Influence of slope aspects on soil chemical and biochemical properties in a Pinus laricio forest ecosystem of Aspromonte (Southern Italy)

The study assesses the influence of soil aspect on differences in soil chemical and biochemical properties. We examined soils on contiguous south- and north-facing slopes of the Aspromonte Mountains (Calabria, Southern Italy), influenced by the same climate, vegetation and parent material. In each of the two topographic aspects, six study sites were described. The investigated variables were air temperature, soil temperature, soil water content, photosynthetically active radiation, soil microbial biomass C, organic matter content, total nitrogen, total water-soluble phenols, humic and fulvic acids. Fluorescein diacetate hydrolytic activity, dehydrogenase, protease urease, alkaline and acid phosphatases, enzymes related to soil microbiological activity and hydrolysing coefficient, an empiric indicator of soil quality, were analyzed and interpreted. Except in few cases, all considered soil properties and microclimate variables showed significant differences between topographic aspects. In the soil on the north-facing slope, a lower content of organic matter and microorganisms and a lower activity of the enzymes related to soil microbiological activity were observed. The differences may be attributed to topographic aspect-induced microclimatic differences, which causing differences in the biotic soil component and organic matter trend, affect soil fertility.