Soil chemical and biological changes through the N2 fixation of black locust (Robinia pseudoacacia L.) - A contribution to the research of tree neophytes : Dissertation Georg-August-Universität, Göttingen, Fakultät für Forstwissenschaften und Waldökologie
Worldwide the land area covered by stands with the neophytic tree legume Robinia pseudoacacia L. (black locust) has expanded to about 3 Mio. ha and is predicted to extend further in the future. Besides the rising atmospheric inorganic N deposition (mean 20-30 kg N ha-1 yr-1) to forest ecosystems in Europe, N2 fixation rates (35-150 kg N ha-1 yr-1) in black locust stands can enhance the problems associated with increasing N inputs into forest ecosystems. The strong N-enrichment in the vegetation and soils and the subsequent processes of N transformation under forest stands of Robinia can result in high nitrification rates in the mineral soil. Moreover, leaching of nitrate and base cations may occur, causing a significant drop in the pH of the surface soil that can lead to nutrient depletion as well as to nitrate contamination of the groundwater. After long-term cultivation of Robinia stands on the same site decreases of their yield performance are observed. However, the involved processes responsible for this phenomenon are currently unknown. The present work contributes to the discussion of the implementation of the neophytic tree Robinia pseudoacacia L. according to its impact on chemical and biological soil parameters. Additionally, the aim of the study was to clarify the processes responsible for the observed growth decline after repeated black locust cultivation on the same site.
