University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Doctoral Thesis:
Jasmin Schomakers
(2017):
Carbon dynamics in a disturbed tropical forest ecosystem.
Doctoral Thesis - Institut für Bodenforschung (IBF),
BOKU-Universität für Bodenkultur,
pp 118.
UB BOKU
obvsg
- Abstract:
- The global carbon cycle can be viewed as a series of reservoirs of carbon in the Earth System, which are connected by exchange fluxes of carbon. Tropical forests, including both regrowth and intact forests, constitute the largest component of the terrestrial carbon sink. This sink is vulnerable to climate extremes since disturbance processes readily move carbon stored in aboveground biomass. Globally, climate extremes are increasing. The present work assessed carbon dynamics in a disturbed tropical forest ecosystem with a focus on forest soils. A chronosequence, which substitutes space for time, was established on former landslide scars in the Central Mountain Range of Taiwan, ranging in age from 6 to 41 years. Carbon re-accumulation in biomass and soils was assessed. The aggrading terrestrial ecosystems were strong carbon sinks, and after 41 years of landslide recovery had accumulated about half the carbon of an undisturbed reference site. This work also includes an improved method on assessing soil aggregate breakdown. We applied ultrasonic vibration to disperse the aggregates. The distribution of particles in the soil-water suspension was determined by measuring the X-ray attenuation during sedimentation with a Sedigraph. The study rendered good results at low energy levels (< 10 J cm-3) for macro- and micro-aggregate breakdown for European soils. A third study assessed soil aggregate breakdown along the chronosequence. Two different kinetic energies were calculated to simulate two past typhoon rainfall events, which had a landfall on Taiwan. Sonification experiments revealed the fragile soil structure and that soil aggregates and occluded carbon need several decades to recover from a landslide event and get stabilized to withstand typhoon-induced rainfall. If typhoons increase in magnitude and frequency, soil aggregate breakdown will likely increase and release occluded carbon.
- Betreuer: Zehetner Franz
- 1. Berater: Hein Thomas
- 2. Berater: Mentler Axel