A spatial approach to soil‐ecological experimentation at landscape scale

Abstract

AbstractThe upscaling of soil‐ecological processes to larger landscape units represents a special challenge to soil ecology. Results from micro‐ or mesocosms cannot easily be transferred to other scales because effects are often scale‐dependent. In this context, field experiments which take into account the heterogeneity of the landscape may be promising. Therefore, we carried out an experiment based on a transect study in the agrolandscape of NE Germany on heterogeneous sandy soil in which the feeding activity of the soil‐organism community was assessed by means of the bait‐lamina test at each of the 101 transect locations. At every 4th position, prior to the measurement the soil biota were stimulated by a treatment consisting of adding easily available C and water to the soil. Our aim was to test whether this kind of spatial approach enables to separate effects induced by treatments from landscape effects. The results showed a highly variable feeding activity along the transect after 4 weeks. Despite this variability, a basic trend could be identified which was related to a landscape factor, i.e., the relief. On upper‐slope positions, the feeding activity tended to be less in comparison to positions down‐slope. At every 4th position of the transect, the stimulating effect of the substrate and water addition could be clearly detected and quantified with spectral and cross‐spectral analysis. It is concluded that effects of treatments in heterogeneous landscapes may be distinguished from site effects when the signal‐to‐noise ratio is high and soil and treatment effects on the variable of interest are sufficiently different from one another. In a heterogeneous landscape with gradients of site properties, a treatment based on the frequency domain and applied in regular intervals can be distinguished with spectral analysis techniques.