The focus of this thesis is on the dynamics and functions of saprotrophic soil fungi during conversion from an arable land into a natural ecosystem (heathland) and to asses their effects on soil... Show moreThe focus of this thesis is on the dynamics and functions of saprotrophic soil fungi during conversion from an arable land into a natural ecosystem (heathland) and to asses their effects on soil ecosystem processes. Chapter 2 describes that fungal biomass in abandoned arable land is not increasing for at least 3 decades to the level of a natural ecosystem. Opportunistic fungi showed to be responsible for the decomposition processes, and these fungi are stimulated by large sizes of nitrogen-rich substrate buried in soil (Chapter 4& 5). Chapter 3 presents that no large amounts of phosphorus seem to leach into deeper soil layers after land abandonment. In Chapter 6 it is shown that the establishment of Calluna vulgaris in a recently abandoned arable land can be due to a fast colonization of Calluna immediately after abandonment and the reduction of microbial nitrogen mineralization, in combination with the colonization of Calluna roots by ericoid mycorrhizal fungi. In Chapter 7 it is concluded that an increase in fungal biomass in ex-arable soils can be of interest for soil ecosystem restoration and this may be triggered by the introduction of large particles of recalcitrant organic matter together with sufficient fungal biomass. Show less
