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dc.contributor.advisor Ammer, Christian Prof. Dr.
dc.contributor.author Ehbrecht, Martin Alexander
dc.date.accessioned 2018-02-01T10:12:59Z
dc.date.available 2018-02-01T10:12:59Z
dc.date.issued 2018-02-01
dc.identifier.uri http://hdl.handle.net/11858/00-1735-0000-002E-E341-A
dc.language.iso eng de
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subject.ddc 570 de
dc.title Quantifying three-dimensional stand structure and its relationship with forest management and microclimate in temperate forest ecosystems de
dc.type cumulativeThesis de
dc.contributor.referee Ammer, Christian Prof. Dr.
dc.date.examination 2017-12-11
dc.description.abstracteng Summary Forest management modifies the spatial structure of forest ecosystems, which is considered to be relevant for habitat availability and biodiversity as well as several ecosystem processes and functions. Contrary to tree-attribute based measures of stand structure, laser scanning-based approaches allow to quantify the structure of forest ecosystems holistically with high detail and accuracy. In order to investigate impacts of forest management on three-dimensional stand structure and its relationship with forest microclimate, metrics and indices were developed within the frame of this work that quantify stand structure based on 3D point clouds obtained from terrestrial laser scanning. First, the effective number of layers (ENL) was introduced as a measure to describe the vertical structure of forest stands (chapter 2). By applying diversity indices to the vertical distribution of foliage and woody components, different stand types could be differentiated based on their vertical structure and its horizontal variability. ENL values increased with increasing stand height and a more even filling of vertical layers with foliage and woody components. Subsequently, a stand structural complexity index was developed, which is based on the fractal dimension of cross-sectional polygons through a forest stand, which were derived from single terrestrial laser scans (chapter 3). As the fractal dimension itself is a scale-independent measure to quantify object complexity, ENL was used to scale index values by taking vertical structure into account. The resulting stand structural complexity index (SSCI) intended to quantify the complexity of three-dimensional stand structure holistically, without taking individual tree attributes into account. SSCI values increased from low to high tree size variability, tree size differentiation and decreased with increasing regularity of tree spacing patterns. Moreover, the newly developed index was able to differentiate differently managed stands with different main tree species and was correlated with microclimatic variables. Based on these findings and the hypotheses that several ecosystem processes and functions are affected by microclimatic conditions, the stand structural drivers of the diurnal temperature range (microclimatic indicator) were investigated in chapter 4. In this context, it was shown that canopy openness and a multi-layered vertical structure are the main structural drivers of the diurnal temperature range in temperate forests. The diurnal temperature range decreased with decreasing canopy openness and increasing vertical differentiation. Ultimately, SSCI was then used to investigate impacts of forest management on stand structural complexity in temperate forest ecosystems (chapter 5). Based on subsets of 150, 1 hectare sized experimental forest research plots, representing major stand types in Central Europe, it was shown that even-aged forest management negatively impacts stand structural complexity on stand level compared to uneven-aged forest management and unmanaged forest, whereas it creates a wide variety of structural conditions on landscape scale. Moreover, tree species composition and mixing affect stand structural complexity, whereby broadleaved stands with European beech (Fagus sylvatica) as main trees are characterized by a significantly higher structural complexity than coniferous stands with Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). In this context, an increasing basal area share of coniferous trees resulted in decreasing stand structural complexity. Knowing the direct structural drivers of forest microclimate from chapter 4, indirect effects of forest management on the diurnal temperate range were additionally investigated and compared between even-aged, uneven-aged and unmanaged forests. It was shown that effects of forest management on microclimatic conditions are more pronounced in even-aged forest management systems than in uneven-aged systems and unmanaged forests, mainly due to the removal of shelterwood at the end of a management cycle. The metrics and indices introduced in this study showed a high explanatory power in order to reveal relationships between forest management, stand structure and microclimate. Beyond the use as explanatory variables for research purposes, they might be further considered to be used to monitor long-term forest development, since terrestrial laser scanning proved to be an efficient and rapid method for data acquisition. de
dc.contributor.coReferee Hölscher, Dirk Prof. Dr.
dc.subject.eng Three-dimensional stand structure de
dc.subject.eng Forest management de
dc.subject.eng Silviculture de
dc.subject.eng Terrestrial laser scanning de
dc.subject.eng Microclimate de
dc.identifier.urn urn:nbn:de:gbv:7-11858/00-1735-0000-002E-E341-A-0
dc.affiliation.institute Fakultät für Forstwissenschaften und Waldökologie de
dc.subject.gokfull Forstwirtschaft (PPN621305413) de
dc.identifier.ppn 1012202380

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