Introduction

Dendrochronological researches are valuable tools for the study of environmental changes (United Nations Conference on Environment and Development,1992; Lovelius, Komarova & Torfimova, 2009), in a long time and different spatial scales.

Detailed dendrochronological researches of the impact of climatic factors on the growth and spread of woody plants were conducted mainly on representatives of coniferous stands of Pinus sylvestris L. and Larix sibirica L. in forest-steppe zones of Altai (Magda, Oydupaa and Block, 2004).

Dendrohnological research of Betula pendula Roth in Kazakhstan has not been conducted. Due to the high information content of dendrochronological method, its conduct in the ecosystems of East Kazakhstan is very important. It is dendrochronological data over the long background can give an objective assessment of biotopes of Betula pendula Roth in East Kazakhstan.

Birch is common in different climatic zones, due to its significant ecological plasticity, which allows it to adapt to extreme environmental conditions. All this makes it convenient object of bioindication and identifying adaptation mechanisms. Research, conducted in the European North in birch forests, mostly were conducted with the taxation point of view by such scholars as Antipov, 1979; Kulagin, 1985; A.V.Glyzin. However, dendrochronological research of Betula pendula Roth in Kazakhstan has not been conducted. Therefore dendrochronological research of the Betula pendula Roth can be regarded as one of the promising areas for the assessment of environmental changes.

Therefore, research of the climate change impact on forest vegetation is quite natural. It is proved that radial increment of trees changes with the temperature factor change. Drawing up the regional dendroclimatic scales of natural variability of the trees radial increment in different forest conditions provides the basis for environmental monitoring of forest ecosystems.

Therefore, the paper’s objective is the selection and justification of appropriate methods for collecting and processing dendrochronological material of birch forest plantations in Kazakhstan.

Paper was based on results of field observations on sample plots and laboratory research.

Dendrochronological researches of birch were conducted in Russia and abroad by scholars such as;

Lewis, J., et al. studied Betula pendula Roth on heavy metals pollution, growing in two contaminated sites were evaluated to assess their capacity to phytoscreen and phytoremediate chlorinated aliphatic compounds and heavy metals. Both sites of industrial pollution in central Sweden. Silver Birch has demonstrated the potential for phytoscreen and possibly, phytoremediate and related compounds, but it did not demonstrate the ability to effectively phytoscreen heavy metals (Lewis, Qvarfort and Sjöström, 2015).

Smith A., et al. conducted assessment of the above-ground biomass for Betula pubescens and Betula pendula Roth in conditions of Norway (Smith, Granhus, Astrup, Bollandsås and Petersson, 2014).

Thomson A.M. et al. conducted comparative analysis of the chloroplast structure (f), DNA of Betula lenta L., B.lutea Michx, was concluded the impact of climate change on phylogeographical structure of these species in the Eastern and North America (Thomson, Dick and Dayanandan, 2014).

Bruce P. Dancik, Burton V. Barnes studied variability of morphology of B.lutea Michx to the environment. And also studied regularities of change of leaves taken at different sites, where birch grew (Barnes, Dancik & Sharik, 1974).

In 2011, in Tomsk T.A.Kuklinа conducted comparative phenological observations for Betula pendula and Betula pubescens at their joint growth and at sites with different environmental conditions, were defined conditions under which hybridization of species in urban and peri-urban plantations is possible (Kuklina, 2011).

A.A.Boyko (2005) revealed regularity of seasonal dynamics and the nature of adaptive reactions of Betula pendula Roth on various structural and functional levels of organization in a mixed type of environmental pollution (Boyko, 2005).

A.A.Grigoriev revealed features of the formation of forest stands of larch and birch in the highlands of the Nether-Polar Urals under the climate change impact and assessed their modern structure (Grigoriev, 2011).

