and techniques from many fields. We achieve this within the lab by attempting to tackle problems from genomes to forest canopies. Second, our research approach necessitates the collection and analysis of large datasets that document the distribution and dynamics of plant species on a global-scale. These data allow us to quantify the drivers of tree distributions and demography, which is an essential step for predicting the fate of individual species and forests in the future.
Current Major Research Foci
Researchers in the group work in temperate, subtropical and tropical forests worldwide. Currently, we conduct field work in the forests of the Eastern United States, Puerto Rico, Colombia, and southeast Asia. The research group is located in the Department of Biological Sciences the University of Notre Dame. The hub for our research on trees in eastern North America is the University of Notre Dame Environmental Research Center (UNDERC), which is also a National Science Foundation NEON site. Our current major research foci are the following:
1) Linking anatomical and physiological traits to individual tree performance and, ultimately, to population and community structure and dynamics – The structure and dynamics of forests are the emergent properties of individual-level demographic outcomes. These outcomes, themselves, are due to how individuals interact with their environment upon the basis of their functional strategies. As such, our group has a major focus on establishing the linkages between phenotypes and demographic outcomes given various abiotic and biotic contexts. Recently, a good portion of this work focuses on how the relationship between a trait and demographic rates is dependent upon the values of other traits that make up a phenotype, how spatial and temporal variation in the environment impact seedling and tree performance and whether less-commonly measured traits and whole plant biomass allocation can improve models of tree growth and mortality. We conduct this work worldwide including in Smithsonian ForestGeo plots and the University of Notre Dame Environmental Research Center (UNDERC).
2) The dimensions of biodiversity, life history tradeoffs and life stage transitions in eastern North American and east Asian trees – Projections of future forest composition, dynamics, functioning and services, therefore, rely on our ability to identify the drivers of individual tree performance. Theory elucidates how the environment and life history tradeoffs should impact individual tree performance across the life cycle. A robust empirical literature accompanies this theoretical literature, but it is limited in several important ways. First, it often considers a single life stage transition (e.g. survival from the seedling to juvenile stage) or a single tradeoff (e.g. allocation to reproduction versus growth), which reduces of our ability to model whole populations and ultimately forest dynamics. Second, it frequently does not consider multiple functional groups or forest types, which leads to uncertainty regarding the generality of the findings and the degree to which individual- or species-level information must be considered in projections of forest dynamics. Lastly, it often fails to consider how changes in the abiotic and biotic environment will alter tradeoffs and demographic outcomes, which reduces our ability to project the fate of forests in the Anthropocene. The core research questions we ask in this research project are the following: (1) Are the drivers of the tradeoffs underlying tree performance consistent across a taxonomically and functionally diverse sample of species?; (2) How does intra-specific functional and genetic similarity of individuals within a population linked to their demographic success?; (3) How does intra-specific functional and genetic diversity vary across populations and how is this linked to tree performance across life stages?; and (4) How does variation in the abiotic and biotic environment drive tree performance and can this be understood in the light of functional, phylogenetic and genetic information? This work is being conducted in ForestGeo plots and UNDERC and is funded by the National Science Foundation (NSF) Dimensions of Biodiversity program.
3) Tree gene expression in response to temporal variation in the environment - Forested ecosystems are key players in the global carbon cycle. A grand challenge for those investigating current and projecting future forest functioning is linking processes occurring at the level of a leaf to those occurring at the level of a forest. Critical to these efforts is an understanding of where variation exists and the degree to which knowing that information improves projections. Individuals interact with their environments via their phenotypes and the resulting performance ultimately scales up to provide emergent ecosystem-level properties. Thus, acute and chronic changes to the environment are inherently an individual-level phenomenon. Rich assays of leaf level functioning and linkages of such information to individual tree and whole forest carbon flux are rare in tree ecology due to logistical constraints and a focus on a handful of leaf properties. This project focuses on assaying leaf gene expression throughout the growing season over several years in two NSF NEON research sites with ForestGeo plots – Harvard Forest and the Smithsonian Environmental Research Center. The initial work was funded by the NSF Macrosystems Biology – Early NEON Science program and it was recently extended to quantify how leaf gene expression changed due to reduced atmospheric pollutants resulting from the Covid-19-induced shutdown of work in the DC metro area (i.e. during the “Anthropause”). Previous work in the lab on gene expression has focused on how trees native to Wisconsin differentially express their genes in response to drought. That work demonstrated that gene expression responses to experimental drought are superior predictors of natural tree distributions in a forest plot than the anatomical and physiological traits commonly measured by ecologists.
