Tomáš Kolář

Radial Growth and Health Condition of Norway Spruce (Picea Abies (L.) Karst.) Stands in Relation to Climate (Silesian Beskids, Czech Republic)

Radial Growth and Health Condition of Norway Spruce (Picea Abies (L.) Karst.) Stands in Relation to Climate (Silesian Beskids, Czech Republic) The research was conducted in selected spruce stands of the Silesian Beskids aged over 70 at altitudes from 403 m a.s.l. to 794 m a.s.l. in 2008. The samples were taken and processed in compliance with standard dendrochronological methodology. Tree rings were measured and the tree-ring curves were synchronized using the PAST4 application. The age trend was removed in the ARSTAN application and the climatic influences were modelled in the DendroClim application. The regional standard tree-ring chronology shows an obvious decrease in the radial increment from the beginning of the 1970s to the mid-1990s. The gradual increase in radial increment which followed in the second half of the 1990s was interrupted in 2000, 2003, and 2006. Most of the years with the decreased radial increment have been confirmed by the analysis of significant negative years. The radial increment statistically significantly correlates with the precipitation in July and September of the previous year, precipitation in June of the year in question and precipitation during the vegetation period. Moreover, the growth of spruce is statistically significantly affected by temperatures in October of the previous year and March of the year in question. Additionally, the paper includes habitual monitoring of trees and the volume of salvage cutting in these districts. The condition of the habit of trees and the development of salvage cuttings agree with the hypothesis about strong stress load or its considerable increase in 2003 and the following years.

Extreme Radial Growth Reaction of Norway Spruce Along An Altitudinal Gradient in the Šumava Mountains

Extreme Radial Growth Reaction of Norway Spruce Along An Altitudinal Gradient in the Šumava Mountains Extreme radial growth reactions were analyzed over a 79-year period (1922-2000) to compare response of Norway spruce (Picea abies [L.] Karst.) along an altitudinal gradient (376-1221 m a.s.l.) in the Šumava Mountains, the Czech Republic. Extreme growth events were defined as pointer years, when an average percentage of the site pointer years reached at least 50% strength observed at the relevant altitudinal zone (low < ca. 700 m; middle ca. 700-950 m, high > ca. 950 m). The comparison of the pointer years showed a specific pattern for altitudinal zones (Low: negative pointer years 2000, 1992, 1984, 1976, 1971 and positive 1997, 1975, 1960, 1949, 1932, 1926; middle: negative 2000, 1992, 1976 and positive 1997, 1989, 1978; high: negative 1996, 1980, 1974, 1965 and positive 1989, 1963, 1927). Negative pointer years were usually induced by summer drought at low elevations and by wet-cold summer at high altitudinal zone. These two main limiting factors were probably combined at the middle altitudinal zone. Detailed understanding of the extreme tree ring pattern along the altitudinal and geographical scale may be used as one of the additional indicators of dendrochronological dating and provenance identification of spruce sample among altitudinal zones in the Šumava Mountains.

The Benefits of Tree-Ring Curves Detrending for Dating Archaeological Wood

The Benefits of Tree-Ring Curves Detrending for Dating Archaeological Wood During the process of developing the standard chronology for oak for the Czech Republic, two versions of standard chronology were determined: the standard chronology developed using detrended tree-ring series and the standard chronology developed using non-detrended tree-ring series. These standard chronologies were applied to date detrended and non-detrended average tree-ring curves obtained from dendrochronological samples from selected archaeological locations. The highest values of the t-test were achieved when comparing the detrended or non-detrended average ring curves only and exclusively with the detrended standard chronology. Similarly, the highest percentage of the curve parallelism was always obtained in comparison with the detrended standard chronology. The confidence and, more importantly, the prediction intervals of the detrended ring curves are considerably smaller than those of the non-detrended ones. The regression curves of the detrended standardised values of the ring curves are more similar to the calibration curve than the non-detrended ones. The significance level of the regression models in the detrended ring curves is notably higher, than in the case of the non-detrended ring curves. The differences established between the detrended and non-detrended standard chronology have highlighted the importance to develop detrended standard chronologies.

Dendrochronological and radiocarbon dating of subfossil wood from the Morava River basin

The paper deals with dendrochronological and radiocarbon dating of subfossil trunks found in the basin of the Morava River. The research into subfossil trunks had been conducted in the Czech Republic in the past but the research stopped in 2001. 160 records of measurements of subfossil, predominantly oak trunk samples, are preserved from that time. Three years ago the research was reopened and again the most trunks were found in the basin of the Morava River. 92 samples of oak trunks and 7 samples of other tree species (poplar, elm, maple, beech) were taken from selected sites. The samples were processed in compliance with the standard dendrochronological methodology. To date the samples, Czech, Austrian, Polish and German standard chronologies were used. In cases when the dendrochronological dating was unsuccessful, the samples were sent for radiocarbon dating. In total, 35 samples were dated, mainly by the radiocarbon method. Subfossil trunks from gravel pit Tovačov were dated and classified into 4 different periods, the oldest being from 2780–2190 BC. In Osek nad Bečvou, the samples were taken from two sites. Whereas from the 4 trunks taken in the river channel each was from a different period, the trunks from the gravel pit come from 981–1015 AD. The trunks found in the Morava River basin near Strážnice were dated to the 10th–15th century. In the future, we expect to extend the amount of the acquired samples with the aim to create a link to the existing standard chronology or to create a long floating average treering curve.

