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Gewählte Master / Diploma Thesis:

Mani Prasad Nirola (2016): Drivers of soil respiration in two mountain forests in Bhutan.
Master / Diploma Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 94. UB BOKU obvsg

Data Source: ZID Abstracts
Soil respiration (Rs) was measured in two mountain forests in Bhutan viz; a cool temperate conifer forest (CF) and a warm temperate broadleaved forest (BF) from July to September 2015. Variations in Rs between the zone close to the stem and inter-stem space were studied. In addition we measured whether Rs differed between different tree species. In laboratory incubations, the dependence of Rs on soil water content and soil temperature were examined. Basal respiration (R10) and temperature sensitivity (Q10) of Rs were calculated. The knowledge on the persistence of soil carbon and temperature sensitivity of soil respiration has been considered to be of paramount importance. Soil respiration and the temperature sensitivity of soil respiration are two important parameters that have been commonly used in predicting the response to global warming. CF and BF represent dominant forest types in Bhutan and the eastern Himalayas. Rs increased by ~ 30% from the canopy gap centre to the tree stem zone but tree species did not significantly affect Rs rates. Soil temperature and Rs showed a strong positive relationship (R2 > 0.90). Soil moisture and Rs showed a unimodal relationship, where Rs was low at a lower soil moisture, increased to maximum at intermediate moisture and decreased at higher moisture content (R2 > 0.92). The Q10 and R10 values ranged from 1.78 to 2.60 and 0.35 to 3.05 µmol CO2 m-2 s-1, respectively (n = 6). The temperature sensitivity of mineral soil CO2 efflux at the lower elevation broadleaved forest (BF, Q10 = 2.40) was similar to the temperature sensitivity of the higher elevation conifer forest (CF, Q10 = 2.35). The difference in temperature sensitivity was even less pronounced in forest floor material (BF, Q10 = 2.28, CF, Q10 = 1.98). The temperature sensitivity of Rs increased at lower temperatures and was significantly lower in dry soil (BF, Q10 = 1.58, CF, Q10 = 1.61, p < 0.05). Therefore, changes in soil temperature and precipitation are expected to affect soil mineralization and subsequently the soil CO2 efflux and carbon dynamics of the two forest ecosystems studies. Key words: Soil respiration, Himalaya, Tree species, Spatial heterogeneity, Temperature-dependence, Moisture-dependence, Incubation, Q10, R10


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