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Gewählte Master / Diploma Thesis:

Sarah Oberdorfer (2016): Changes in physicochemical and microbial soil parameters during secondary forest succession in southwest Costa Rica.
Master / Diploma Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 74. UB BOKU obvsg

Data Source: ZID Abstracts
Due to constantly increasing deforestation in the tropics, secondary forests are steadily gaining in importance and currently constitute approximately half of the global tropical forest area. As vegetation dynamics are strongly interrelated with soil processes we expected changes in soil after pasture abandonment and with secondary forest succession. We compared physicochemical soil parameters by using a chronosequence approach with age groups for 2 pastures (PA), 2 primary forests (PF > 100 years) and 12 secondary forests grouped by age (SF1 5.5–13 years, SF2 14–27.5 years, SF3 28–55 years). Soil samples were taken to 45 cm and divided in topsoil (0–15 cm) and subsoil (15–45 cm). All investigated soils were acidic with lowest pH values in young SF sites, which was accompanied by low base saturation. This possibly reflects high nutrient uptake in the early stage of succession due to fast above ground biomass (AGB) accumulation. Soils were high in soil organic C (SOC), total N, microbial biomass C and N, but had low levels of Olsen P and microbial biomass P. Bulk density was generally low, but higher on PA than SF sites while soil aggregate stability was high and remained unchanged during land-use transition. Furthermore, no significant changes were observed for SOC and N stocks across the chronosequence but all investigated soils stored substantial amounts of SOC. Total ecosystem C stocks increased from PA to SF sites indicating a high storage capacity of AGB with progressing secondary succession. Based on δ13C values we detected highest losses in pasture-derived C (C4-C) in the early stage of succession; however, SOC carbon turnover was slow. The present study emphasizes the high importance of secondary forests for carbon sequestration in the tropics.

Beurteilende(r): Zehetner Franz

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