Thomas J. Givnish

 

Henry Allan Gleason Professor of Botany and Environmental Studies

Ph.D. (1976) Princeton University • 315 Birge Hall • 608-262-5718 • givnish@wisc.edu

Plant ecology and evolution; adaptive radiation and molecular systematics;
phylogeography; physiological ecology; landscape dynamics

Conservation Biology – Don Waller, Ken Cameron, Ken Sytsma, and I, supported by a new $3M grant from NSF Dimensions of Biodiversity, are studying the morphological, ecological, genetic, and phylogenetic determinants of local plant loss and invasion in Wisconsin, with a view to explaining patterns observed by Waller’s lab and mine over the past 50 years, and to predicting new changes over the coming century.  Recensuses of forests, prairies, and pine barrens originally sampled by JT Curtis in the 1950’s provide unparalleled insights into past losses and invasions.  Ongoing studies of several dozen morphological traits will, we hope, shed light on the bases for these losses and invasions.  A molecular phylogeny including all native and introduced plant species will provide the basis for phylogenetically structured analyses of the observed changes, as well as helping lay the groundwork for a phylogeny of all plant species in North America and the broader ecological and comparative studies that it would facilitate.  Finally, we are quantifying C values for several hundred dominant species, as a proxy for the “tempo” of their life history, and inferring the spatial scale of genetic differentiation and gene flow within species, as proxies for the mobility of different species and their susceptibility to inbreeding “death spirals”.








John Volin, Paul Glaser, and I are investigating how spatially coupled feedbacks help create and maintain the patterned landscape characteristic of the central Everglades.  Over the coming decade, the United States plans to spend several billion dollars to help restore the Everglades by modifying hydrological flows. However, current models for the outcome of such modifications generally ignore the fundamental importance of feedbacks in shaping peatlands. We are developing a model that incorporates spatially coupled feedbacks among vegetation, substrate, hydrology, biogeochemistry, and landforms, and asks how these feedbacks should contribute to the self-assembly of patterned landscapes under different flow regimes. 

We are testing the resulting predictions using stratigraphy, measurements of production, decomposition, hydrology, and biogeochemistry, and highly detailed GIS analyses in four different regions of the Everglades with radically different flow regimes, imposed by the emplacement of various water-control structures over the past 50 years. We hope to integrate our findings with landscape-level hydrological modeling by the USGS, South Florida Water District, and the National Park Service to predict the impact of different restoration scenarios on the patterning, biodiversity, and community- and landscape-level functioning of the central Everglades.

My students and I also study the ecology of a variety of endangered plant species and communities, focusing on the dynamics and determinants of species loss in some systems, and characterizing the ecological features of others needed for their successful conservation and restoration.

 

Photographs:  TOP - Portrait of the scientist as a young man among Nymphaea; false-color satellite image of the central and southern Everglades, showing patterned landscape with streamlined tree islands and a series of water-control structures constructed over the last half-century; Gentiana puberulenta (Gentianaceae), one of the short-statured, small-seeded species that has undergone a massive decline in prairie remnants over the past several decades; and Ken Wood, Steve Perlman, and I ascending a waterfall in remote windward Kaua`i, searching for an extremely rare lobeliad.


© 2011 University of Wisconsin Department of Botany

Last updated: 27 November 2011