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Age (years)
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Introduction
Fig. 1.9. Biomass growth with age in four evergreen-sclerophyllous woody species (Paraskevopoulos et al. 1994).
the type and intensity of grazing pressure. Grazing changes the age structure
of the canopies and forces younger plants to develop in a limited space
around the paternal plant. It further results in stronger intraspecific competition among above-ground plant parts. Plants respond by modifying their
schedules of biomass allocation, maximising efficiency of nutrient turnover,
and increasing growth rates. In general, plant phenology, plant growth, biomass allocation, mobilisation and translocation of biomass and nutrients
between different plant parts, nutrient and water uptake, amino acid concentration, etc. synchronise with seasonally oscillating variables (see Arianoutsou-Faraggitaki 1979; Pant is 1987; Papatheodorou 1996, among many
others). Stamou and Pantis (1995) suggested that most of the plants dominating deteriorated Mediterranean areas fall into the competitive-ruderalstress tolerant (C-R-S) class of Grime's adaptive strategies. With regard to
growth strategies, woody plants can be classified on a linear continuum. One
endpoint of the continuum is occupied by fast growing, high risk, competitor
plants, whilst closer to the other endpoint the low growing, low risk, stress
tolerant plants are classified (Fig. 1.9). The former are most numerous in
areas under low grazing pressure associated with infrequent fire, while the
latter dominate in areas subject to intensive exploitation (overgrazing or frequent fires; Paraskevopoulos et al. 1994).