Search

Interpretation of soil data is necessary to help predict their ecological potentials, limitations, problems, and management needs. We tested the knowledge expressed in taxonomic systems for its ability to be applied in the description and generalization of soil dynamics and behavior. The general hypothesis established for this purpose was ”soil subtypes are proxies for ecological processes”. To facilitate the detection of process intensity and to obtain well-expressed pedogenetic features, we selected a soil catena from an environment known for its severe weathering conditions. The ’Wildmooswald’ catena consists of eight profiles and is situated in the Central Black Forest in South-West Germany. We organized our investigation in the following manner: (i) We ascertained that the catenary soil sequence had a regular pattern. (ii) We confirmed that the soils were connected among each other by a physical link which resulted in lateral subsurface matter translocation. (iii) We investigated the extent to which pedogenetic processes were expressed in terms of taxonomic criteria. (iv) We determined whether a given ecological feature, like trace gas emissions, was reflected in taxonomic categories. We found that the ’Wildmooswald’ soils were linked to each other by a lateral subsurface transport of solutes. We identified redox conditions and an abundance of chelating organic compounds as the main factors in the mobilization/immobilization of elements. Hydrological conditions were the dominant factor of weathering and thus, soil formation, which determined both the intensity of mobilization processes and the intensity of the lateral subsurface transport. Lateral down-slope water movement was identified as the physical link between the soils. Depletion zones were the mid-catena members, where redox conditions led to the removal of manganese and iron. Organic layers, which have accumulated in these soils as a consequence of reducing conditions, acted as sources of dissolved organic carbon. The terminal catena element represents an accumulation zone for Mn, Fe, and dissolved organic carbon. Based on this observation we concluded that, for the greater part of the Wildmooswald soils, taxonomic soil type indeed reflects pedogenetic processes as well as soil matter dynamics. Trace gas time emission patterns, as well as trace gas source strength, which serves as an indicator for short-term ecological dynamics, were found to vary within a soil unit-specific range for either N2O and CH4. We conclude that for the greater part of the ’Wildmooswald’ catena, soil subtypes indeed recognizes and combines pedogenetic processes and soil matter dynamics. The functions and dynamics prevalent at the terminal catena member were not represented adequately by neither the German classification system, World Reference Base nor Soil Taxonomy. This fact should indicate that a review of the classification systems is necessary both generally for their ability to provide functional soil information and specifically for soils showing accumulation of matter at pedon scale.

Während die Schätzung und Bewertung der physikalischen und chemischen Bodeneigenschaften mit Hilfe von bereits bewährten Verfahren durchführbar sind, gibt es für die mikrobiologischen Eigenschaften diesbezüglich noch keinen Schätzrahmen. Das Ziel der vorliegenden Arbeit bestand deshalb in der Entwicklung einer Schätzmethode für den integralen Parameter “mikrobielle Biomasse“. Zu diesem Zweck wurden die Werte des mikrobiellen Kohlenstoffs (Cmik) in 116 Böden natürlicher Gesteine von in- und ausländischen Standorten sowie in 33 deutschen Böden anthropogener Substrate herangezogen. In den betrachteten Böden variierte die Cmik-Menge in den oberen 30 cm zwischen 100 und 4000 kg ha^—1. Dabei wurden für die natürlichen Böden signifikante Beziehungen zwischen dem Cmik einerseits und den Humus- und Tongehalten sowie den pH-Werten andererseits ermittelt. Aus diesen Parametern, die die diagnostischen Merkmale der unterschiedlichen Humusformen darstellen, ließ sich ein einfacher Schätzrahmen für die Cmik-Menge in Ackerböden ableiten. Für die Böden anthropogener Substrate wurde dagegen ein Schätzverfahren entwickelt, in welchem die Substratherkunft und das Entwicklungsstadium dieser Böden mit berücksichtigt werden. Für die Bewertung der geschätzten Menge an mikrobiellem Kohlenstoff sind dabei 6 Cmik-Klassen vorgesehen: < 200 kg ha^—1 (= sehr gering), 200—400 kg ha^—1 (= gering), 400—800 kg ha^—1 (= mäßig), 800—1600 kg ha^—1 (= mittel), 1600—3200 kg ha^—1 (= hoch) und > 3200 kg ha^—1 (= sehr hoch).