Past projects
Biodiversity-Stability
Do more diverse ecosystems behave more consistently? I helped several researchers at the Department of Organismic and Evolutionary Biology, Harvard University, to answer this question in a greenhouse experiment. We found that diversity and planting density interactively influenced biomass production (our "ecosystem function"), such that high density compensated for a lack of diversity (He,Wolfe-Bellin, Schmid, and Bazzaz 2005). Following up on this research, I analyzed the the stability of biomass production at each level of organization: population-, functional group-, and community-wide stability. We found that stability of biomass production was high at the whole-community level, and this emerged from a combination of statistical averaging and compensation between plant groups (Flynn, Schmid, He, Wolfe-Bellin, and Bazzaz 2008).
Succession and large-scale distubance
How do successional processes interact with landscale-scale disturbances to shape biological communities? I worked with Maria Uriarte and another student at E3B, Tanja Crk, to investigate this question in the secondary forests of Puerto Rico. In these stands, we have good information about both the land use history and history of exposure to hurricane winds. We have found that the interaction of land use history and hurricane winds can influence stand structure and species composition in modest ways (Flynn et al, in press, Biotropica).
Insect-plant interactions under global change
How sensitive will insects be to changes in plant chemistry as the world heats up? Will plants be more or less susceptible to the negative effects of herbivory as CO2 accumulates in the atmosphere? To determine how rising CO2 and air temperature might affect insects and plants, I grew bittersweet nightshade (Solanum dulcamara) under two CO2 and three temperature conditions, in the presence or absence of the aphid Myzus persicae. I found that the effect of temperature on this system was far more consistent than that of CO2, with the maximum photosynthetic capacity of the plants rising and aphid populations growing with increases in ambient temperature. This indicates that the advantages to insects in a warmer world may outweigh those of plants (Flynn, Sudderth, and Bazzaz, 2006).
Global change and plant reproductive biology
What rules guide parental provisioning of offspring? One proposal has been that the relative size of resource pools available to parents determines how large their offspring will be. For plants, this would mean that the ratio of key nutrients available to the parental plants might determine seed size. We tested this idea by growing pokeweed (Phytolacca americana) under two CO2, two N-supply, and three planting density treatments. Higher foliar C:N ratios consistently correlated with larger seeds. This supported the resource-ratio offspring hypothesis. However, under elevated CO2, plants allocated fewer resources to seed production, so average mass of individual seeds was less (He, Flynn, Wolfe-Bellin, Fang, and Bazzaz 2005).