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