Holzanatomische Analyse diagnostischer Merkmale einer Freilegungsreaktion in Jahrringen von Koniferenwurzeln zur Rekonstrution geomorphologischer Prozesse

Die vorliegende Arbeit befasst sich mit der holzanatomischen Analyse freigelegter Koniferenwurzeln zur Bestimmung spezifischer Freilegungsreaktionen. Die durchgeführte Bestimmung diagnostischer Merkmale in der Zellstruktur erlaubt die genaue Datierung des Freilegungszeitpunktes einer Wurzel. In Kombination mit detaillierten geomorphologischen Kartierungen erlaubt diese neue Methode einerseits die Rekonstruktion erosiver geomorphologischer Prozesse (z.B. Murgänge) wie auch die Bestimmung lokaler Abtragsraten in Gebieten, aus denen bisher keine Messungen vorliegen. Mit dieser Arbeit wurde eine Basis geschaffen, die eine umfassende Einbeziehung der Wurzelanalyse in dendrogeomorphologische Fragestellungen erlaubt

A tool to model 3D coarse-root development with annual resolution

Dynamic root-development models are indispensable for biomechanical and biomass allocation studies, and also play an important role in understanding slope stability. There are few root-development models in the literature, and there is a specific lack of dynamic models. Therefore, the aim of this study is to develop a 3D growth-development model for coarse roots, which is species independent, as long as annual rings are formed. In order to implement this model, the objectives are (I) to interpolate annual growth layers, and (II) to evaluate the interpolations and annual volume computations. The model developed is a combination of 3D laser scans and 2D tree-ring data. A FARO laser ScanArm is used to acquire the coarse-root structure. A MATLAB program then integrates the ring-width measurements into the 3D model. A weighted interpolation algorithm is used to compute cross sections at any point within the model to obtain growth layers. The algorithm considers both the root structure and the ring-width data. The model reconstructed ring profiles with a mean absolute error for mean ring chronologies of <9% and for single radii of <20%. The interpolation accuracy was dependent on the number of input sections and root curvature. Total volume computations deviated by 3.5-6.6% from the reference model. A new robust root-modelling tool was developed which allows for annual volume computations and sophisticated root-development analyse

Incorporating 2D tree-ring data in 3D laser scans of coarse-root systems

In times of global change biomass calculations and the carbon cycle is gaining in importance. Forests act as carbon sinks and hence, play a crucial role in worlds and forests carbon budgets. Unfortunately, growth models and biomass calculations existing so far mainly concentrate on the above-ground part of trees. For this reason, the aim of the present study is to develop an annually resolved 3D growth model for tree roots, which allows for reliable biomass calculations and can later be combined with above-ground models. A FARO scan arm was used to measure the surface of a tree-root segment. In addition, ring-width measurements were performed manually on sampled cross sections using WinDENDRO. The main goal of this study is to model root growth on an annual scale by combining these data sets. In particular, a laser scan arm was tested as a device for the realistic reproduction of tree-root architecture, although the first evaluation has been performed for a root segment rather than for an entire root system. Deviations in volume calculations differed between 5% and 7% from the actual volume and varied depending on the used modeling technique. The model with the smallest deviations represented the structure of the root segment in a realistic way and distances and diameter of cross sections were acceptable approximations of the real values. However, the volume calculations varied depending on object complexity, modeling technique and order of modeling steps. In addition, it was possible to merge tree-ring borders as coordinates into the surface model and receive age information in connection with the spatial allocation. The scan arm was evaluated as an innovative and applicable device with high potential for root modeling. Nevertheless, there are still many problems connected with the scanning technique which have an influence on the accuracy of the model but are expected to improve with technical progres