The role of disturbance in the co‐existence of the evergreen Quercus ilex and the deciduous Quercus cerrioides

Abstract

Question: Which is the response of the evergreen Quercus ilex and the deciduous Q. cerrioides to repeated disturbances? Location: central Catalonia (northeastern Spain), in the areas affected by two of the largest historically recorded wildfires in NE Spain: the Bages‐Berguedà fire (24 300 ha forested area burned in July 1994), and the Solsonès fire (14 300 ha burned in 1998). Methods: Survival and growth of individuals of Quercus ilex and Q. cerrioides were evaluated in plants subjected to different fire histories and experimental disturbances (burning, cutting or clipping) applied either before or after summer. Results: Survival was high (> 99%), with both species showing a similar high resistance to disturbances. Growth after experimental disturbance was positively related to the size of the individual before the latest forest fire occurred. Fire history had a large effect on resprout growth, as the repeated incidence of disturbances lowered the capacity of individuals to grow. The type and season of experimental disturbance experienced by plants had a large effect. Individuals that experienced total above‐ground loss had lower growth rates than those with partial loss. A similar pattern was observed in individuals disturbed after the summer in relation to those disturbed before summer. Conclusions: The larger growth rates recorded in Q. cerrioides across all fire histories and experimental treatments, and the higher vulnerability of Q. ilex to increased fire frequency, intensity of experimental disturbance, and disturbance season, provide evidence for the relatively high susceptibility of the latter to repeated disturbances. This view disagrees with the larger resilience of this species compared to co‐existing deciduous oaks, as reported.

Fire-driven oak regeneration in French Mediterranean ecosystems

“…multistemmed individuals without clear apical dominance and with evidence of top killing and resprouting. The resprouting of oak recruits is assumed to result from various disturbances such as fire and predation (Bonfil et al, 2004), but also from shading under the closed canopy of mature woodlands . Suckers (shoots rising from a root) probably exist but the distinction was difficult and thus inaccurate.…”

History matters: Previous land use changes determine post-fire vegetation recovery in forested Mediterranean landscapes

“…Quercus sp) will be short-distance passively dispersed and will require some degree of previous perches and vegetation shelter to ensure effective biotic dispersal and further establishment (Gómez et al, 2008;Gómez-Aparicio et al, 2009;García et al, 2010;Zamora et al, 2010), which implies a slower colonization rate in open areas (such as crops recently abandoned). However, once established, these species will be highly resilient to fire occurrence, as post-fire natural regeneration is usually guaranteed by resprouting from protected buds, thus maintaining the same individualś density in the burnt area (López-Soria and Castell, 1992;Espelta et al, 2003;Bonfil et al, 2004).…”

Aboveground and belowground biomass allocation patterns in two Mediterranean oaks with contrasting leaf habit: an insight into carbon stock in young oak coppices

“…The higher investment in photosynthesizing tissues over woody tissues may allow Q. cerrioides to have higher photosynthesis rates during the spring months (Quero et al 2006), which ultimately results in the ability of this oak to keep a higher relative growth rate in comparison with Q. ilex (Espelta et al 2005(Espelta et al , 2006(Espelta et al , 2012Cotillas et al 2009). Conversely, the lower leafiness of Q. ilex would be responsible for the lower growth rates observed in that species (Bonfil et al 2004), but also reduced water transpiration, which may be a key trait to overcome summer water stress and repeated drought episodes, typical under Mediterranean climate (Sanz-Pérez et al 2007). In fact, when analysing the linear relationship between total leaf area and basal area (Fig.…”

“…Interestingly, the scaling exponent (b) of the allometric equations did not differ significantly between Q. ilex and Q. cerrioides. Since these two oaks coexist in a wide area of their common distribution rank along the Mediterranean Basin (Bonfil et al 2004), this result suggests that evolutionary pressures may be acting to maintain allometric relationships adapted to the biophysical trade-offs associated with the environment where they are found (Niklas 2006), resulting in converging life history traits and architecture (Valladares et al 2002). In fact, some studies conducted at a worldwide level suggest that significant differences in the scaling exponent (b) of allometric equations appear only when comparing very distant taxons (e.g.…”

“…Both species resprout vigorously after disturbance and frequently coexist in mixed forests (Bonfil et al 2004). The disturbance regime experienced in the study area is typical for most Mediterranean oak forests, subjected to repeated fire events and traditionally managed through clearcutting to obtain firewood or charcoal (see Terradas 1999;López et al 2009).…”