62
Josep Maria Espelta, Santiago Sabate and Javier Retana
(Chap. 3). To understand their current structure as well as to predict their
dynamics, it is necessary to have a complete view of the main features involved in the resprouting process of holm oak. Forest regeneration through
resprouting is considered a complex phenomenon involving different organization levels (Ford and Newbould 1970; Pysek 1991; Riba 1991), the development and dynamics of sprout cohorts (ramets) being a basic process
whereby the later fate of individuals (genets) and, hence, of the whole population are determined. In this chapter we describe the resprouting process in
holm oak stands after the most common disturbances, scaling up from the
morphological and physiological traits of sprouts (the sprout level), through
the dynamics of sprouts on the stool (the stool level) and finally to the consequences for the forest structure and its maintenance (the stand level).
5.2 Resprouting Response of Holm Oak after Disturbances
Holm oak (Quercus iIex 1.) resprouts vigorously after disturbances, with
sprouts occurring by activation of dormant buds located in the stump, the
root-crown or to a lesser extent the roots (Lobreaux 1987; Giovannini et al.
1992; Retana et al. 1992). The resprouting vigour of holm oak after disturbance is much higher than that observed in other Mediterranean resprouters
(Lopez Soria and Castell 1992). Moreover, mean number of sprouts per stool
after cutting holm oak trees (Fig. 5.1A) is also higher than in other Quercus
species, such as Q. coccinea, Q. prinus and Q. velutina (Ross et al. 1986), and
Q. alba, Q. falcata and Q. stellata (Lowell et al. 1987). The high resistance of
holm oak to disturbances through resprouting has been argued as one of the
main causes explaining the spread of this species allover the western Mediterranean Basin 8000 years B.P. (Pons and Quezel 1985). According to different authors (see Romane et al. 1988), this expansion was probably driven by
intense management combining fire, coppicing and domestic livestock, which
involved in large areas the substitution of other Quercus species by holm oak.
A good example of the aforementioned potential of holm oak to resprout
is provided by the words of V. de Larminat, a French forester who defined
this species in 1893 as "resistant for centuries to all types of man-caused
disturbance". Notwithstanding this optimistic view, we know that not all
holm oak trees resprout after disturbances, with the causes of mortality being basically related to three types of major influences: (1) the source, intensity and season of disturbance, (2) edaphic and climatic factors, and (3) the
size (and probably age) of individuals.
Although we lack comparative studies addressing the influence of disturbance type on the likelihood of holm oak individuals to resprout, Table 5.1
provides the ranges of holm oak mortality after four kinds of disturbances in
separate studies. In all cases, survivorship through resprouting is higher than
Josep Maria Espelta, Santiago Sabate and Javier Retana
(Chap. 3). To understand their current structure as well as to predict their
dynamics, it is necessary to have a complete view of the main features involved in the resprouting process of holm oak. Forest regeneration through
resprouting is considered a complex phenomenon involving different organization levels (Ford and Newbould 1970; Pysek 1991; Riba 1991), the development and dynamics of sprout cohorts (ramets) being a basic process
whereby the later fate of individuals (genets) and, hence, of the whole population are determined. In this chapter we describe the resprouting process in
holm oak stands after the most common disturbances, scaling up from the
morphological and physiological traits of sprouts (the sprout level), through
the dynamics of sprouts on the stool (the stool level) and finally to the consequences for the forest structure and its maintenance (the stand level).
5.2 Resprouting Response of Holm Oak after Disturbances
Holm oak (Quercus iIex 1.) resprouts vigorously after disturbances, with
sprouts occurring by activation of dormant buds located in the stump, the
root-crown or to a lesser extent the roots (Lobreaux 1987; Giovannini et al.
1992; Retana et al. 1992). The resprouting vigour of holm oak after disturbance is much higher than that observed in other Mediterranean resprouters
(Lopez Soria and Castell 1992). Moreover, mean number of sprouts per stool
after cutting holm oak trees (Fig. 5.1A) is also higher than in other Quercus
species, such as Q. coccinea, Q. prinus and Q. velutina (Ross et al. 1986), and
Q. alba, Q. falcata and Q. stellata (Lowell et al. 1987). The high resistance of
holm oak to disturbances through resprouting has been argued as one of the
main causes explaining the spread of this species allover the western Mediterranean Basin 8000 years B.P. (Pons and Quezel 1985). According to different authors (see Romane et al. 1988), this expansion was probably driven by
intense management combining fire, coppicing and domestic livestock, which
involved in large areas the substitution of other Quercus species by holm oak.
A good example of the aforementioned potential of holm oak to resprout
is provided by the words of V. de Larminat, a French forester who defined
this species in 1893 as "resistant for centuries to all types of man-caused
disturbance". Notwithstanding this optimistic view, we know that not all
holm oak trees resprout after disturbances, with the causes of mortality being basically related to three types of major influences: (1) the source, intensity and season of disturbance, (2) edaphic and climatic factors, and (3) the
size (and probably age) of individuals.
Although we lack comparative studies addressing the influence of disturbance type on the likelihood of holm oak individuals to resprout, Table 5.1
provides the ranges of holm oak mortality after four kinds of disturbances in
separate studies. In all cases, survivorship through resprouting is higher than