Vegetation complex
A vegetation complex (Sigmetum, Sigma society) is a specific section of a landscape that is characterized by a specific, recurring and thus typical combination of plant communities . The scientific description of the vegetation of vegetation complexes is provided by sigma sociology , a sub-discipline of plant sociology .
Similar to a plant society that displays site conditions in a certain area, a vegetation complex reflects the combination of ecological conditions in a more or less extensive site mosaic. Determining "factors" are relief, soil types or influences of the user such as mowing or (with the help of animals) grazing.
method
In many cases, one can find the same combinations of different plant communities in a certain landscape, which can be described as a vegetation complex. These plant communities in an area can be mapped using the plant-sociological method. When describing vegetation complexes, in addition to the “socialization of plant communities”, individual elements such as stone bars, willow trees, even huts or types of use such as vineyards with piles are included. At an even higher level, vegetation complexes can be combined to form geocomplexes (geosigmets). A socialization of plant communities is called a sigmetum.
Earlier approaches
Already Robert level man has on the Swabian Alb recognized such periodic vegetation patterns, which he called Steppe Heath called. Russian and Scandinavian vegetation experts such as Tichon Alexandrowitsch Rabotnow , Aimo Kaarlo Cajander , Hugo Osvald or Gustaf Einar Du Rietz have also pointed out that vegetation structures and societies can be summarized in higher units.
The founder of sigma sociology, which aimed to systematically process vegetation complexes , was Reinhold Tüxen, who also formulated the proposal to hierarchize the units of the vegetation complexes (sigma syntaxa) in a similar way to the plant communities.
Angelika Schwabe-Kratochwil and Hartmut Dierschke made important practical and theoretical contributions to the study of vegetation complexes .
Examples
Vegetation complexes can e.g. B. include an alpine pasture or the mountain forests of a valley flank. A well-known example is the typical sequence of different plant communities on a lake shore. Depending on the depth of the water or the degree of moisture of the soil, different sociologically defined societies form there, which can be described as a complex. The respective trophic still water types have their own defined vegetation complexes.
Further examples are vegetation complexes , which can be described by the typical combination of distinct plant communities of moors , or river and stream-accompanying plant communities and their vegetation complexes in low mountain ranges.
Vegetation complexes can also be recorded on a smaller scale, e.g. B. on paths and in an urban context.
Basic variants
According to Hartmut Dierschke, there are two basic approaches:
Systematic approach In ecologically homogeneous parts of the landscape, the existing plant communities are first recorded. Then similarities in the combination of plant communities are compared and, if they exist, summarized and a system built up inductively (= sigma syntaxonomy). Basic unit: the Sigmetum (sigma association, e.g. Stellario-Alneto-Sigmetum). In accordance with the Braun-Blanquet system, the higher units are designated as Sigmion (Sigma association), Sigmetalia (Sigma order) and Sigmetea (Sigma class).
The systematic approach is only suitable for so-called serial vegetation complexes (with a homogeneous recording area). In serial complexes the elements are subject to the same soil and climatic factors and are members of the same succession line, e.g. B. forest, forest mantle, perennial border and adjacent meadow.
With the natural-spatial approach , the vegetation complexes are first recorded and mapped as the basis for a natural-spatial structure (geo-synsociology). The recording of the plant communities is based on certain spatial units or given surface grids. As a result, summarizing complex types are also included here, which are then combined into larger complexes, the so-called geosigmets.
This approach can be used for serial and catenal vegetation complexes , with a catena denoting a vegetation complex with different vegetation potential . A typical example is the zoning of the soil and vegetation around an island in a river with strongly fluctuating water levels and, in addition, varying amounts of runoff. Max Moor has described a gravel island in the Rhone in the canton of Valais , on which the associated plant communities develop under different site conditions. They are:
- Gravel area with no vegetation in the often flooded lower embankment
- Alluvial-fireweed corridor on gravel and sand at the next higher level
- Lavender Willow Society on Sand
- above it the seldom flooded ridge with gray alder forest on sand
- and finally a willow-tamarisk corridor on silt.
Application examples
In practice, the description of landscape sections with the help of vegetation complexes is helpful in many ways.
- Large-scale structuring of growth climates or of cultural and natural landscapes can be made.
- With the help of vegetation complexes, habitat patterns that are used by certain animal species (e.g. birds) can be expressed.
- Vegetation complexes can provide excellent services for recording and comparing in the context of environmental impact assessments
- Vegetation complexes are in some cases suitable for determining the biodiversity in a landscape section.
- The intensity of anthropogenic influence in a landscape can be recorded and determined with the help of vegetation complexes.
literature
- Frey, Wolfgang and Rainer Lösch: Textbook of Geobotany. Plant and vegetation in space and time . 2nd Edition. Spektrum Akademischer Verlag, Munich 2004, ISBN 978-3-8274-1193-8
- Dierschke, Hartmut: Plant Sociology. Basics and methods. 683 S. Ulmer, Stuttgart. 1994
- Hard, Gerhard: The spontaneous vegetation of residential and commercial quarters in Osnabrück. In: Osnabrücker Naturwissenschaftliche Mitteilungen; Vol. 9, pp. 151-203, 1982 & Vol. 10, pp. 97-142, 1983.
- Hard, Gerhard: Vegetation complexes and neighborhood types in some northwest German cities. In: Landscape and City; 18 (1); Pp. 11-25.
- Kienast, Dieter: The spontaneous vegetation of the city of Kassel as a function of building and urban structure types of districts. Urbs et Regio 10; Kassel 1978: 411 pp.
- Kratochwil, Anselm and Angelika Schwabe: Ecology of communities: biocenology; 756 pp. - Stuttgart, Ulmer, 2001.
- Moor, Max: Plant communities of Swiss floodplains. - Mitt. Switzerland. Rst forest. Experimental 34, 221-360. Beer, Zurich. 1958.
- Wilmann, Otti: Ecological Plant Sociology : An Introduction to the Vegetation of Central Europe . 6., rework. Ed., Quelle & Meyer, Wiesbaden 1998 ( full text )