Band 14: Apinis, A.E. (1969): Biocoenotic relationships of grassland soil fungi S. 68 - 85

Biocoenotic relationships of grassland soil fungi

In grassland soils various ecological groups of fungi produce distinct mycocoenoses depending upon the type of vegetation, climate, and factors of the soil environment. Above all, the presence of these heterotrophic organisms depend upon a continuous supply of organic energy sources (substrata) which are produced by the roots of the respective vegetation. Consequently, the quantity and quality of a soil fungal population primarily depends upon the distribution and productivity of the root mass in soil. In areas with an oceanic climate (Western Europe) the root production in a permanent grassland may reach 6.000 kg/ha but in semi-arid countries of Eastern Europe grass root yields are reported even as high as 20.000 to 25.000 kg/ha annually. In a balanced environment the amount of organic matter produced annually is more or less the same as the annual rate of decomposition by soil microorganisms including the fungi and the soil fauna. The ecological factors of soil environment, such as soil aeration, are important too in this complex interdependence, as it is clearly shown by the data of root mass distribution and the activity of the respective soil mycoflora (cf. Fig. 1 & Table 1) in the permanent alluvial pasture soils near Nottingham, England. Various fungi of these grassland soils possess a wide ecological diversity in decomposition of organic matter and display favourable (symbiosis) or unfavourable (parasitism) relationships within the grassland biocoenose but also may influence in one or another way higher plants and other soil organisms by their biosynthetic activity. According to observations made, the rhizosphere and the root surface mycoflora of the grassland vegetation appears just as an initial phase of root colonization by fungi which increase upon the ageing roots thus initiating biological crumb formation in the turf layer of the top soil. The formation of this highly desirable crumb structure is a complex and dynamic process involving the root systems of various plants and the soil microorganisms in which the population of soil fungi play a distinct part indicating the outset, optimum and the decline of crumb formation and desintegration in a particular microniche of the soil.

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