G. Juady, G. Jacoby, R. D’Arrigo (1999) conducted reconstruction of trees increment and temperatures in the Northern Hemisphere in the XX century based on data on the variability of the width of annual rings in America, Scandinavia, Siberia and Mongolia. Revealed limiting of the trees growth in many northern habitats due to the observed warming. (Juady, Jacoby and D’Arrigo, 1999).

Numerous dendrochronological researches on woody plants were conducted by Choymaa Dulamsuren. Were investigated water relations of Siberian larch, which showed that trees of forest-steppe zone of northern Mongolia and Saur mountains often suffer from drought. Water supply of trees growing on mountain ridges of forest-steppe zone is heavily dependent on the current rainfall, since the roots are not in contact with groundwater (Dulamsuren, Hauk and Bader, 2012; Dulamsuren, Wommelsdorf, Zhao, Xue Ya, Zhumadilov, Leuschner and Hauck, 2000; Dulamsuren, Hauck and Leuschner, 2010; Dulamsuren, Hauck, Khishigjargal, Leuschner and Leuschner, 2010; Dulamsuren, Hauck, Leuschner and Leuschner, 2011).

Also, in recent years, effect of anthropogenic factors on woody plants were examined with dendrochronological methods.

In particular, E.D. Lobjanidze and M.D.Gabunia (2000) found that man-made pollution leads to early cessation of cambial activity, reduced radial increment and autumn-wood content in annual rings (Lobjanidze, Gabunia, 2000).

B.S. Mazeppa proposed a method for comparing the actual radial increment with an increment in “pre-anthropogenic” period with extrapolation for the future period based on identified regularities of forest increment (Mazepa,1986).

Currently, a large number of dendrochronological researches are devoted to comparison of correlation between individual climatic factors and trees increment in order to predict tree increment, reconstruction and forecast of climate dynamics and identification of the leading factors in the formation of the width of anuual rings.

Significant material in the study of pathological formation of Juniperus Sibirica in the annual rings is contained in the paper of R.M. Hantemirov, L.A. Gorlanova, S.G. Shiyatov, which allowed the reconstruction of the frequency and intensity of extreme cooling during the vegetation season in the last 600 year.

So in the article of Ye.V.Koltunov, M.I.Khamidullina “Trends in the dynamics of the Betula pendula Roth radial increment and parameters of entomoresistance” contains analysis that in plantations with low entomoresistance amplitude of radial oscillations of increment was significantly higher compared to that of high entomoresistance.

Paper of M.V.Skomarkov, Ye.A.Vaganov, K. Wirth, A.V.Kirdyanov contains results of dendroclimatic research of annual rings of spruce, fir, pine, birch and aspen growing in the middle taiga subzone of Central Siberia. Identified common features of the variability of annual rings in conifers (spruce and fir) and hardwood (birch and aspen) species. Ye.A. Vaganov, M.K. Hughes, A.V. Shashkin, M.K. Arbatskaya showed the efficacy of the dendrochronological method for the analysis of components of the carbon balance in the various stages (Vaganov, Kruglov & Vasiliev , 2008).

The study area is located in the Katon – Karagai State National Natural Park of East Kazakhstan. Here focused a rich diversity of flora and fauna, as well as preserved species listed in the Red Book of Kazakhstan. According to preliminary data, more than 2,000 species of vascular plants grow on the natural park.

Forests, which are the main heritage of Natural Park occupy 34% and represented mainly with conifers. These are spruce, Siberian pine, larch and fir, birch and aspen, as well as a wide variety of shrubs and dwarf shrubs.

Borders of Katon – Karagai State National Natural Park include: the southern macro slopes of the ridges Listvyaga and Katunsky (southern and eastern slopes of Belukha city node), the western part of the high plateau Ukok within Kazakhstan, ridges Southern Altai, Tarbagatai and Sarymsakty.

