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THE EFFECT OF SAMPLE DRYING ON TREE RING ANALYSIS. Ing. Lukáš Dragoun UCOLIS 2012 Kostelec nad Černými lesy This contribution presents the statistical characteristics of dendrochronological analysis samples (of increment borers). The aim of this study is to clarify the changes of single spruce rings size caused by samples drying and to determine the accuracy of the used method using Image analysis in WinDENDRO program. The data from 92 spruce samples on anthropogenic soils in the Sokolov region were obtained and will be further specified. Because the data evaluation is rather time-consuming, the presentation contains partial results only but they will be processed and published later. The study was financed by the IGA fund Faculty of Forestry and Wood Science, project – Dendrochonological analysis on anthropogenic soils in the Sokolov region, no. 20124351 (43140/1312/3116). Basic questions: Does sample drying affect the size of samples and individual tree rings? Does the drying differ with varying position of tree rings in the sample? Does the change in portion of early and late width affect drying of individual tree rings? Sampling 98 samples were taken 51 samples were measured in dried condition Tree ring analysis Of damp samples Of dried samples Statistical data analysis Sample dampness Weight method Sample 73 72 A 72 B Average ring size 2,28 2,15 Standard deviation of tree ring 0,01 Number of tree rings 73 EARLY- 72 EARLYWIDTH WIDTH 2,12 1,33 1,68 0,04 0,03 0,04 0,1 34 33 30 34 33 Average sample size 75,3 71,1 63,5 45,3 55,5 Standard deviation of sample 0,06 0,22 0,17 0,25 0,58 Average dampness of the samples When taken away Damp samples Dried samples 45 % 38 % 8% There was a significant difference between damp and dried samples (T-test for Dependent Samples) and between individual tree rings (Wilcoxon Matched Pairs Test) Paired T-test: t=27,61, df=50; p < 0,01 Wilcoxon test: t=20366,5, p < 0,01 Tree rings are aligned to the core of sample For 10 cm of sample Mean Mean error Median Standard deviation Variance Minimum Maximum 3.24 0.09 3.19 0.67 0.45 2.07 5.01 Tree rings are aligned to the edge of sample Linear regression confirmed strong relationship between tree ring position in sample and drying out intensity. Model explains only low amount of variability. p < 0,01 R-squared = 0,013 It is evident, that big amount of remaining variation can be explained by other variables. There was a significant difference between damp and dried samples. paired T-test; t=27,61; df=50; p < 0,01 Wilcoxon test; t=20366,5; p < 0,01 Average tree ring size difference was 3 %. The position of tree ring in sample affect its drying out. Linear regression drying out % (y) = 3,9119 – 0,0346 * year (x) Tree rings remote 30 years between each other differ in drying out for 1 %. The relationship between drying out and early/late width were not tested due to high measurement error. This is an objective for subsequent research. Questions? ... References Statistical analyses were carried out in Statistica software. Thanks for help with statistical analyses to Ing. Daniel Zahradník, Ph.D. The study was financed by the IGA fund of Faculty of Forestry and Wood Sciences, project – Dendrochronological analysis on anthropogenic soils in the Sokolov region, no. 20124351