Exploring Growth Variability and Crown Vitality of Sessile Oak (Quercus Petraea) in the Czech Republic

Abstract Unraveling climatic effects on growth of oak - Europe’s most ecologically and economically important forest species - has been the subject of many recent studies; however, more insight based on field data is necessary to better understand the relationship between climate and tree growth and to adapt forest management strategies to future climate change. In this report, we explore the influence of temperature, precipitation and drought variability on the productivity and vitality of oak stands in the Czech Highlands. We collected 180 cores from mature oaks (Quercus petraea) at four forest stands in the Czech Drahany Highlands. Standard dendromethods were used for sample preparation, ring width measurements, cross-dating, chronology development, and the assessment of growth-climate response patterns. Crown vitality was also evaluated, using the modified ICP Forests methodology. Late spring precipitation totals between May and June as well as the mean July temperature for the year of ring formation were found to be the most important factors for oak growth, whereas crown condition was significantly affected by spring and summer drought. This study is rep-resentative for similar bio-ecological habitats across Central Europe and can serve as a dendroclima-tological blueprint for earlier periods for which detailed meteorological information is missing

Updating the Czech Millennia-Long Oak Tree-Ring Width Chronology

ABSTRACT In recent years, a millennia-long oak tree-ring width chronology, consisting of 3194 samples from 387 locations, was developed in the Czech Republic. Despite the collection of such a huge dataset, the replication in the 19th Century was very low and the natural oak distribution in the Czech Republic was insufficiently covered by recent samples, especially in Western Bohemia. This study aimed to remove these weaknesses, which have limited the paleoclimatic potential of this dataset, and to determine the number of sapwood rings, which is crucial for dendrochronological dating. Therefore, new recent samples were randomly collected at numerous sawmills along the Czech-German border. The historical material was usually sampled using a Pressler borer from church belfry constructions traditionally made from oak. In total, 252 recent and 90 historical tree-ring width series were incorporated into the chronology. The newly built chronology cumulatively consists of 3536 series, which covers the continuous period of A.D. 352–2014. The resulting tree-ring width record shows robust signal strength and homogeneous coverage of the territory. We show that the number of sapwood rings is constant over time. Therefore, we recommend using an estimate of 5–24 sapwood rings for a more precise dating of historical wood findings in the Czech Republic.

Growth responses of Norway spruce (Picea abies (L.) Karst.) to the climate in the south-eastern part of the Českomoravská Upland (Czech Republic)

The research was conducted in selected 80- to 110-year-old spruce stands in the south-eastern part of the Českomoravská Upland at altitudes from 350 m a.s.l. to 465 m a.s.l. The regional standard tree-ring chronology shows very low increments for years 1974, 1976 and 1992. After 1992, there is a sharp rise in increments with a climax in 1997. Afterwards, increments gradually decrease, reaching minima in 2003 and 2008. The years with low increments were also confirmed by the analysis of negative pointer years when over 80% of the analysed trees responded by a sharp decrease in increment, mainly in years 1976 and 1992. We can usually find values of monthly precipitation or monthly temperature average which can explain or help explain these falls in the radial growth. The correlations of diameter increments with average monthly precipitation gain only positive statistically significant values, namely for the months of May, June, July and August of the particular year. The correlations of diameter increments with average monthly temperatures gain only negative statistically significant values, namely for the months of June, July and September of the previous year and January and August of the particular year. In the examined area there is a significant negative correlation between average temperatures and monthly precipitation in July, August and September. The results of the habitual diagnostics show that with respect to the climatic conditions the health condition of the monitored stands is relatively good. On average, the defoliation does not exceed the values ascertained in different territories of the Czech Republic.

Notes towards an optimal sampling strategy

Abstract Though the extraction of increment cores is common practice in tree-ring research, there is no standard for the number of samples per tree, or trees per site needed to accurately describe the common growth pattern of a discrete population of trees over space and time. Tree-ring chronologies composed of living, subfossil and archaeological material often combine an uneven distribution of increment cores and disc samples. The effects of taking one or two cores per tree, or even the inclusion of multiple radii measurements from entire discs, on chronology development and quality remain unreported. Here, we present four new larch (Larix cajanderi Mayr) ring width chronologies from the same 20 trees in northeastern Siberia that have been independently developed using different combinations of core and disc samples. Our experiment reveals: i) sawing is much faster than coring, with the latter not always hitting the pith; ii) the disc-based chronology contains fewer locally absent rings, extends further back in time and exhibits more growth coherency; iii) although the sampling design has little impact on the overall chronology behaviour, lower frequency information is more robustly obtained from the disc measurements that also tend to reflect a slightly stronger temperature signal. In quantifying the influence of sampling strategy on the quality of tree-ring width chronologies, and their suitability for climate reconstructions, this study provides useful insights for optimizing fieldwork campaigns, as well as for developing composite chronologies from different wood sources.