ASU SoLS Faculty: John M. Briggs

Dr. Briggs has been involved with the Konza Prairie Long Term Ecological Research project since 1984. He served as Program Director of Ecology at the National Science Foundation and was a Research Professor at Kansas State University before coming to Arizona State University in 1999.

We are investigating the following projects:

1. Ecosystems in Transition: Causes and Consequences of Dramatic Shifts in Growth Form Dominance. Worldwide, the structure and function of many ecosystems are in transition due to global changes in climatic means and extremes, increased atmospheric CO2, N deposition, alterations in land management, and the spread of invasive exotic species. In the tallgrass prairies of the eastern Great Plains, the expansion of shrub cover and forest encroachment into this grassland is a widespread phenomenon. This is a serious conservation concern since tallgrass prairie is considered an endangered ecosystem. Our overall objectives are to use a tallgrass prairie grassland ecosystem to evaluate the patterns, mechanisms and ecological consequences of an ecosystem in transition from a grassland to closed-canopy shrub/woodland. We will test hypotheses regarding the role that resource availability plays in woody plant expansion in grasslands. Evaluating this grassland-to-shrubland transition at levels from the leaf to the landscape will provide both the mechanistic specificity, as well as the large-scale generality, required for successful conservation efforts.

2. Long-Term Ecological Research in Tallgrass Prairie: The Konza Prairie LTER Program. A comprehensive long-term ecological research program is being conducted at the Konza Prairie LTER site in NE Kansas. Our central hypothesis is that fire, grazing and climatic variability are essential and interactive factors responsible for the structure and function of tallgrass prairie. In contrast to many other grasslands where ecological processes are constrained by chronic limitations of a single resource (e.g., water), organismic to ecosystem processes and dynamics in tallgrass prairie are products of spatial and temporal variability in multiple limiting resources (water, light, N). Variability in, and switching among, these primary limiting resource(s) are caused by both extant and historical fire, grazing and climatic regimes. As a result of this complexity, and because grazing and fire regimes are managed in grassland systems worldwide, data from the Konza Prairie LTER program have relevance not only for understanding this grassland, but for broader ecological issues such as stability-diversity questions and interactions between land-use, biodiversity and climate change.

3. The role of humans in structuring plant communities. Since my move to ASU, I have expanded my research program to include a new emphasis on the importance of human activities as drivers of ecological processes and patterns. This work centers on the CAP-LTER program (http://caplter.asu.edu) and the IGERT program in Urban Ecology at ASU (http://ces.asu.edu/igert/home.htm). In addition, I have began an collaboration with archaeologists in order to study the legacy of prehistoric and modern human land use in the newly designated Agua Fria National Monument north of the Phoenix basin. This desert grassland has experienced two intense pulses of human use in the past 750 years: a sizeable agricultural occupation in the 1300s and livestock grazing since the mid 1800s. A collaboration between archaeologists and ecologists to study the long-term legacy of prehistoric and modern human land use on the ecology of this desert grassland will accelerate our understanding of human-environment interactions.

Current Students

Brad Butterfield Ph.D., Plant Biology; Hoski Schaafsma Ph.D., Plant Biology; Jason Walker Ph.D., Plant Biology

Selected Publications

Walker , J.S. and J.M. Briggs. An object-oriented approach to urban forest mapping in Phoenix. Photogrammetric Engineering and Remote Sensing (in press)

Schaafsma, H. and J.M. Briggs. Hohokam silt capturing technology: Silt fields in the northern Phoenix basin. Kiva (in press)

Briggs, J.M., K. A. Spielmann, H. Schaafsma, K. W. Kintigh, M. Kruse, K. Morehouse and K. Schollmeyer. (2006). Ecology needs archaeologists: Archaeology needs ecologists. Frontiers in Ecology and the Environment 4:180-188.

Briggs, J. M., A. K. Knapp, J.M. Blair, J. L. Heisler, G. A. Hoch, M.S. Lett, J. K. McCarron. (2005). An ecosystem in transition: causes and consequences of the conversion of mesic grassland to shrubland. BioScience 55: 243-254.

Heisler, J.L., J. M. Briggs, A.K. Knapp, J.M. Blair and A. Seery. (2004). Shrub expansion in mesic grasslands of Central North America: an ecosystem in transition? Ecology 85: 2245-2257.

Heisler, J. L., J.M. Briggs and A.K. Knapp. (2003). Long-term patterns of shrub expansion in a C4-dominated grassland: fire frequency and the dynamics of shrub cover and abundance. American Journal of Botany 90:423-428.

Collins, S.L., S.M. Glenn and J.M. Briggs. (2002). Effect of local and regional processes on plant species richness in tallgrass prairie. Oikos 99: 571-579.

Hoch, G.A., J.M. Briggs and L.C. Johnson. (2002). Assessing the rate, mechanism and consequences of conversion of tallgrass prairie to Juniperus virginiana forest. Ecosystems 6: 578-586.

Briggs, JM, AK Knapp and BL Brock. (2002). Expansion of woody plants in tallgrass prairie: A 15 year study of fire and fire-grazing interactions. The American Midland Naturalist 147:287-294.

Briggs, JM, and AK Knapp. (2001). Determinants of C3 for growth and production in a C4 dominated grassland. Plant Ecology 152:93-100.

Knapp, AK, JM Blair, JM Briggs, SL Collins, DC Hartnett, LC Johnson, and EG Towne. (1999). The keystone role of bison in North American tallgrass prairie. BioScience 49:39-50.

Collins, SL, AK Knapp, JM Briggs, JM Blair, and EM Steinauer. (1998). Modulation of diversity by grazing and mowing in native tallgrass prairie. Science Volume 280, Number 5364 pp. 745 - 747.

Knapp, AK, JM Briggs, DC Hartnett, and SL Collins. (1998). Grassland Dynamics: Long-term Ecological Research in Tallgrass Prairie. Oxford University Press, New York, 364 pp.