past research

Phenology of Wild Species | Detritus 

The Temporal Ecology Lab focuses on the question: How does global change alter the temporal assembly and disassembly of communities? In particular we study how humans have fundamentally altered how organisms experience time through changes to habitat structure, disturbance cycles, and the global climate system. Our long-term goal is to better understand the mechanisms that drive global change impacts on species, communities and ecosystems so that we can reliably forecast ecological responses and aid in mitigating unwanted consequences. We are especially lucky that this goal lets us tackle a lot of interesting fundamental science.

In addition to the below work, the lab also works on winegrapes.

Phenology of wild plant species

Forecasting phenology: Integrating ecology, climatology, and phylogeny to understand plant responses to climate change


Understanding species responses to climate change has been a major focus of ecology in recent years. A suite of responses has been documented related to timings of life history events (phenology), with some species altering their phenology earlier or later, while other species change little. Robust explanations for this diversity of phenological responses are largely absent from the literature, but are crucial for predicting how communities and the ecosystem services they provide will change in the future. To fill this gap, we synthesized observational and experimental phenology studies across North America and Europe. Because understanding phenology is inherently an interdisciplinary problem, our working group brought together ecologists, climatologists, and phylogeneticists to address phenological responses to climate change at the species and community levels. We organized our efforts into two parts. First (1), we conducted a meta-analysis that compared short-term (most <5 years) experimental studies to longer-term (generally >20 years) observational studies. This tested how responses to shorter-term climate forcing scale up to longer term responses. Second (2), we used some of the longest plant phenology datasets from North America and Europe, spanning over 150 years, to test how well the evolutionary history of plant traits can predict species responses to climate change.

You can read more about the project here, which includes a photo of a quorum of the group and a list of all related data products and publications.

Predicting future springs: Reconciling experimental and observational approaches for climate change impacts


Following up on earlier work, which found results obtained from observational versus experimental studies make different predictions for future plant phenology, Ailene Ettinger and I are leading a new exploratory working group on the issue. Our goal is to bring together scientists from around the world, who have experience with phenological studies and will provide diverse datasets, knowledge, and ideas to examine possible underlying causes of this discrepancy through analyses of more fine-scaled climate and phenological data.

Detritus in food webs

Field experiment: Grass invasion in coastal scrub – San Diego, California

Invasion by exotic plant species threatens biodiversity and ecosystem functioning worldwide. My PhD research combined field experiments with mathematical modeling to characterize complex interactions among abiotic and biotic factors in plant communities, thereby elucidating both impacts and mechanisms of plant invasions. Grass invasion increased both productivity and soil moisture, which enabled native and exotic plant species to co-exist, and indirectly supported larger and richer arthropod communities. Experimentally added exotic grass litter also increased soil carbon and nitrogen pools by 20% in only two years, showing that ecosystem responses to invasion can be more dynamic than previously believed. Together my findings demonstrated that field experimentation can reveal community and ecosystem impacts of invasion that differ substantially from observational studies.

Papers in EcologyGlobal Change BiologyJournal of Vegetation Science, and Oecologia give detail on my findings.

Models & Synthesis: Brown-green omnivory across food webs

Understanding the prevalence and role of omnivory in food webs is a long-standing area of research in community ecology. Recent work suggests that multi-channel omnivory—feeding on distinctly different food sources—may structure food webs and promote trophic cascades. Collaborating with Claire de Mazancourt, Stefano Allesina and Kathy Cottingham, John Moore, Stuart Sandin, we used empirical data and modeling to test the prevalence and effect of a common type of multi-channel omnivory, feeding on both living-autotroph (green) and detritus-based (brown) webs. Considering 23 food webs spanning terrestrial, freshwater and marine systems, we found that brown-green omnivory is common across all ecosystem types, occurring most often among primary consumers. Therefore, we developed a simple four-compartment nutrient cycling model for consumers eating autotrophs and detritus. Our model results show that across terrestrial and aquatic systems, omnivorous consumption of detritus is destabilizing at high attack rates on the autotroph, and stabilizing at low attack rates on the autotroph; however, the set of conditions for stable webs with omnivory is much narrower for aquatic systems. Together our results demonstrate that brown-green omnivory is extremely common across ecosystems and may be a stabilizing force in real webs.

After many years our findings finally came out in late 2014 in Ecology.