The goal of the research conducted in the group is to leverage information regarding intra- and inter-specific variation in organismal performance to understand and predict the past, present and future distribution of biodiversity. In pursuit of these research goals, our approach follows two guiding principles. First, we believe that the grand challenges facing scientists today require integrative approaches that draw from the concepts and techniques from many fields. We achieve this within the lab by attempting to tackle problems from genomes to forest canopies. Second, our research approach necessitates the collection and analysis of large datasets that document the distribution and dynamics of plant species on a global-scale. These data allow us to quantify the drivers of tree distributions and demography, which is an essential step for predicting the fate of individual species and forests in the future.
Current Major Research Foci
Researchers in the group work in temperate, subtropical and tropical forests worldwide. Currently, we conduct field work in the forests of the Eastern United States, Puerto Rico, Colombia, and southeast Asia. The research group is located in the Department of Biological Sciences the University of Notre Dame. The hub for our research on trees in eastern North America is the University of Notre Dame Environmental Research Center (UNDERC), which is also a National Science Foundation NEON site. Our current major research foci are the following:
1) Linking anatomical and physiological traits to individual tree performance and, ultimately, to population and community structure and dynamics – The structure and dynamics of forests are the emergent properties of individual-level demographic outcomes. These outcomes, themselves, are due to how individuals interact with their environment upon the basis of their functional strategies. As such, our group has a major focus on establishing the linkages between phenotypes and demographic outcomes given various abiotic and biotic contexts. Recently, a good portion of this work focuses on how the relationship between a trait and demographic rates is dependent upon the values of other traits that make up a phenotype, how spatial and temporal variation in the environment impact seedling and tree performance and whether less-commonly measured traits and whole plant biomass allocation can improve models of tree growth and mortality. We conduct this work worldwide including in Smithsonian ForestGeo plots and the University of Notre Dame Environmental Research Center (UNDERC).
2) The dimensions of biodiversity, life history tradeoffs and life stage transitions in eastern North American and east Asian trees – Projections of future forest composition, dynamics, functioning and services, therefore, rely on our ability to identify the drivers of individual tree performance. Theory elucidates how the environment and life history tradeoffs should impact individual tree performance across the life cycle. A robust empirical literature accompanies this theoretical literature, but it is limited in several important ways. First, it often considers a single life stage transition (e.g. survival from the seedling to juvenile stage) or a single tradeoff (e.g. allocation to reproduction versus growth), which reduces of our ability to model whole populations and ultimately forest dynamics. Second, it frequently does not consider multiple functional groups or forest types, which leads to uncertainty regarding the generality of the findings and the degree to which individual- or species-level information must be considered in projections of forest dynamics. Lastly, it often fails to consider how changes in the abiotic and biotic environment will alter tradeoffs and demographic outcomes, which reduces our ability to project the fate of forests in the Anthropocene. The core research questions we ask in this research project are the following: (1) Are the drivers of the tradeoffs underlying tree performance consistent across a taxonomically and functionally diverse sample of species?; (2) How does intra-specific functional and genetic similarity of individuals within a population linked to their demographic success?; (3) How does intra-specific functional and genetic diversity vary across populations and how is this linked to tree performance across life stages?; and (4) How does variation in the abiotic and biotic environment drive tree performance and can this be understood in the light of functional, phylogenetic and genetic information? This work is being conducted in ForestGeo plots and UNDERC and is funded by the National Science Foundation (NSF) Dimensions of Biodiversity program.
3) Tree gene expression in response to temporal variation in the environment - Forested ecosystems are key players in the global carbon cycle. A grand challenge for those investigating current and projecting future forest functioning is linking processes occurring at the level of a leaf to those occurring at the level of a forest. Critical to these efforts is an understanding of where variation exists and the degree to which knowing that information improves projections. Individuals interact with their environments via their phenotypes and the resulting performance ultimately scales up to provide emergent ecosystem-level properties. Thus, acute and chronic changes to the environment are inherently an individual-level phenomenon. Rich assays of leaf level functioning and linkages of such information to individual tree and whole forest carbon flux are rare in tree ecology due to logistical constraints and a focus on a handful of leaf properties. This project focuses on assaying leaf gene expression throughout the growing season over several years in two NSF NEON research sites with ForestGeo plots – Harvard Forest and the Smithsonian Environmental Research Center. The initial work was funded by the NSF Macrosystems Biology – Early NEON Science program and it was recently extended to quantify how leaf gene expression changed due to reduced atmospheric pollutants resulting from the Covid-19-induced shutdown of work in the DC metro area (i.e. during the “Anthropause”). Previous work in the lab on gene expression has focused on how trees native to Wisconsin differentially express their genes in response to drought. That work demonstrated that gene expression responses to experimental drought are superior predictors of natural tree distributions in a forest plot than the anatomical and physiological traits commonly measured by ecologists.