Complex mountain terrain causes a wide variety of climatic conditions, profound climate change undergo with the rise up from the foot of the mountains to the tops of them. The climate is sharp continental, with large variations in temperature, as in seasons, and for days. Winters are long and cold. Hot summer day is replaced with a cold night. Precipitation is unevenly distributed, the largest amount falls in summer (June, July), and the minimum in January and February. Annual rainfall is 432 mm. The average annual air temperature is + 1,6°C with an absolute maximum of + 34°C and an absolute minimum of -44°C. The average depth of soil freezing in Katon-Karagai is 67 cm. The average annual wind speed is 3.8 m/s.

Analysis of the annual trees increment is widely used inpaleogeographic, archaeological, hydrological, astrophysical, geobotanic, forestryandpaleoclimaticreconstructions (Rinn ,1996).

Researches carried out based on annual trees increment have a high time resolution, making them sources for dynamic analysis and evolutionary processes in the elements of the biosphere.

Methods

Methodology dendrochronological research

Main principles and laws in dendrochronological research: the law of limiting factors, the principle of sites and habitats selection, sensitivity principle, the principle of cross-dating use, the principles of replication and uniformity  (Lobjanidze, Gabunia, 2000). Woody plants that grow within the climatically homogeneous region, by incremental value similarly respond toХ changes in climatic limiting factors. In favorable climatic conditions most of the trees have formed wide annual rings, and in unfavorable – narrow. In this regard, the trees growing in the similar climatic conditions show synchronous variability of increment through the time. Especially indicative are narrow rings, which are formed when increment is limited to the greatest extent in some climatic factor (Matskovsky and Solomina, 2011).

During field expeditions in 2013 in East Kazakhstan samples of larch, birch, fir, pine, cedar, aspen, and spruce were selected from 10 sites. A total of 600 cores were taken. Sampling was conducted according to standard procedure adopted in dendrochronology (Vaganov, Kruglov and Vasiliev , 2008).

Dendrochronological research technique was described by many scholars such as S.G.Shiyatov, F.H.Schweingruber, H.C.Fritts, E.R.Cook and L.A.Kairiuksnis. In this work this technique was used in its classical form.

The method works in the forest

Wood samples (mainly birch, further larch, spruce, fir, cedar) for each site were selected on a limited area (20х20m). This method allows the use of trees that grow within a given area or uniform area. In this case, the tree-ring chronologies maximally contain information on the variability of conditions within the boundaries of the site. The coordinates of the selected sites were recorded using a Global Positioning System (GPS). All samples of living trees were collected with incremental borer (Pressler increment borer) with an outer diameter of 10 mm and an inner diameter of 5 mm. This mechanism allows extracting core sample from wood with a diameter of 5 mm and a length of 10-40 cm with all the annual rings without harming the tree. Samples were taken at 1.3 m from the surface at an angle of 90º. Obtained samples were placed in special paper containers with an inner diameter which exceeds 2-3 mm of the sample core diameter, thus guaranteeing cores safety while transporting. All core samples were marked and described (number, diameter, tree height, competition).

Before transporting the collected core samples were dried in the field to air-dry condition to the surface of the wood core is not covered with mold. Collected wood samples were transported in a metal container to prevent breakage ( Solomina, Dolgova and Maksimova , 2012).

Results

Processing lab

Further work with wood samples was carried out in laboratory conditions.

Cores were glued onto a wooden base, which is a rectangular shaped rail of about 1 cm in width and height and a length slightly greater than the length of the core sample, then were signed in accordance with the code of each sample.

Core surface was cleaned with sharp cutting tool. In our case, we cleaned the core with a microtome. To increase the contrast, core samples were stained with a solution of safranin and overwrote with chalk. Then, knowing the exact date and year of sampling, conducted a preliminary dating of rings (Matskovsky and Solomina, 2011).

Annual ring – a layer of wood that formed in one year as a result of the cambium activity in the vegetation period, consisting of a layer of early (light part of loose wood) and late (more dark and dense) wood (Solomina, Dolgova and Maksimova , 2012).

