Abstracts

Evolution of Species and Ecosystems: Theoretical Analysis and Computer-Assisted Modeling

The last decades of the previous century had global heating as their "motto" and were marked by the growing contrast of natural phenomena and processes all over the planet. Numerous researchers pointed out the fact that in higher latitudes the tendency of heating is likely to be harsher and may cause serious changes in the structure and seasonal rhythm of northern ecosystems. In fact, the increase of average air temperature by 0,3 - 0,9^оC during the period of 1960s-1990s is typical for the majority of meteorological stations located to the north from 600 n.l., mostly due to a significant warming in winte and spring. Also it is confirmed by the increase of soil tempeature for different depths by 0,5-1,2^оC in Arkhangelsk, Hoseda-Hard and Kandalaksha regions during 1960s-1990s (Vidyakina, 2000). Accordingly, the trends of frostless period increase and the shortening of stable snow cover period; the debacle of rivers tends to happen ealier; the annual pecipitation amounts increase slightly.

However, the phenological trends of Russian plain ecosystems dynamics for the same peiod are not that clear. The analysis of the data of seasonal rhythms observations shows the fact that the most significant shift of dates is characteristic for the early- and middle-spring phenomena in the life of trees. Now in the European North of Russia, the common birch leaf unrolling starts 5-10 days earlier, bird cherry breaking into bloom - 10-15 days earlier (compared with 1960). Mountain ash breaking into bloom starts about 5 days ealier (compared with the same period), but only in the noth-eastern region. The end of common birch leaf-fall happens 0-5 days later. At the same time the terms of starling arrival and first cuckoo's cry had almost no alterations and, vice versa, even tend to happen later (Minin, 2000).

Similar ambiguous tends of the biota reaction to the changes of climate are registered by the results of complex researches in natural reserves. For example, in Pechora-Ilych natural reserve we detected the tendency of, (1) on the one hand, widening of areas of bird and amphibian spieces and fixing earlier dates of spring phenomena and, (2) on the other hand, vegetation period shortening and fixing earlier dates of autumn phenomena during the last decades of the 20th century (Bobretsov et al., 2001).

Thus, the seasonal rhythms of most populations of the Russian plain had significant changes during the last decades, expressed in the direct shift of some phenophases starting dates. But even these shifts had different directions. A considerable shift of spring phenophases of a certain spieces (e.g., birds arrival) is not accompanied by alterations in autumn phenophases of the same spieces (e.g., starting date of migration of the same spieces of birds). The periods of birds stay and plants vegetation demonstrate tendencies of both widening and shortening (as in Pechora-Ilych natural reserve). At the same time, visual alterations of some natural phenomena had no effect on their dynamics. We may suppose that the process of the adaptation of populations (of both spieces structure and seasonal characteristics) and ecosystems on the whole takes place, and the accumulation of inconspicious changes may lead to a spasmodic swing of a system (in this case, of a biota) to a new statement (Vedyushkin et al., 1995).

We consider that the monitoring of changes in ecosystem seasonal rhythms is necessary in this situation. In order to control the process and take grounded decisions in the sphere of ecology and nature-protecting, we should develop a mass phenological observation network on the base of existing networks and organize new points of collecting and analysis of phenological information and including its in ECONET.

Note. Abstracts are published in author's edition

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