Relief-induced feedback mechanisms controlling local podzolization occurrence on flysch slopes – Examples from Outer Western Carpathians (southern Poland)

Abstract

Podzolization is one soil-forming process that at a landscape scale is sensitive to relief-related factors. In the areas where leached and coarse-textured parent material together with humid climate and forest or heath vegetation favour development of Podzols the intensity and advancement of this process are connected with landscape position, inclination, topography and related water table effects. Flysch bedrock, which affects the slope deposits in many mountain regions due to high content of clay, Fe and alkaline compounds in its major part is considered to be a parent material unfavourable for podzolization. On the other hand, podzolization occur locally in soils developed from flysch. The main objective of this study was to determine the role of relief in conditioning podzolization occurrence on flysch slopes in the Outer Western Carpathians in southern Poland. Soils located in two slope transects were studied in terms of weathering rates, aeolian silt admixture, soil properties and soil-forming processes differentiation. Furthermore, at selected sites in situ soil moisture was measured, while the slopes with transects were subject to geomorphometric analysis. Podzols development was evidenced at the uppermost slopes and – locally – at middle slopes. Two feedback mechanisms controlling podzolization occurrence in a small scale were proposed. The first positive feedback loop explained crossing the pedogenic threshold of podzolization via relatively higher soil moisture that lead to slower organic matter turnover and more advanced weathering. This mechanism, in turn, triggered podzolization. The second negative feedback mechanism was responsible for suppression of Podzols development at steep slopes. On the one hand, it was related with active geomorphic processes that caused soil rejuvenation, and with relatively lower soil moisture conditioned by less effective precipitation per unit area on the other. Both resulted in inhibited weathering and precluded podzolization occurrence.