L. Hably szerk.: Studia Botanica Hungarica 23. 1992 (Budapest, 1992)
Németh, Ferenc: Vegetation structure studies on steppe and semidesert plant communities of Outer Mongolia 1. Textural relations
STUDIA BOTANICA HUNGARICA (An tea: Fragmenta Botanica) XXIII. 1992 pp. 135-161 Vegetation structure studies on steppe and semidesert plant communities of Outer Mongolia 1. Textural relations By F. NÉMETH (Received December 16,1991) Abstract: Eight linear samplings of 510-1070 microquadrats (0.01 - 0.25 m 2 ) were undertaken in different lowland and high-mountain semidesert and steppe plant communities of Outer Mongolia for a complex textural and structural analysis. In this paper species- and family-level richness, floral composition, life-form spectra are analyzed. INTRODUCTION In order to decipher the basic rules of spatial organization of plant communities, one has to find "clear", undisturbed objects in sufficient extension and quantity for comparative analysis. It is almost impossible to find such localities in Europe, at least in the case of the steppic and semidesert communities which possess the advantage of the relative simplicity too, but Mongolia has proven to be an optimal site. As much as 78% of the country is extensively used pasture and the ratio of the arable land amounts only about 1.0% (National Economy of the MPR - Statistical collection, 1981). The vegetation history of the last glacial and interglacial periods has been relatively uneventful without drastic changes such as e.g. in Europe (SHILOVA 1973). The various types of that semideserts - one feels as if one walks on top of centuries-old, buried but living forests - suggest that the plant species can replace each other in a community based on their ecological role, and the differences between their floral composition are mainly "historical", due to past events, representing some kind of "frozen chance". The physiognomy and patchiness of a Brachanthemum gobicum -semidesert seems very similar to a Reaumuria soongorica- or a Potaninia mongolica- or an Eurotia ceratoides- or a Convolvulus fruticosustype, and also very similar is the climate and the soil of these habitats (taxonomy and biogeographical subdivision after GRUBOV 1982). This phenomenon is contrastive in these poor communities, where the patchiness-creating unit is a population of a species, just like as in the richest ones, in the tropical rain forests, where the compartments of the life forms play the same role (PÓCS 1976). Probably it is valid also for the medium rich communities, but it is more difficult to determine their relevant units, the coalitions. 135
