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Dissertation
Geospatial crop yield modeling for climate change risk transfer, impact assessment, and adaptation strategies
(2023)
Changing climate and weather patterns increase the pressure on food production systems worldwide, significantly impacting livelihoods and economies at various scales. Understanding and adapting/mitigating climate change are essential to cope with the adverse effects of climate change. Biophysical crop modeling offers a unique way to assess the pros and cons of different adaptation strategies because they integrate physical and biological principles to simulate the use and allocation of captured resources mechanistically. ...
Dissertation
Using Optical Satellite Imagery to Monitor and Understand Agricultural Land-cover Change
(2020-06)
The activities of humans have transformed the earth over the last decades. The transformation is estimated to increase further in response to the growing world population. This has caused many countries to devise means to utilize resources sustainably. Bio-economy is seen as a means to reduce the high reliance on fossil materials and ensure the provision of raw materials, energy and food to the increasing world population in a sustainable manner. However, the rising demands for biomass to produce bioenergy have relied ...
Dissertation
Robustness of portable and laboratory-based visible/near- and mid-infrared spectroscopy for optimized determination of temporally and spatially variable soil properties
(2021)
Application of visible/near- (VISNIRS) and mid-infrared (MIRS) spectroscopy to the field of soil science is promising, as it allows information about a range of properties to be collected simultaneously and rapidly, thereby providing high spatial and temporal resolution data for use in, e.g., soil mapping, precision agriculture, and long-term monitoring. However, investigation of the conditions under which visNIRS and MIRS can replace traditional lab methods is required, as the accuracy, robustness, and efficiency ...
Dissertation
Effects of climate change on fungal community structure and organic matter turnover in soil profiles along elevation gradients in alpine ecosystems
(2019-10)
Although elevation patterns of diversity for plants and animals are well known, understanding of variations in fungal community structure along elevation gradients is limited. Soil fungi play an important role in soil microbial communities, where they improve soil organic matter (SOM) turnover and nutrient circulation. Hence, any change in fungal community structure will have strong effects on soil and ecosystem functioning. The main purpose of this thesis is therefore to investigate how climate induced shifts in ...
Dissertation
Fine-scale grassland monitoring using unmanned aerial vehicle borne remote sensing
(2020-04)
RS is widely employed as a non-destructive methodology to monitor grasslands. Usage of UAV as the RS platform benefits to provide high spatial (fine-grain) and temporal resolution, unclouded data over small grassland extent. Therefore, this thesis evaluated the applications of UAV-borne RS for fine-scale grassland monitoring along with practical farm condition. Grass biomass estimation, predicting forage quality of grass and mapping invasive lupine in grasslands are considered as applications of UAVborne RS.
Dissertation
Factors and mechanisms controlling soil organic carbon turnover in subsoils of agricultural sites
(2016-07-12)
Two-third of the terrestrial C is stored in soils, and more than 50% of soil organic C (SOC) is stored in subsoils from 30 – 100 cm. Hence, subsoil is important as a source or sink for CO2 in the global carbon cycle. Especially the stable organic carbon (OC) is stored in subsoil, as several studies have shown that subsoil OC is of a higher average age than topsoil OC. However, there is still a lack of knowledge regarding the mechanisms of C sequestration and C turnover in subsoil.
Three main factors are discussed, ...
Dissertation
Effects of tillage on processes of organic matter sequestration
(2010-06-28)
To increase the organic matter (OM) content in the soil is one main goal in arable soil management. The adoption of tillage systems with reduced tillage depth and/or frequency (reduced tillage) or of no-tillage was found to increase the concentration of soil OM compared to conventional tillage (CT; ploughing to 20-30 cm). However, the underlying processes are not yet clear and are discussed contradictorily. So far, few investigations were conducted on tillage systems with a shallow tillage depth (minimum tillage = ...
Dissertation
Effects of the application of biochar and organic fertilizers as well as temperature on soil carbon and aggregate dynamics
(2017-11-27)
Soil aggregate formation is an important process for long-term carbon storage in soils. While it has been shown that plant residues exert a positive influence on aggregate formation, the effects of organic fertilizers such as cattle slurry or manure as well as the effects of biochar application to soil are less clear. Furthermore, little is known about the role of increased soil temperatures in aggregate dynamics.
The main objectives of this thesis were to analyse the effects of (i) cattle slurry and manure, (ii) ...
Dissertation
Amount, composition and turnover of organic matter in topsoils and subsoils under mature beech forest
(2017-12-15)
Two-third of the terrestrial carbon (C) is stored in soils, and up to 63 % of the soil organic C (SOC) is stored in subsoils (i.e. below 30 cm soil depth). Forest soils account for nearly 70 % of the global SOC, demonstrating their great importance regarding the global carbon cycle. The higher average age of the OC stored in subsoil indicates that the subsoil OC is more stable against microbial decomposition. The capability of soil to stabilize OC is affected by substrate characteristics (e.g. size, distribution, ...