West european geobotanists approaches to typology and mapping of vegetation territorial units

Abstract

The relevance of this paper for Russian geobotanists is due to the fact that until recently the author had regularly come across the statement that the phytosociological approach cannot be used in vegetation mapping and in legends for the geobotanical maps. In my opinion, such attitude towards the potential of the generally accepted and most widespread phytosociological approach in world practice significantly impoverishes Russian geobotany. And more seriously, it significantly reduces the possibility of using modern technologies and international experience in the field of vegetation mapping. In this regard, the purpose of the paper is to characterize the modern approaches of West European geobotanists to the typology of territorial units of vegetation based on phytosociological methods and their application to the plant cover mapping at different scales. Some of the most important stages in the development of this approach in West Europe are also reflected in the paper. In 1928 J. Braun-Blanquet in his work “Plant sociology” proposed the main directions for studying the structure and composition of territorial units of vege­tation. In the 1970s R. Tüxen laid the foundations of symphytosociology and proposed a method for transforming the system of syntaxa into sigma-syntaxa, and J.-M. Géhu and S. Rivas-Martínez, defined sigmetum as the basic unit of symphytosociology. The phytosociology of a plant landscape is based on the allocation of sigma-associations — combinations of plant communities and their complexes within homogeneous landscape units, giving it physiognomic originality. In landscape phytosociology, two main directions are currently distinguished: symphytosociology, with sigmetum (series, sigma-association) as main typological unit and tesela as territorial one, and geosymphytosociology with geosigmetum (geoseries) and catena, respectively. Thus, landscape phytosociology uses concepts that differ depending on the level of landscape organization: the level of series, or sigmetum (permaseries, curtaseries and, directly, series), and the level of geoseries, or geosigmetum — geopermaseries, geocurtaseries and geoseries). Each series/geoseries in relation to the water supply regime belongs to one of four types: climatophilic, tempohygrophilic, edaphoxerophilic, and edaphohygrophilic. Until the 1970s, only large-scale maps could be prepared on a phytosociological basis. They displayed homogeneous communities, predominantly of the association rank. Following the works of R. Tüxen, C. Beguin and O. Hegg, S. Rives-Martínez and J. M. Géhu, who substantiated the methodology of transforming the system of syntaxa into sigma-syntaxa based on phytosociological tables, sigmetum (series) and geosigmetum (geoseries) have become the main mapped units. It was during this period that a qualitative leap took place in geobotanical mapping, which made it possible to move from a large scale (1: 5–25 000), when communities of the association rank were highlighted on the map, to a smaller scale (1: 25–500 000), with the combinations (sigmetum and geosigmetum) and preservation of most of the releve information. France can be confidently attributed to the undisputed leader in the field of mapping (Géhu, 1979; Ozenda, 1985; Delbosc et al., 2015, 2016, 2017, 2018; Loidi, 2017; etc.), where the classification of territorial units of vegetation and geobotanical mapping as the basis of the nature protection system were raised to the state level as national programs. In addition to France, the intensive development of these approaches is currently taking place in Italy (Blasi et al., 2000, 2005, 2007, 2010, 2014, 2017; Biondi et al., 2004, 2010, 2011, 2012, 2014; Blasi, 2016; etc.), Spain (Rivas-Marténez, 1976, 2005; Rivas-Marténez et al., 2014, etc.) and Portugal (Pinto Gomes et al., 2003, 2007; Raposo et al., 2016). Also noteworthy are the works of scientists from Germany (Schwabe, 1989, 1991, 1997, 1999) and Switzerland (Beguin et al., 1979; Theurillat, 1991, 1992; Beguin, 1998, 2003, 2009), which made a significant contribution to landscape phyto­sociology. Currently, we can say with confidence that in the countries of the European Union (EU) it is phytosociology­ that underlies the entire environmental system, including, first of all, the main legislative document of the EU on nature protection — Council Directive 92/43 / EEC or “Habitats Directive” (Commission …, 2003). The directive is largely based on the syntaxon set of plant communities, and the use of phytosociological terminology in the diagnosis and characteristic of habitats is often of key importance (Angelini et al., 2016). Since the approval of the Directive, phytosociology has actually been recognized as a basic science for the biodiversity management, which is reflected in the existence of a number of pan-European and national projects — Natura 2000, CORINE, EUNIS, CarHAB, etc., which are carried out and funded at the national and EU levels. On the basis of the principles and methods of landscape phytosociology in West Europe, approaches to geobotanical mapping are intensively developing, in which not only individual scientists and scientific schools, but also educational and government institutions (ministries, committees, departments, etc.) participate. National programs for classification and mapping of vegetation are formed and actually work. Based on this approach, over the past 2–3 decades, hundreds of vegetation maps of various scales have been prepared, covering both individual regions and provinces, and the territories of entire states. Fundamentally, this approach provides an excellent opportunity to combine the fundamental research results based on the latest achievements of phytosociology with their direct application in practice in the field plant cover monitoring, environmental protection and land use.