Crosstimbers (Quercus stellata and Quercus marilandica) forest has dominated the landscape of Oklahoma for centuries, seemingly unchanging.  However, the scientific community is beginning to notice changes in oak forests across the world. We initiated a study in 1998 to assess long-term dynamics of a crosstimbers stand.  In the Tallgrass Prairie Preserve in northern Oklahoma, we tagged and mapped all trees greater than 2.5cm DBH, (7,683 total) in a 4 ha site.  We resurveyed the stand in 2008 to assess growth, mortality, and recruitment.

Results/Conclusions

Our results demonstrate that the stand is decidedly not in steady state.  While 1,683 trees died, there were only 5 new stems found in 2008 (all Q. stellata). Q. marilandica experienced double the mortality of Q. stellata (40% compared to 20%), and the size class distribution is shifting towards larger trees. We also saw a size dependant mortality effect at both the smallest and largest classes.  Although the drivers of the dynamics are unclear, the current study adds to a growing number of case studies worldwide indicating dramatic changes in oak forests.