Abstracts

Forest Ecosystems

Biogeochemical processes in forest ecosystems within the anthropogenic zones of South Pribaikalia and on the background regions, located in the coast zone of Baikal Lake, were studied. Investigations were carried out on the basis of conjugate testing soil profiles, forest substrates and different organs of birch (Betula pendula Roth) sampled from 60 stations. All samples gathered were analyzed by atomic emission, atomic absorption and x-ray fluorescence analytical techniques. Results of chemical analysis were used for producing the database, which became a basis for the development of biogeochemical criteria for estimating forest ecosystems. This paper gives results of x-ray fluorescence determination of Si, Al, Fe, Mn, Mg, Ca, Na, K, P, S, Cl and Sr in birch leaves. These quantitative characteristics of chemical element contents in plant organs were obtained without the sample decomposition.

Regular increase of contents of Si, Al, Fe, Cl and partially Sr and S in birch leaves within the man-made zones was established. This tendency agrees with the found accumulation of the above elements within upper soil horizons. The group of elements having high biohpility, namely P, Mn, K, is otherwise distributed in plant species and tends to accumulate in the plants growing in the background regions. As to Ca and Mg in birch leaves, their contents have insignificant variations and slightly depend on the plant habitat. Taking into account particularities of the above element behavior, the regularities of distribution of content ratios, namely Ca/Mn, Ca/P, Ca/Si and P/Al were considered for birch leave. These ratio analysis permits to establish well-defined regularities, which reflect nature of chemical element interactions. Antagonism of Al to P, as well as Si to Ca for forest ecosystems of man-made zones was clearly shown. Ca/Si and P/Al ratios regularly change their values depending on the man-made loading increase. Distribution of Ca/Si and P/Al values has the opposite tendency in comparison with the above one. These ratios increase in birch leaves gathered within anthropogenic zones. This fact indirectly points out to the depression of photosynthesis processes and violation of biogeochemical cycles of biophylic element migration. The broken state of forest systems is well traced by K/Na values in vegetation organs of high plants also.

Thus, the obtained regularities serve as criteria for ascertaining disbalance of biogeochemical cycles in plants of forest ecosystems and may also be used for estimating extent of their degradation.

Note. Abstracts are published in author's edition

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