Effect of site quality and shading on sprouting patterns of holm oak coppices

Sprouting is its main regeneration mechanism of holm oak (Quercus ilex) forests after disturbance. This study analyzes the variability of the sprouting ability of holm oak in plots located in the lower and upper parts of the slope (as a factor determining site quality in the study area), and with or without shading (two different shade conditions produced by cutting and removal (or not) of burned stems after a fire). Results obtained in this study show that position in the slope (which indicates, at least partially, site quality) is a key factor on size differentiation of sprouting holm oak individuals. Thus, individuals of lower-position plots are higher and larger than those of upper-position plots, and these differences between plots increase through time. Shading of sprouting stools has no effect on stool height growth, but affects crown surface, with a significant increase in full-light stools compared to shaded ones. Although initial rapid growth in height has been considered a key factor determining competitive advantages after disturbance, our results suggest that the pattern of horizontal occupation of space is also a fundamental trait to explain medium- and long-term holm oak coppice structure. Although in holm oak, the persistence of the root system after disturbance has been used to explain the vigorous growth rates of sprouting individuals, in this study, pre-fire size of individuals correlated poorly with the size of the stool after disturbance. This result suggests that some variables considered in this study, such as stool height, are more dependent on other factors which are variable at the stand level.