J I

Relatively unnatural

Distant from nature

Unnatural

Artificial

Relatively unnatural Distant from nature

Artificial

Half-natural unnatural Artificial

Mesohemerob Beta-

Euhemerob Alpha-

Polyhemerob species that are successful in this sequence decreases with each new step. Plants must possess the characteristics listed in Table 4.1 3 in order to be successful.

The classification of vegetation according to the "degree of naturalness" has also differed. The most important differences are compared by Dierschke (1984; Table 4.1.4). It is now assumed that the proportion of agriophytes in vegetational units correlates with the degree of human influence. Therefore, it is possible to determine, quantitatively, the degree of human influence (degree of hemeroby) in a unit of vegetation by the proportion of agriophytes and neophytes and the loss of indigenous species (Table 4.1.5).

Bornkamm (1980) uses the classification by Sukopp (1972) for planning of land use. The proportion of neophytes increases with the loss of indigenous species (Fig. 4.1.20). He also reconstructed the distribution of land with the same degree of hemeroby for two Bavarian villages during the course of historical development and was able to demonstrate the increasing human influence (Fig. 4.1.21).

Recently, the consequences of gain and loss of species on the indigenous vegetation have been discussed. The loss of barriers to distribution leads to mixing of the flora and fauna from various bioareas. Elton (1958) regards this as a decisive, recent change in the biosphere. Two marked historical epochs must be distinguished: the time after the discovery of America up to the sixteenth century with increasing possibilities for travel between continents, and the time from the nineteenth century when new anthro-

Table 4.1.5. Proportion of neophytes and loss of native species related to the degree of human interference (hemeroby). (After Sukopp 1972)

Proportion of neophytes

Loss of native vascular plant species (per 1000 km2)

Ahemerob

Oligohemerob

Mesohemerob

Euhemerob

Polyhemerob

Metahemerob

pogenic sites opened up for the establishment of plants.

Lohmeier and Sukopp (1992) analysed the consequences of introduced foreign plants on the actual vegetation and present ecosystems in Europe, and Jäger (1988) gave percentage and absolute figures of synanthropic species worldwide (Fig 4.1.22). In industrial countries about 100 species per 100,000 km2 are naturalised, but there are exceptions such as the 800 species in Japan, where three floral regions meet. Lövei (1997) has shown (Table 4.1.6) that the proportion of synanthropic species has increased since the research by Jäger. Sukopp (1972) assumed fewer than 1% of introduced plants, but, according to Lövei (1997), this has increased to 6%. Sukopp (1972) considered that 54% of naturalised species in Germany originate from Europe itself and west Asia, 30% from areas with moderate climates in North America, 9% from central and east Asia. From these values of distribu-

Fig. 4.1.20. Schematic relationship between type of land use and classification of human influence, also called hemeroby (after Bornkamm 1980). % H Proportion of total land surface under particular types of human influence (hemeroby); % G proportion of a particular hemeroby class in the total landscape area. Surface use: I industry; V transport; 5 settlement; E recreation; L agriculture and gardens; F forestry; N nature reserves (see also Table 4.1.5)

Fig. 4.1.20. Schematic relationship between type of land use and classification of human influence, also called hemeroby (after Bornkamm 1980). % H Proportion of total land surface under particular types of human influence (hemeroby); % G proportion of a particular hemeroby class in the total landscape area. Surface use: I industry; V transport; 5 settlement; E recreation; L agriculture and gardens; F forestry; N nature reserves (see also Table 4.1.5)

before 1200

before 1200

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