Defining ecologically relevant vessel parameters in Quercus robur L. for use in dendroecology: a pointer year and recovery time case study in Central Germany

Abstract

The most promising and representative earlywood vessel parameters were identified for dendroecological applications in oak. Recent improvements of methods used in tree-ring and quantitative wood anatomical studies have helped to widen the selection of parameters which contain environmental information. In the present study, we identified the most promising parameters with respect to signal strength, representativeness, and applicability in oak (Quercus robur L.) from two sites in Germany with different moisture regimes. We analyzed three tree-ring and 15 vessel parameters. Principal component analysis was used to detect clusters of relatively similar parameters. Correlation analysis and classical dendrochronological methods were used to select the most robust parameters. From the 15 initial anatomical parameters, six proved to be suitable for tree-ring anatomical studies based on our screening criteria. These were mean area of the vessels of the first row, mean of the five largest vessels, total vessel area, total area of the vessels excluding the first row, vessel density, and total vessel area as a percentage of tree-ring area. These parameters were applied to samples to search for lagged responses to positive and negative pointer years using superposed epoch analysis. Negative, i.e., dry, pointer years provoked no lagged changes in analyzed parameters at either site; whereas positive, i.e., moist, pointer years showed a lagged negative response of all parameters, which was more pronounced at the drier site.