Research in the Fridley Lab at Clemson University concerns the ecology of plant communities, including their organization, their distribution, and their control over ecosystem processes. Much of our work is performed in the context of species invasions and environmental change, using approaches that span from genomics and physiology to climatology, landscape ecology, and biogeography.
Plant invasions in a global floristic context
The introduction and spread of plant species to areas distant from their native ranges is a complex biological process that gets to the heart of how plant communities are assembled. It is also a phenomenon of great public importance, given the economic and environmental ramifications of wholesale changes to ecosystems caused by invasive plants. We seek to understand properties of ecosystems that make them susceptible to invasion and properties of species that make them invasive.
A focus of this project is a large group of shade-tolerant, fast-growing woody species spreading throughout forests of the Americas. Our aim is to understand basic differences in the biology of these groups using a combination of laboratory, common garden, and field approaches with international collaborators.
Topographic drivers of montane vegetation dynamics
Great Smoky Mountains National Park in the Southern Appalachians has been a hotbed of ecological research for over half a century, in part due to its extreme topographic gradients that underlie what R.H. Whittaker called the most complex vegetation in North America. We are using decades of plant distribution data with our distributed ground-level meteorological network to address how topography interacts with regional climate to drive plant community dynamics. This involves monitoring of the vegetation (e.g., tree ring analyses) and environment (temperature, soil moisture, nutrient probes) across fine-scale spatial gradients. A new collaboration has expanded this work to Rocky Mountain National Park (CO).
Vegetation response to climate change
North-temperate ecosystems are expected to warm considerably over the coming century, which may force large shifts in the composition and functioning of terrestrial vegetation. For many years we have worked with UK colleagues on one of the longest running manipulations of temperature and precipitation on a steep daleside in northern England. Established in 1992, the Buxton Climate Change Impacts Lab has demonstrated that some ecosystems may be relatively resistant to climate forcing. Recent studies focused on whether such resistance stems from 1) high fine-scale substrate heterogeneity, 2) dispersal limitation of potential invasive species, or 3) the capacity of existing populations to evolve quickly in response to new climate regimes.
Biodiversity dynamics: scale and function
We have long standing interests in the causes and consequences of plant diversity, using experimental and survey-based approaches. For example, past research using experimental microcosms has established links between the local genotypic diversity of limestone grassland species and rates of pasture productivity. Most of the plants of this community are obligate outbreeders that display considerable local variation, much of which has been shown to have a genetic basis. We have shown that such differences between individuals are an important driver of the overall biodiversity of this ecosystem.
We also have interests in the measurement and interpretation of survey-based plant diversity data. Patterns of biodiversity—such the number of species in a given area—are scale-dependent, meaning that their shape depends on the spatial grain and extent examined. As a consequence, many of the most well-studied patterns in ecology—such as species-area and species-time curves, species-abundance distributions, measures of beta diversity, diversity-environment relationships—all take on different functional forms when examined in small vs. large areas (or over small vs. long durations), and will thus defy generalization until researchers can account for scale sensitivity. We are particularly interested in how the distribution of plant diversity at ‘fine' scales (e.g., vegetation plots) reflects the distribution of diversity at broader scales.