Phytocoenochoras in Arctic tundras: cartographic research method

Abstract

The cartometric and morphometric parameters of phytocoenochoras (heterogeneous territorial units) recognized for the arctic tundra vegetation of the Wrangel Island are studied. The analyses of phytocoenochoras is based on the vegetation map at 1 : 100 000 scale, that was made using ArcGIS 10.1. The cartographical units are the sigma-associations – typological categories of phytocoenochoras of micro- or meso-level (rank). Each sigma-association consists of 2 or more phytocoenoses whose affiliation to a particular vegetation syntaxon was described according to the BraunBlanquet method. Following parameters of contours (polygons) of map are analyzed: area, degree of dissection (tortuosity), granularity (complexity), shape (elongation – roundness), degree of typological contrast, uniformity of differentiation. The first three belong to the category of grafo-analytical parameters; some cartometric indicators are used indirectly for the rest. Average values of parameters are calculated for a number of parameters, but the differences between them are not always proved reliable. Low values characterize three types of parameters, there are: area, degree of partition, fragmentation index. A relatively large value of classification index of differentiation means that some vegetation syntaxa belonging to the different classes or orders may coexist in phytocoenochoras. This makes it possible to use the syntaxa of floristic classification for vegetation mapping at a given map scale not fearing that too broad syntaxa will neutralize all the diversity of the abiotic environment.