Research Interests

We study the population ecology plants with a focus on rare and invasive species, and address questions related to the causes and consequences of their abundances and distributions. Why are some species rare, while their closely related congeners are widespread? How does dispersal ability and density dependence determine the population abundance and spread of invasive plants? In particular, we focus on the role of interspecific interactions between plants and pollinators, herbivores, seed predators and competitors on the long term rates of plant population growth. We also study how these interactions, particularly plant-pollinator networks, have changed through time as a result of changes in our landscape use and climate. Our study sites include the Tyson Research Center near St. Louis, Missouri and surrounding natural areas in Missouri and Illinois, Point Reyes National Seashore in Northern California, several military bases on the Hawaiian Islands (Oahu and Hawaii), and villages near Bangalore, India.

Caption: Removal of invasive vetch from our experimental prairie designed to compare the differences in performance of invasive Lespedeza cuneata with native Lespedeza capitata in different nutrient and plant community composition environments.

Selected Publications

Knight, T.M. 2012.  Using Population Viability Analysis to Plan Reintroductions.  In J. Maschinski and K.E. Haskins (Eds.), Plant Reintroduction in a Changing Climate The Science and Practice of Ecological Restoration (pp. 155-169). Island Press.

Powell, K.I., K. Krakos, and T.M. Knight.  2011.  Comparing the reproductive success and pollination biology of an invasive plant to its rare and common native congeners: a case study in the genus Cirsium (Asteraceae).  Biological Invasions 13: 905-917. (PDF)

Crone, E., E. Menges, M. Ellis, T. Bell, P. Bierzychudek, J. Ehrlen, T. Kaye, T.M. Knight, P. Lesica, W. Morris, G. Oostermeijer, P. Quintana-Ascencio, A. Stanley, T. Valverde, T. Ticktin, J. Williams.  2011. How do plant ecologists use matrix population models?  Ecology Letters 14: 1-8. (PDF)

Knight, T.M., K. Havens and P. Vitt. 2011. Will the Use of Less Fecund Cultivars Reduce the Invasiveness of Perennial Plants? BioScience 61: 816–822. (PDF)

Burns, J.H., Ashman, T.-L., Steets, J.A., Harmon-Threatt, A., and T.M. Knight. 2011. A phylogenetically controlled analysis of the roles of reproductive traits in plant invasions. Oecologia 166: 1009-1017. (PDF)

Beaton, L.L., VanZandt, P.A., Esselman, E.J. and T.M. Knight.  2011.  Comparison of the herbivore defense and competitive ability of ancestral and modern genotypes of an invasive plant, Lespedeza cuneata. Oikos 120: 1413–1419. (PDF)

Pardini, E.A., Drake, J.M. and T.M. Knight. 2011. On the utility of population models for invasive plant management: response to Evans and Davis.  Ecological Applications 21: 614-618. (PDF)

Powell, K.I., Chase, J.M. and T.M. Knight.  2011.  A synthesis of plant invasion effects on biodiversity across spatial scales.  American Journal of Botany 98: 539-548. (PDF)

Dangremond, E. M., E. A. Pardini, and T. M. Knight. 2010. Apparent competition with an invasive plant hastens the extinction of an endangered lupine. Ecology 91: 2261-2271. (PDF)

Loayza, A. P. and T.M. Knight.  2010.  Seed dispersal by pulp consumers but not legitimate seed dispersers increases population growth of Guettarda viburnoides in a neotropical savanna.  Ecology 91: 2684-2695. (PDF)

Law, W., J. Salick and T.M. Knight.  2010.  The effects of pollen limitation on population dynamics of snow lotus (Saussurea medusa and S. laniceps, Asteraceae): Threatened Tibetan medicinal plants of the eastern Himalayas.  Plant Ecology 210: 343–357. (PDF)

Buckley, Y.M., S. Ramula, S.P. Blomberg, Burns, J.H., E.E. Crone, J. Ehrlén, T.M. Knight, J.B. Pichancourt, H. Quested, G.M. Wardle.  2010.  Causes and consequences of variation in plant population growth rate: a synthesis of matrix population models in a phylogenetic context. Ecology Letters 13: 1182-1197. (PDF)