R codes / models
My lab is currently working on a set of multivariate experiments aimed at better understanding the multiple controls on community assembly and ecosystem processes.
I am particularly interested in several areas of community ecology:
1. Ecological Assembly Rules -- trait- and phylogenetically-based approaches for investigating the constraints on which subsets of species from regional and local species pools form communities. A key aspect of this is the investigation of trait and phylogenetic dispersion within communities, and the relationships between plant functional traits and performance on real geographies and in real time, and the use of structural modeling (a generalized form of path analysis) to assess the relative and independent effects on history, resources, and interactions on the assembly process.
2. Biodiversity. I am particularly interested in investigating how multiple factors (resources, stress, disturbance, etc.) affect local species density (alpha diversity), beta diversity (a measure of heterogeneity), and larger-scale diversity of species pools.
3. Ecosystem Processes. We are also working on the related issues of how the properties of communities (e.g., diversity, functional trait composition) affect processes such as primary production, nitrogen mineralization, and soil carbon storage. There has been great interest recently in whether diversity promotes ecosystem processes. Our goal is to use structural modeling to assess the relative roles of diversity, functional composition, and abiotic factors on these key processes.
4. Interactions. Ecologists have long been interested in investigating the strength of competition among species and along resource gradients. I am interested in the "interactions" of competition, mutualism, and herbivory, or perhaps more simply, the contingencies and complexities among plant-plant, plant-fungal, and plant-herbivore interactions. I am also interested in assessing the relative roles of community composition, diversity, and resources on these contingent interactions.
5. Restoration. I like to think that a lot of this work has implications for restoration and management. Therefore, my students and I are also working on some rather applied questions, such as what factors contribute to C4 grass establishment? Are native and non-native species equivalents, or have they evolved different combinations of trait values? Is the diversity of native and non-native species under similar controls?
6. Collaboration. I am also interested in collaborating in order to expand the breadth of components in these studies. For example, some student projects involve, for example: the responses of functional traits and leaf gas exchange to fungal suppression, assessing herbivore communities, soil eubacterial diversity, ground-layer invertebrates, and habitat use by small mammals. These collaborative projects are also noted below.
Core field crew, 2006
front row: Katelin Holm, Artur Stefanski
back row: Kristin Haider, Tina Dahlheimer, Mike Fell
Artur Stefanski collecting biomass, August 2006
Helianthus grosseserratus amid other native forbs, 2006
Biomass harvest, August 2006
Deb Freund and friends broadcasting seeds, November 2003
Freund site after site prep, November 2003
Shoreline restoration at Lake Wissota
Evan Weiher at Bon Secour National Wildlife Refuge