Analysis of OF-layer humus mass variation in a mixed stand of European beech and Norway spruce: An application of structural equation modelling

Latent structures are of great importance in order to understand and analyse processes determining humus mass variation. In our model, “latent variables” are identified, which explain the contribution of measured variables to improvement or deterioration of humus decomposition, and hence more or less accumulation of organic material in the surface humus layers, in our case the OF layer. Spruce needle input impedes humus dynamics, while beech leaf litter input and higher throughfall amounts show supporting effects. These model results are in agreement with formerly reported findings, but yield further an interval-scaled combined measure which is better founded and more comprehensive than earlier descriptive approaches to the single ecological factors involved. Besides of the ecological interpretation of the results we succeed in determining a valid structural equation model taking into account all relevant ecological factors of humus decomposition.