Co-ordinating Editor: Dr. Kerry Woods.
Long-term directional changes in upland Quercus forests throughout Oklahoma, USA
Article first published online: 14 JAN 2010
© 2010 International Association for Vegetation Science
Journal of Vegetation Science
Volume 21, Issue 3, pages 606–618, June 2010
How to Cite
DeSantis, R. D., Hallgren, S. W., Lynch, T. B., Burton, J. A. and Palmer, M. W. (2010), Long-term directional changes in upland Quercus forests throughout Oklahoma, USA. Journal of Vegetation Science, 21: 606–618. doi: 10.1111/j.1654-1103.2010.01168.x
- Issue published online: 13 APR 2010
- Article first published online: 14 JAN 2010
- Received 19 December 2008; Accepted 14 December 2009.
Vol. 21, Issue 5, 1001, Article first published online: 16 JUN 2010
- Fire exclusion;
- Forest dynamics;
- Juniperus virginiana;
- Quercus marilandica;
- Quercus stellata;
- Species composition;
- Vegetation change
Questions: (1) How have the composition and structure of undisturbed upland Quercus forests changed over 50 years across a large region and moisture gradient; (2) What factors are associated with long-term and broad-scale changes in these forests?
Location: Oklahoma, USA.
Methods: We re-sampled 30 forest stands originally sampled in the 1950s across a large geographical area and compared basal area, tree density, and sapling density between the sampling periods using paired t-tests, CCA, and DCA. We examined vegetation dynamics in the context of drought indices compiled for the sample period.
Results: Total and Quercus stellata basal area and tree density increased, but Q. stellata and Q. marilandica sapling density decreased. Juniperus virginiana and woody species richness increased for all measures. DCA indicated that re-sampled stands generally changed from Q. stellata–Q. marilandica-dominated forests to forests with greater woody species richness and more J. virginiana. Q. stellata remained a dominant tree species; otherwise, composition shifted towards mesophytic and invasive woody species. Measurements taken in the 1950s immediately followed a major drought; whereas subsequent decades were significantly moister.
Conclusions: Fire exclusion and drought may have played an important role in driving changes towards lower dominance by Quercus, increased importance of mesophytic and invasive species, and greater woody species richness. These phenomena are similar to those found in Quercus-dominated forests throughout the northern hemisphere.