Anthropogenic Influences on Vegetation Outside Central Europe

Human influences have changed the natural vegetation in all climatic regions and biomes. There are specific developments connected to the natural basis of plant growth as well as specific human influences. Examples have been chosen from three biomes showing the spectrum of possible consequences: the Mediterranean region, the dry regions of Africa (keyword "desertification") and the humid tropics of Africa (keyword "destruction of tropical forest").

Mediterranean Region

Plants in the Mediterranean region are particularly stressed because of the dry periods in summer, which may be of different length, but are always significant. The influence of fire must also be considered, an influence which has increased by human intervention. Tree species of Mediterranean forests in the lower and upper mountain zones, listed in the scheme of altitudi-nal zones in Fig. 4.1.23, are thus almost all drought resistant and stimulated rather than damaged by fire.

Land use affecting large areas started in the western Mediterranean region (bays of Alicante and Catalonia) in the early Neolithic about 7000 years ago (Badal et al. 1994; Riera-Mora and Es-teban-Amat 1994). The evergreen oak forests (Quercus rotundifolia) near the coast was intermixed with deciduous oaks (Quercus faginea, Q. pubescens) was thinned and shrubs which demanded more light (heliophilic shrubs) occupied the area. Typical Mediterranean shrub communities, the macchie, developed. Inland areas remained untouched for a long time, disregarding the first transhumance, e.g. shepherds moving in the hot, dry summers from the plain into the mountains near the coast, and establishing a "vertical" migratory pattern of grazing management. The farms on the coastal plain, with favourable soils and availability of water, e.g. the Spanish "huertas", were the first areas with intensive agricultural crops. Evidence of crop plants introduced from the Mediterranean into North Africa demonstrates the development of an increasingly richer flora in the agriculturally managed landscapes (Le Floch et al. 1990). In the Palaeolithic period barley (Hordeum vulgare) was evident, in the Neolithic period wheat (Triti-cum spp.) emerged as well as fruit trees (Phoe

semihumid-humid zonation sequence

Altitudinal zone

semiarid-arid zonation sequence

Reforestation with

Natural vegetation

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