Environmental change and succession in arid ecosystems

I am thrilled to have recently started on a project with Jonathan Bakker (UW) and Matt Davies (OSU) examining compositional trajectories of sagebrush-steppe communities in central Washington state. Sagebrush-steppe is an imperiled arid ecosystem in the Intermountain West threatened by cheatgrass invasion, increased wildfire frequency, overgrazing, climate change, and widespread clearing. Our project combines new and historical data to disentangle the responses of this ecosystem to natural and anthropogenic changes over immediate and long timescales. We are also quantifying the recovery of these communities to various restoration treatments applied at multiple spatial and temporal scales. This project is a multi-agency collaboration between UW, OSU, US Fish & Wildlife Service, Joint Fire Science Program, and the Department of Defense.

Multispecies coexistence in annual plant systems

My postdoctoral research with Margie Mayfield (UQ) and Janneke HilleRisLambers (UW) focused on quantifying the relative influences of biotic interactions and environmental variation on native and exotic species’ success. Using the diverse annual plant communities of Western Australia’s York gum woodlands as a study system, I employed experimental and statistical modelling approaches to examine variation in  coexistence predictions along competitive and environmental gradients. A manuscript detailing our findings are currently in review.

I am also involved in a project led by Margie Mayfield and Daniel Stouffer (University of Canterbury) examining the role of intransitive population dynamics in promoting coexistence in annual plant communities. A manuscript on this topic is currently in press at Journal of Ecology.

Global change and ecosystem functioning

My PhD research with Margie Mayfield, Richard Hobbs (UWA), John Dwyer (UQ), and Robert Holt (UF) examined species interactions and diversity-function relationships in “novel” and original plant communities. I showed that diversity within the exotic constituent of novel communities is currently under-appreciated, particularly in terms of actual competitive impacts exerted on native species over local scales. While competitive exclusion of native species is an outcome of these interactions (including through litter deposition), neutral and facilitative interactions are just as prevalent (manuscript in preparation), suggesting that many aspects of original community function can be retained or even enhanced. Headed by John Dwyer, we also showed that compositional and functional trait responses to eutrophication are contingent on climate.

While some ecological processes may be resilient to invasion, others may be more sensitive, such as the delivery of pollination services. This research, led by Xingwen Loy (Emory), highlights the importance of considering multiple trophic levels when assessing invasion impacts on native community functioning.

Ecology theory and restoration

My Master’s research with Elsa Cleland  (UCSD) combined ecological theory and application by using assembly rules to help restore a coastal sage scrub community dominated by invasive annual grasses. By harnessing prior knowledge of invader germination strategies, we turned the seasonal priority effect exerted by invasives on co-occurring natives into a “priority disadvantage”.

While scores of ecologists have heralded the potential utility of theory in restoration settings, the integration of these fields is still relatively uneven. As such, I recently led a review of the ecological restoration literature to pinpoint when and how community ecology theory has been used in restoration settings.

I am also involved in a project led by Timothy Staples (UQ) investigating large-scale trends in information flow across several sub-fields of applied ecology (in review).