Paleopalynology and dendroclimatology, as the methods bioindication climatic and landscape change in the past.

Blyakharchuck T.A., Nesvetaylo V.D., Tartakovsky V.A.

Institute of Monitoring of Climatic and Ecological Systems

The natural archive of the information concerning a landscape and climatic changes in the past annually increases or accumulates natural objects. To open and to read this archive the special bioindication methods exist. Among these ones paleopalinology and dendroclimatology are advanced in Institute of Monitoring of Climatic and Ecologic of Systems. Paleopalinology allows to restore retrospective picture of vegetation changes in the investigated territory during the analysed interval of time on a basis of qualitative-quantitative researches of pollen spectra structure disputes consecutive deposit layers of lake or peat. A number of special mathematical methods helps to restores the quantitative characteristics of climate in the past on the basis of modern and fossil pollen data. For this kind of reconstruction in the institute’s database there are quantitative data of pollen series represent schematically covering complete Holocene and late numerous radiocarbon of date from Western Siberia and Altai. Some of them were used for quantitative climatic paleoreconstructions by a method of V.A. Klimanov.

Picture 1

The lake deposits cores from the upper border of the forest in Altay Republic

Picture 2

Pollen grains of the lake deposits

Picture 3

Part of the pollen diagram for the Kendegelukol Lake in Altay Republic

Dendroclimatology deals also with researches of climatic changes being a part of a complex method of dendrochronoindication of various natural and anthropogenic processes. The essence of this method consists in disclosing of dependence of tree annual rings characteristics from the environment factors to receipt the retrospective information concerning processes and phenomena defining a dynamic of these factors. Paleoclimatic changes have been established in rings of a tree morphometrically (in changes of the width of tree rings, section area, form of rings), in structure changes of tree cells, amount of ones, the thickness of cells walls, changes of physical and chemical characteristics of tree rings (e.g. density and reflecting ability of wood, elementary, biochemical, isotopic structure of wood. The researches in the above-stated directions are carried out in Institute and are issued in the local and international literature. They include data from various areas of Western and Central Siberia. The new methods assessment of climatic changes are kept to develop. Time ranges are used with dendroclimatological methods vary from one to hundreds and thousand of years.

Diagram 1

Dendrochronoindication

DirectionsDivisions

Dendrochronology

DendroclimatologyDendrochronoindication of natural processes and eventsDendrochronoindication anthropogenic influence

Morphometric dendrochronoindicationStructural dendrochronoindicationPhysicochemical dendrochronoindication

But as any other separate method all above mentioned ones have their own restrictions which do not allow unique interpretation of observable changes. The combination of paleopalinological and dendroclimatological methods allows to show both cyclic changes of a climate and general landscape changes amplifying the compelled fluctuations of parameters and deleting influence of the local factors. These two methods mutually add each other. Dendroclimatology mainly deals with short cycles of time but paleopalynology views the long-time tendencies in development of a climate and landscape. Amplitude and intensity of climatic fluctuations can also be established by a combination from these two methods. So if the few years duration cycles established in tree rings reflect climatic fluctuations within the limits of tolerance of this concrete tree than thousand years’ cycles reflected in the pollen diagrams by change of one type of vegetation by other one show deep climatic fluctuations were following with significant reorganizations of landscape.

For more exact disclosing of climatic fluctuations using bioindicational methods it is necessary to choose so-called informational points and objects which are more sensitive to climatic changes than another. In paleopalinology these ones are lakes and peat deposits from zones of transition ecotones such as forest-tundra, forest-steppe and timberland as well as of area situated far from strong influence of steady cyclones and anticyclones. Paleopalynological research in such areas (e.g. mountains of Altai and northern forest-tundra) were executed by the scientists of Institute

In dendroclimatology the most perspective trees for research of climatic fluctuations are those ones which grow in areas borders, in zone of ecotones and in high and low mountains timberlines.

Picture 5

Larix sibirica rings structure from Tunguska event center

Picture 6

Relative growth of Pinus sylvestris roots in comparison with summer (June - July) precipitation

Picture 7

Pinus sylvestris rings width dynamic (high bog of Samous lake-bog system)