Spatial Clustering of False Ring Anomalies in Juniperus Virginiana of the Oklahoma Cross Timbers

Abstract

This study counted false rings in eastern redcedar (Juniperus virginiana) samples to track growing conditions in the Cross Timbers of Oklahoma. Using ArcGIS, this study expands on previous research that used comparison between two sites and examines trends across the Cross Timbers region of central Oklahoma. Kriging analysis was used to compare atmospheric data from the Oklahoma Mesonet to tree core data. False rings are a type of growth anomaly that occurs in certain species of trees, particularly evergreens. These anomalies result from periods of water stress that cause the tree to begin forming late wood, followed by late season precipitation that causes the tree to revert to its normal growth pattern. False rings can indicate areas prone to a high degree of climatic variation. The highest occurrence of false rings was found on the boundary between the driest and wettest regions. These areas were not subjected to prolonged periods of drought, but did experience some degree of water stress. This may be useful in identifying areas prone to sudden shifts in growing conditions and providing greater seasonal resolution of dendroclimatic models. This trend was the strongest with vapor deficit, where the highest and lowest levels produced almost no false rings, but the mid-range levels produced large quantities of false rings. False ring probabilities were tracked using 553 samples from eastern redcedars growing in eleven sites throughout central Oklahoma. The false ring records counted in these cores were compared to weather records collected through the Oklahoma Mesonet. Maps of weather averages were constructed using Kriging analysis on records from 1994 to 2008.