| Over the years, the poor quality timber produced by the stressful site conditions that characterize the Cross Timbers ecosystem has prevented most significant logging operations. The rugged terrain and poor soils have also protected many areas from agricultural clearing. As a result, many large patches of ancient forest remain scattered throughout the region. While post oak (Quercus stellata) and blackjack oak (Quercus marilandica) dominate most Cross Timber woodlands, isolated stands of shortleaf pine (Pinus echinata) can also be found This research focuses on an old-growth mixed oak-shortleaf pine stand in east-central Oklahoma found notably west of the continuous native distribution of this species. The basal area (17.2 m2/ha) and density (559.6 trees/ha) of this undisturbed forest stand is similar to other ancient Cross Timbers forests. With the exception of shortleaf pine, the composition of this stand is very similar to other undisturbed Cross Timbers forests as well. Shortleaf pine's regeneration appears to be supported by episodic recruitment pulses that are related to the frequent droughts that affect this region of the southern Great Plains. The pine appears to be of natural origin, but is a relatively recent colonizer in the region and may be part of an 18th/19 th century range expansion of shortleaf pine. |
