Soil variability in naturally disturbed Norway spruce forests in the Carpathians: Bridging spatial scales

Abstract

We studied soils at three sites of natural mountain spruce (Picea abies (L.) Karst.) forests on metamorphic, volcanic and sedimentary bedrock. A total number of 1107 soil profiles were described within the continuous areas ≥ 40ha. Geostatistical techniques were used to describe the spatial pattern and to detect the scale (range) and the degree of spatial dependence in soil data from 1 to 300m distance in order to answer the following questions: Are there some general patterns of soil variability in natural mountain spruce forests? How does soil variability develop through spatial scales on different geological bedrock? How do soil spatial patterns reflect the structure and disturbance history of forest stand?At the sites on metamorphic and volcanic bedrock, thicknesses of organic and A horizons showed mostly fine-scale patterns with autocorrelation rages 2–17m. Entic Podzols, the prevailing soil taxonomic unit within both the sites, indicated spatial patterns with autocorrelation ranges 32 and 27m, whereas characteristics related to vertical eluviation (Albic Podzols and Ae occurrence, E- and Bhs-horizon thickness) showed autocorrelation ranges 24–31m and 19–22m, respectively. In contrast, on sedimentary bedrock soil characteristics showed mostly autocorrelation through the scales or a nested spatial structure. The dominant Leptosols typically occurred side by side with deeply developed soils as Albic Podzols at distances from 9 to 10m, or in large continuous areas without fine earth with a range of 124m. On metamorphic bedrock, where the forest stand developed under predominantly low-severity disturbances, organic horizon forms showed typically short autocorrelation ranges 4–11m, in contrast to the mostly longer ranges 30–59m on volcanic bedrock, where the stand originated mostly from large-scale highly severe disturbances. Distinct periodic patterns in the uppermost organic horizons with wavelengths 5–7.7m were observed at the site on volcanic and sedimentary bedrock, probably reflecting the influence of non-suppressed canopy trees with a tendency toward regular spacing.