Characteristics of the Keystone Ancient Forest Preserve, an Old-growth Forest in the Cross Timbers of Oklahoma, USA
Stacy L. Clark
Stephen W. Hallgren
David W. Stahle
Thomas B. Lynch
The Cross Timbers forest ecosystem may contain some of the most extensive tracts of remnant old-growth forests in eastern North America, but has gone largely understudied and unprotected. We described three old-growth stands in a 50-ha old-growth forest located in the northeastern portion of the Cross Timbers region in Osage county, Oklahoma. All stands were dominated by two oak species, Quercus stellata (Wangenh.) and Q. marilandica (Muenchh), which were self-replacing under their own canopy. Age structure analysis revealed that Q. stellata has been continuously recruiting in each stand for over 200 years. Juniperus virginiana (L.) was rare in the overstory, but was the longest-lived species (> 400 years old). In one stand, this species may be increasing in abundance and we attribute this to a seed rain from surrounding cedar-invaded fields. Total coarse woody debris was relatively low (2.1-9.2 m3/ha) compared to other midwestern forests, probably due to the small stature of the dominant trees and recent occurrence of fire. Quercus stellata did not conform to traditional models of population structure for old-growth stands. The models could not account for the reduced aggregate crown area and tree density at smaller diameter classes. The lack of fit to traditional models of stand structure, that have been based on shade-tolerant late successional species, was indicative of the episodic recruitment processes of oaks, a shade-intolerant, early successional species. Results from this study expand traditional definitions of old growth and, thus, will heighten awareness for conserving these unique and unprotected ecosystems.
Repeat Photography in the Ancient Cross Timbers of Oklahoma, USA
R. Daniel Griffin
David W. Stahle
Matthew D. Therrell
The Cross Timbers form the broad ecotone between the eastern deciduous forest and the grasslands of the southern Great Plains. Forests in the Cross Timbers are dominated by low stature, non-commercial oaks that have not been systematically logged and may be one of the least disturbed forest types in the eastern United States. Here we used long-term repeat photography to document 20th century landscape change in the Cross Timbers, highlighting the persistence of old-growth forest on steep uplands. We repeated 23 historical (1902-1934) landscape photographs of the Oklahoma Cross Timbers from the U.S. Geological Survey’s photographic archive in this study. We also investigated the modern forest conditions to identify the presence of old growth. The four photographic pairs presented here do not fully represent the 20th century history of vegetation change in Oklahoma, but these figures vividly illustrate some of the major landcover changes in this forest prairie ecotone: (1) many pre-settlement old-growth forest remnants survive on rugged escarpments in this region, (2) large reservoir projects on the Arkansas, Cimarron, Canadian, and other rivers have inundated vast areas of farm and rangelands, and (3) some range grasslands are being invaded by woody plants. This repeat photography study provides compelling visual evidence for the survival of ancient forest remnants in the Cross Timbers of Oklahoma.