Long-Term Broad-Scale Changes in Upland Oak Forests Throughout Oklahoma, USA
Event Website
http://www.nafew2009.org/
Start Date
6-22-2009 10:30 AM
End Date
6-22-2009 10:50 AM
Description
In this study, we present evidence of long-term, broad-scale changes in upland oak forests in south-central North America and compare these changes to those reported for other oak-dominated ecosystems. From 2007-2008, we re-sampled 30 forest stands originally sampled in the 1950s throughout the Cross Timbers of Oklahoma, USA. We compared basal area, tree density and sapling density between the sampling periods using paired t-tests and partial canonical (pCCA) and detrended (DCA) correspondence analyses to answer the two following questions: (1) How has the composition of undisturbed upland oak forests located throughout a large geographical area changed over five decades, and (2) What factors likely control widespread patterns of change in these forests? For the 60-year time period, our results indicated an increase in total and Quercus stellata basal area and tree density. However, Q. stellata and Q. marilandica sapling density decreased. Juniperus virginiana, an invasive native species, and species richness increased for all measures. DCA indicated that re-sampled stands generally changed from forests dominated by Q. stellata-Q. marilandica to forests with greater species richness and more J. virginiana. Although Q. stellata remained a dominant tree species, the composition shifted towards mesophytic forest species. Our results suggest that in the absence of fire, increased presence of an invasive native species (J. virginiana) coupled with the decline of oak species contributed to the conversion of oak-dominated forests to forests with less oak, more mesophytic species and greater species richness. These dynamics are consistent with those of oak-dominated forests worldwide.
Long-Term Broad-Scale Changes in Upland Oak Forests Throughout Oklahoma, USA
In this study, we present evidence of long-term, broad-scale changes in upland oak forests in south-central North America and compare these changes to those reported for other oak-dominated ecosystems. From 2007-2008, we re-sampled 30 forest stands originally sampled in the 1950s throughout the Cross Timbers of Oklahoma, USA. We compared basal area, tree density and sapling density between the sampling periods using paired t-tests and partial canonical (pCCA) and detrended (DCA) correspondence analyses to answer the two following questions: (1) How has the composition of undisturbed upland oak forests located throughout a large geographical area changed over five decades, and (2) What factors likely control widespread patterns of change in these forests? For the 60-year time period, our results indicated an increase in total and Quercus stellata basal area and tree density. However, Q. stellata and Q. marilandica sapling density decreased. Juniperus virginiana, an invasive native species, and species richness increased for all measures. DCA indicated that re-sampled stands generally changed from forests dominated by Q. stellata-Q. marilandica to forests with greater species richness and more J. virginiana. Although Q. stellata remained a dominant tree species, the composition shifted towards mesophytic forest species. Our results suggest that in the absence of fire, increased presence of an invasive native species (J. virginiana) coupled with the decline of oak species contributed to the conversion of oak-dominated forests to forests with less oak, more mesophytic species and greater species richness. These dynamics are consistent with those of oak-dominated forests worldwide.
https://digitalcommons.usu.edu/nafecology/sessions/adaptive_ecology/1