Influence of selected forest tree species on soil properties in mixed mountain forests in the Alps

Drevesne vrste vplivajo na tla z vnosom nadzemnega in podzemnega opada, absorpcijo hranil in vode iz različnih plasti tal ter s sodelovanjem z različnimi talnimi organizmi. V magistrski nalogi smo preučevali vpliv dveh drevesnih vrst na kemijske lastnosti tal, mikrobno biomaso in sestavo talnih mikrobnih združb. Tla smo vzorčili v bukovem (Fagus sylvatica L.) in smrekovem (Picea abies (L.) Karsten) sestoju z isto združbo tal na isti matični podlagi. Na lokaciji bukovega sestoja je bil pred 20-30 leti mešani sestoj jelke, smreke in bukve, v katerem je jelka prevladovala. Vsebnost skupnega organskega C (Corg), skupnega N, topnega Corg in topnega N je bila v zgornjih 10 cm tal značilno večja v smrekovem kot v bukovem sestoju (11,54 vs. 9,00 %0,63 vs. 0,52 %15,30 vs. 9,45 mg C kg-1 suhih tal2,90 vs. 1,65 mg N kg-1 suhih talzaporedoma). V bukovem sestoju pa je bila, v primerjavi s smrekovim, na tej globini večja nasičenost z izmenljivimi bazičnimi kationi (84,60 vs. 43,60 %), predvsem Ca. Značilnih razlik v pH tal med sestojema nismo zaznali, kar kaže na veliko puferno sposobnost tal in s tem počasen odziv pH na spremembe v sestavi sestoja. Mikrobni biomasni ogljik, določen z metodo fumigacije s kloroformom, je bil v zgornji globini značilno večji v smrekovem v primerjavi z bukovim sestojem (584,66 vs. 491,98 mg C kg-1 suhih tal). To pa ne velja za mikrobni biomasni dušik in mikrobno biomaso ocenjeno s količino skupne DNK, kjer nismo zaznali značilnih razlik. Številčnost mikrobne združbe bakterij, gliv in krenarhej smo določili s kvantitativno verižno reakcijo s polimerazo (qPCR). Značilnih razlik med sestojema v številčnosti bakterij in gliv ni bilo. Značilno večja številčnost je bila pri krenarhejah v smrekovem sestoju v spodnji globini, v zgornji pa je bila ta mejna (p = 0,053). Rezultati te študije so pokazali vpliv drevesnih vrst na izbrane lastnosti tal, vendar bi bilo, upoštevajoč, da sestoja nista bila povsem primerljiva, smiselno preveriti tudi vpliv starosti sestoja in primerljivost ostalih okoljskih razmer. Potrebne so nadaljnje bolj poglobljene študije sestave mikrobnih združb, npr. mikoriznih gliv.Tree species influence the soil by adding above- and below-ground litter, absorbing nutrients and water from different soil layers, and interacting with different soil organisms. In this master thesis, the influence of two tree species on soil chemistry, microbial biomass, and community composition was investigated. Soil was sampled down to parent material in beech (Fagus sylvatica L.) and spruce (Picea abies (L.) Karsten) stand with the same soil group on the same parent material. In the place of the beech stand, there was a mixed stand of fir, spruce and beech 20-30 years ago, dominated by fir. The contents of total organic C (Corg), total N, soluble Corg, and soluble N in the top 10 cm of soil were significantly higher in the spruce than in the beech stand (11.54 vs. 9.00 %0.63 vs. 0.52 %15.30 vs. 9.45 mg C kg-1 dry soil2.90 vs. 1.65 mg N kg-1 dry soilrespectively). Beech stand was found to have a higher base saturation compared to the spruce stand at this depth (84.60 vs. 43.60 %), mainly Ca. No significant differences in soil pH were observed, indicating a high buffering capacity of the soil and thus a slow response of pH to changes in stand composition. Microbial biomass C, determined by the chloroform fumigation method, was significantly higher in the spruce stand compared to the beech stand in the upper depth (584.66 vs. 491.98 mg C kg-1 dry soil). This is not the case for microbial biomass N and microbial biomass estimated by the total DNA, for which we found no significant differences. The abundance of the total microbial community, bacteria, fungi and Crenarchaea, was determined by quantitative polymerase chain reaction (qPCR). There were no significant differences in the abundance of bacteria and fungi. Significantly higher abundance was observed for Crenarchaea in the spruce stand at the lower depth, while it was marginal at the upper depth (p = 0.053). The results of this study showed the influence of tree species on selected soil properties, but given that the two stands were not entirely comparable, it would be worthwhile to also check the influence of stand age and the comparability of other environmental conditions. Further, more in-depth studies on the composition of microbial communities, e. g. mycorrhizal fungi, are needed