I am generally interested in community ecology and conservation biology. Most of my previous and current research has focused on coastal ecosystems. Coastal ecosystems, often with striking community patterns and steep environmental gradients, are ideal models for community ecology studies. They are also some of the most invaluable ecosystems on Earth due to the ecosystem and societal services they provide, but have been increasingly impacted by humans for millennia for resource extraction, transportation, waste disposal and shoreline transformation. My research interests extend to other ecosystems of Earth.
In the future, I hope to focus on conservation research that is more likely to be meaningful to the society. Where appropriate, I would also like, and make efforts, to make the research macroscopic, multidisciplinary, and built on solid experiments and statistics.
PREVIOUS RESEARCH SUMMARIES
Bottom-up, inter-specific and top-down determinants of coastal plant communities in the Yellow River and Yangtze estuaries, China
This is my earliest research, mainly experimental studies, begun since I was a second-year undergraduate student. I conducted a series of field surveys, field manipulative experiments, common garden experiments and lab analysis to examine various types of determinants of coastal plant communities in the Yellow River and Yangtze estuaries and their relative importance across spatial and temporal scales. My results show that (i) both bottom-up factors (salinity, flooding, warming, alteration in precipitation, etc.) and inter-specific interactions contribute to the patterns of the plant communities in the estuaries, whereas their relative importance varies with spatial (e.g. spatial scale and topographical gradients) and temporal factors (e.g. plant life history stage); (ii) the importance of facilitative interactions among plants increases with increasing stress within the tolerance range or the fundamental niche of a given species, and can be fundamentally determined by plant traits like stress tolerance and competitive ability; (iii) Spartina alterniflora invasions can significantly alter crab communities in the Yellow River estuary by increasing density and biomass of some specific species and decreasing the total diversity, and Spartina invasions will likely be constrained to low-elevation mudflats and marshes by hypersaline stress rather than inter-specific competition at upper elevations; and (vi) top-down factors such as crab herbivory are also important in mediating dynamics of the marsh dominant plant Suaeda salsa, while their importance varies as a function of flooding and vegetation abundance. Many of these results have already been published in scholarly journals like Ecology, Oecologia, PLoS ONE (see Publications), while others are in preparation or remain underway.
Global shifts towards positive species interactions with increasing environmental stress
This is my first synthetic research, done during my visiting study at Brown in 2011. I conducted a global synthesis of plant interactions along stress gradients. Despite increasing recognition of the role played by positive species interactions, there is still not general agreement on whether positive and negative species interactions predictably shift with changing environmental conditions as hypothesized by the Stress Gradient Hypothesis (SGH). Based on extensive literature searches and author data requests, I built a comprehensive dataset of > 700 tests of the SGH in plant communities from six continents. Using this global dataset and various statistical validations, I rigorously examined the generality of the SGH across various stresses, plant traits, ecosystems, climates, and methodologies. My results show that interactions among plants are increasingly positive as environmental stresses increase. This finding is general across stress type, evident with algae, grasses, shrubs, trees, natives and exotics, and holds in ecosystems as varied as forests, grasslands, wetlands, and oceans. My analysis further identifies how the magnitude and nature of the shifts toward facilitation with stress can vary depending on ecological factors of general interest. I make suggestions of how future research should move forward by examining how facilitation in communities can be better predicted by incorporating those factors in addition to stress, by identifying areas that are relatively understudied, and by suggesting that the SGH has unrealized potential for conservation applications. This research was published in Ecology Letters.
He, Q., Bertness, M.D.*, Altieri, A.H. 2013. Global shifts towards positive species interactions with increasing environmental stress. Ecology Letters 16: 695-706.
Press release: http://news.brown.edu/pressreleases/2013/01/ecostress.
Media coverage: Science Daily, EurekAlert!, Phys.org, redOrbit, and many others.
He, Q., Cui, B., Bertness, M.D., An, Y*. 2012. Testing the importance of plant strategies on facilitation using congeners in a coastal community. Ecology 93: 2023–2029.
He, Q., Cui, B.S.*, An, Y. 2012. Physical stress, not biotic interactions, preclude an invasive grass from establishing in forb-dominated salt marshes. PLoS ONE 7: e33164.
He, Q., Chen, F.Y., Cui, B.S., An, Y*. 2012. Multi-scale segregations and edaphic determinants of marsh plant communities in a western Pacific estuary. Hydrobiologia 696: 171–183.
He, Q., Cui, B.S., An, Y*. 2011. The importance of facilitation in the zonation of shrubs along a coastal salinity gradient. Journal of Vegetation Science 22: 828–836.
Cui, B.S.*, He, Q., An, Y. 2011. Spartina alterniflora invasions and effects on crab communities in a western Pacific estuary. Ecological Engineering 37: 1920–1924.
Cui, B.S.*, He, Q., Zhang, K.J., Chen, X. 2011. Determinants of annual-perennial plant zonation across a salt-fresh marsh interface: a multistage assessment. Oecologia 166: 1067–1075.
Cui, B.S.*, He, Q., An, Y. 2011. Community structure and abiotic determinants of salt marsh plant zonation vary across topographic gradients. Estuaries and Coasts 34: 459–469.
He, Q., Cui, B.S.*, Cai,Y.Z., Deng, J.F., Sun, T., Yang, Z.F. 2009. What confines an annual plant to two separate zones along coastal topographic gradients? Hydrobiologia 630: 327–340.
Please see my CV in pdf.