From Points to Forests - The potential of 3D point clouds to evaluate the structural complexity of differently managed beech forests
von Liane Carolin Neudam
Datum der mündl. Prüfung:2024-02-09
Erschienen:2024-03-04
Betreuer:Prof. Dr. Christian Ammer
Gutachter:Prof. Dr. Christian Ammer
Gutachter:Prof. Dr. Dominik Seidel
Gutachter:Prof. Dr. Andreas Schuldt
Gutachter:Prof. Dr. Peter Annighöfer
Dateien
Name:Neudam_2024_eDiss.pdf
Size:4.07Mb
Format:PDF
Zusammenfassung
Englisch
Climate change is leading to global shifts that can create a particular challenge for the stability and vitality of forest ecosystems. In the temperate forests of Central Europe, the natural forest vegetation is dominated by European beech. Although beech is competitive and has a large site amplitude, it is unclear whether it can adapt to the consequences of climate change. Forestry science is confronted with the task of dealing with the challenges of climate change and preserving the forest ecosystem and its functions. The stability of a forest is closely linked to its structural complexity, which can be controlled by silvicultural measures. Quantifying the structural complexity of forests and their changes is the fundamental element for objectively evaluating forests or their management concepts. The aim of this dissertation is to contribute to this subject. The research is based on 3D point clouds from laser scans of beech forests in Germany with different management histories, whose structural complexity is quantified and compared using fractal analysis. In a first study, the accuracy of the scanning approach for monitoring seasonal changes in structural complexity is investigated (chapter 2). Repeated measurements with the mobile laser scanner (MLS) show that the effects of foliage (leaves emergence vs. leaves dropping) and management (managed vs. formerly managed) on the structural complexity of the forest are quantifiable and can thus be monitored with the applied method. Our second and central study focuses on the simulation of different silvicultural treatments on 3D point clouds of real forest stands. A special feature here is that each treatment type is simulated on each study stand so that only the treatments can be compared. The effect of the treatments on the change in structural complexity and on short-term economic gain is then investigated (chapter 3). Six different treatments are simulated in 19 different real beech forest stands, and each treatment has a different negative effect on the structural complexity of the stands right after harvesting. We found that no trade-off between the objectives of small structural changes in the stand and a high economic return is necessary. The aim of the third study presented here is to evaluate the closeness to nature of the study stands by comparing them with primary forests as a natural reference (chapter 4). To this end, the scan data from beech forests with different management histories were compared with data from primary forests in terms of their structural complexity and stem form. Our results show that although near-natural managed beech forests do not have the same stem forms as primary forests, they can achieve the same structural complexity of the stands. The methodology of laser scanning technology is characterized by high accuracy and is suitable as a tool to capture the smallest changes in the structural complexity of forests. Different management methods can be objectively evaluated and compared in terms of their structural complexity on the basis of laser scanning data. The present results show that laser scanning can also help in the selection of future management methods in order to investigate their effects on the structural complexity of a stand before implementation in practice. Thus, the presented methodology provides a detailed and efficient assessment of the structural complexity to evaluate the forest condition and possible management methods. It could provide an important instrument for the target-oriented development of climate-adapted forests.
Keywords: Forests; Beech forests; Laserscanning; Structural complexity; Silviculture; Close to nature management; Fagus sylvatica