Dolomite flora of the Baetic Ranges glades (South Spain)

The vegetation growing on special types of rocks has long attracted the attention of botanists and ecologists. In this respect, interest in serpentine soils has led to the publication of a number of monographs on their flora and vegetation. The high levels of heavy metals, in particular of Ni, and the low proportion of Ca/Mg are generally held responsible for the severe restrictions limiting flora development on this kind of rocks. Although researchers have also studied other types of unusual bedrocks such as gypsum outcrops, little work has been done on dolomites. This is surprising because dolomites share certain features with serpentines (they are both rocks rich in Mg). This paper deals with the flora peculiar to the dolomites of the Baetic Ranges, one of the richest territories in Europe as far as flora is concerned. A number of botanists with experience in the study of this very particular flora have joined together to make a list of the plants peculiar to the dolomites. Our catalogue includes 144 species with a variable degree of “dolomitophily”, the score of which ranging from 1 to 3, the maximal value. A comparison of the taxonomical spectrum of this catalogue with the one found in territories where dolomites are dominant or with other areas of serpentines reveals that there is a given deviation or bias in favour of some families. A similar comparison between biotypes also leads to the observation that, as usually happens on ultramafic rocks, hemicryptophytes tend to be dominant on dolomites. In addition, we show that the proportion of Ca/Mg catalogued for different kinds of soils could be a key element in explaining the restrictions which dolomites and serpentines impose on plants. In dolomites this proportion shows an intermediate position (2.19) between soils derived from limestones (11.30) and serpentines (0.84) in the study area.