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Fig. 4.1. Distributions of biomass for two cases: mm0 = 1 (solid line) and m 1 = 1.5 (dashed line).

Fig. 4.1. Distributions of biomass for two cases: mm0 = 1 (solid line) and m 1 = 1.5 (dashed line).

Analysis of data about the distribution of individuals in fish populations with respect to their biomasses using fishery statistics (Pritz, 1974; Lurie and Wagensberg, 1984) showed a good conformity of these empirical distributions with theoretical ones.

Let us consider the following hypothetical situation: an environment became more favourable in relation to a community, and its total equilibrium biomass M1 became bigger than its previous biomass M0. The change brought about an increase both in the total number and in the mean biomass of the community, so that m 1 > m0. In turn, this led to the change in distribution (5.7) (Fig. 4.1).

One can see that the growth of mean biomass increases the number of large individuals; the number of small individuals, on the contrary, decreases.

4.6. Information analysis of the global vegetation pattern

If we look at a standard botanical description of some territory, we can see that it contains, firstly, a list of species (types, forms, etc.) of plants represented in the territory, and secondly, the percentage of cover, pi, i.e. the percentage of the total territory covered by ith species. This is a typical linguistic construction, in which the alphabet of the corresponding language is formed by the names of all the species contained in the list. It immediately appears useful to apply information methods to its analysis, in particular to

Table 4.1

Different types of vegetation (biomes)

Table 4.1

Different types of vegetation (biomes)

1. Polar desert

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