To carry out dendrochronological studies we used deciduous species (diffuse-porous wood, representatives of the genus Betula, Populus). From coniferous species used those that are more responsive to changes in external conditions, prevalent in areas of cold and temperate climate, durable and have a clearly distinguishable annual rings of forest growth (representatives of the genusa Pinus, Picea, Larix, Abies,) (Cook  and  Kairiukstis,1990).

Measuring the width of annual rings.

The width of the annual rings was measured with accuracy of “+ -” to 0.01mm on semi-automatic installation LINTAB-6.0 (Shiyatov, Vaganov, Kirdyanov, Kruglov, Mazepa, Nauryzbaev and Hantemirov, 2000).  The installation consists of a stereomicroscope, measuring table, through which core is uniformly fed in the direction of measurement, as well as computer as a storage of measured data. The value of the annual rings width is fixed automatically by a computer program, in this case, the program TSAP-Win (Time Series and Analysis Presentation – analysis and cross dating of dendrochronological series and graphical representation of the processed data results).

The main advantage of dendrochronological reconstructions is their reliable up to one year timing. Therefore, they are chronological benchmarks for other series of indirect climate data, none of which can be compared with dendrochronology dating accuracy( Solomina, Dolgova and Maksimova , 2012).

Figure №1 shows the chronology of the annual rings width on Betula pendula Roth.

Figure 1: Standard chronology of the annual rings width of Betula pendula Roth Click here to view full figure

Table 1: Location of sampling sites in Katon – Karagai State National Natural Park

Figure 2: Location map of sampling points. Click here to view full figure

Discussion

Increasingly, tree-ring chronologies are used in the reconstruction of the weather conditions, climate, as well as monitoring studies. In this connection, conduct of dendrochronological researches in Kazakhstan is very relevant and may be a promising direction for environmental assessment. Just this method can provide an objective assessment of biotopes of birch plantations in the area.

This article contains the preliminary research of Betula pendula Roth in the forest steppe of East Kazakhstan.

Collection of data in amount of 600 cores for dendrochronological analysis was conducted. Cameral treatment of the material was conducted, also material was processed on semi-automatic installation LINTAB-6.0. Using TSAP-Win program was conducted absolute dating of each individual tree-ring series with respect to the remaining cores.

To date, all core samples of birch, larch, pine, fir and cedar were processed, but due to the complexity of dendrochronological research, currently we are working on the analysis of the resulting material.

Further analysis and work will be presented later.

Сonclusion

This article shows the preliminary study on birch (Betula pendula Roth.) In the forest of East Kazakhstan.

When analyzing the dynamics of growth of tree rings birch was taken into account age trend. It is established that a clearly marked age trend in the dynamics of growth, expressed in absolute units (mm) – one of the important characteristics of a healthy stand. The results showed that in the birch forest stands of East Kazakhstan intensive hyperbolic decline in growth observed up to 30 – 40 years of age, followed by a smooth decrease as tending to the horizontal line.

Thus, dendrochronological research methods birch are promising avenue to explore the possibility of climate change in Kazakhstan. And also can be used to assess the ecological status of ecosystems during the monitoring research and survey work.

Acknowledgments

All the data presented in this paper were conducted  within the research project “The impact of livestock on forest regeneration and biodiversity on the border of forest steppe in the mountains of Altai and Khangai in a contrasting development of livestock in Mongolia and Kazakhstan , carried out between Germany, Kazakhstan and Mongolia” under supervision of Dr. Ch. Dulamsuren. All scientific work was done in the dendrochronological laboratory of the Department of Plant Ecology of Georg-August Gottingen University, as well as in the dendrochronological laboratory of S.Toraigyrov Pavlodar State University under the direction of Dr. Ch. Dulamsuren.

We express our deep and sincere appreciation for the invaluable assistance to the Dr. Choimaa Dulamsuren and Prof. Dr. Markus Hauck.

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