[Quantitative estimation of the dynamics of adventive flora (by the example of the Tula region)]

The rate of enrichment of the Tula region flora with adventive species was quantitatively estimated taking into account the changes of their degree of naturalization during the last 200 years. Numerical score of degree of the naturalization for each species was used to compile the initial database: "0", species absent from the territory; "1", ephemerophyte; "2", colonophyte; "3", epecophyte; "4", argiophyte; "?", lack of data. Non-interpolated integral index of the dynamics of adventive flora NI(t) was calculated from this database. This index displays the sum of the degrees of naturalization of all the adventive species in the flora in some particular year. The interpolation of the initial database, aimed at minimizing the influence of random factors (e.g., gaps in observations or different activity of the researchers in different years), was performed by substituting the "?" symbol by a series of intermediate values based on studies of the data for adjacent territories. Interpolated integral indices I(t) were calculated from the interpolated database. These indices were then leveled out with Morlet wavelets, in order to distinguish random spikes (lasting less than 50 years) from the analyzed signal, and thus approximate the index dynamics to the objective trend that represents the dynamics of the flora and not the rate of activity of the researchers. The dynamics of the adventive flora of the Tula region revealed with this method shows the following facts: 1) average rate of the enrichment of the adventive flora with strange species has been constant for these 200 years and amounted to 15 species per decade; 2) average rate of naturalization was relatively low and constant, amounting to 5 species per decade; 3) fluctuations of the composition and naturalization degree of the Tula region adventive flora species were not shown to be dependant directly on the changes in the territory's economic development during the last two centuries; 4) no periodicity was recorded in the advent of new species, and the fluctuations of the number of adventive species can be attributed to the fluctuations of research intensity.