Plants on Rich-Magnesium Dolomite Barrens: A Global Phenomenon

Abstract

For botanists and ecologists, the close link between some plants and substrates, such as serpentine or gypsum, is well known. However, the relationship between dolomite and its flora has been much less studied, due to various causes. Its diffuse separation from limestone and the use of a vague approach and terminology that, until now, no one has tried to harmonize are among these reasons. After carrying out an extensive review, completed with data on the distribution of plants linked to dolomite, the territories in which this type of flora appears at a global level were mapped using a geographic information system software. In addition, data on soils were collected, as well as on their influence on the ionomic profile of the flora. These data were completed with the authors’ own information from previous research, which also served to assess these communities’ degree of conservation and the genetic diversity of some of their characteristic species. The results showed that the so-called “dolomite phenomenon” is widely represented and is clearly manifested in the appearance of a peculiar flora, very rich in endemisms, on dry soils, poor in nutrients, and with a high Mg level. Although dolomite habitats cause adaptations in plants which are even more recognizable than those of other rock types, they have not been widely studied from an ecological, evolutionary, and conservation point of view because, so far, neither their characteristics nor their universal demarcation have been precisely defined.

Elementome of Endemic Dolomitic Flora: Pterocephalus spathulatus (Lag.) Coult

“…The extension of dolomitic rocks covers broad areas [14], from the White Mountains in USA, to areas in the Mediterranean Basin, where the Betic Mountain Ranges [19,20], the Taurus Mountains [21], the Balkans [22], the Alps [23], Crete [24], etc., are worthy of special attention, in addition to some areas of Asia, such as Anatolia, Tibet and the Himalayas, although there are no excessively specific references [25], and in the southern hemisphere, where their distribution extends through the southern part of Africa, Australia, and Tasmania [26].…”

“…However, they cannot always be easily differentiated from limestones. This has made it difficult to study the vegetation and flora associated with dolomitic outcrops [14]. Therefore, it is a complicated task, since there is a wide variety of habitats, to the point where up to seven rocky environments can be distinguished which have vegetation associated with dolomite presence [8].…”

“…According to Mota et al [14], there are a number of characteristics common to this type of soil that contribute to determining the phenomenon of dolomitophily. First, dolomitic soils are characterised by being poorly developed, and by their sandy or burdensome appearance due to the fragmentation and disaggregation of the bedrock.…”

“…In the case of dolomite, perhaps the most striking of all, the flora is dominated by upholstery species, endowed with a dense sericeous indumentum, which literally covers the ground although in a dispersed way. Interestingly, this type of vegetation is reminiscent of typical plant communities on coastal dunes due to its appearance or physiognomy [14], with serious conservation threats [15,16]. Coastal dunes and dolomitic soils, often also referred to as "sandy" soils, share a coarse texture that does not have a large capacity to retain moisture.…”

“…These factors influence the water economy of plants through evotranspiration and the amount of light received. In addition, the micro-relief is responsible for generating heterogeneous spaces in which the availability of water and nutrients can vary enormously [8,[11][12][13][14]17].…”