Articles by Christopher Morhart

Growing Prunus avium L. within an agroforestry system (AFS) may result in sun damage to cambial tissues on sun-exposed bole faces. There are two periods of risk of damage caused by insolation to exposed tree boles, the summer, when cambial temperatures become too high, or during winter, when the frozen dormant cambium tissue thaws and then rapidly re-freezes, a phenomenon commonly referred to as sunscald or southwest disease. Damage on the south western bole face was observed on a number of P. avium within an AFS. Five trees were sampled to assess the period in time that damage occurred. To retrospectively investigate such damage, bark surface temperature data were collected over a two year period for a further five P. avium and analysed. It was shown that bark surface temperature on the south western bole face reached nearly 50 °C during summer and experienced a maximum range of 38 °C within a 24 hour period in spring. A specially formulated white paint was applied to two trees, thus, testing a method to reduce the risk of sun damage. Two models were constructed to predict maximum and minimum daily bark surface temperature using maximum, minimum and mean daily air temperature, daily sum of sunshine hours, cloud cover, wind speed, relative humidity, maximum solar elevation and height on the tree bole as predictor variables. The damage occurred during winter 2009/2010. The models were used to identify maximum and minimum bark surface temperatures during that winter enabling the identification of possible damage events.

• Sheppard, Chair of Forest Growth and Dendroecology, Albert-Ludwigs-University Freiburg, Tennenbacher Straße 4, 79106 Freiburg, Germany http://orcid.org/0000-0002-4959-7069 E-mail: jonathan.sheppard@iww.uni-freiburg.de
• Morhart, Chair of Forest Growth and Dendroecology, Albert-Ludwigs-University Freiburg, Tennenbacher Straße 4, 79106 Freiburg, Germany http://orcid.org/0000-0003-1874-5011 E-mail: christopher.morhart@iww.uni-freiburg.de
• Spiecker, Chair of Forest Growth and Dendroecology, Albert-Ludwigs-University Freiburg, Tennenbacher Straße 4, 79106 Freiburg, Germany E-mail: instww@uni-freiburg.de

• Kretschmer, Chair of Forest Growth, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: ursula.kretschmer@iww.uni-freiburg.de
• Kirchner, VOLKE Consulting Engineers GmbH, Schätzweg 7-9, 80935 München, Germany E-mail: nadeschda.kirchner@volke.muc.de
• Morhart, Chair of Forest Growth, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: christopher.morhart@iww.uni-freiburg.de
• Spiecker, Chair of Forest Growth, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: instww@uni-freiburg.de

In this paper, we present a new methodology that directly extracts the geometry of woody features (wood and bark) and foliage from 3D data originating from terrestrial laser scans. Our goal was to enhance the precision of radiative transfer models for modelling tree shading by using highly resolved 3D tree models. The approach was tested on a single apple tree (Malus domestica (Suckow) Borkh.) in a peri-urban setting and was validated by utilising an open-source radiative transfer model and comparing the simulation output with in-situ measurements of photosynthetically active radiation (PAR) as well as simulations utilizing turbid voxels of 0.2 m and 1 m edge length. The in-situ measurements of 60 PAR sensors showed a correlation coefficient (r) of 0.92 with the simulated light intensities for the reconstructed polygons which was higher than for the voxel-based approaches (0.2 m:  r = 0.85, 1 m: r = 0.73). We were able to demonstrate that our approach effectively simulates light extinction through the canopy. This innovative method has the potential to easily provide detailed insights into high resolution radiation patterns within forests, which are connected to multiple ecosystem functions like species and habitat diversity.

• Frey, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0001-7895-702X E-mail: julian.frey@wwd.uni-freiburg.de
• Schindler, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0003-2972-1920 E-mail: zoe.schindler@wwd.uni-freiburg.de
• McClatchy, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: patrickjmcclatchy@gmail.com
• Morhart, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0003-1874-5011 E-mail: christopher.morhart@wwd.uni-freiburg.de
• Larysch, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0002-1191-5770 E-mail: elena.larysch@wwd.uni-freiburg.de
• Seifert, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany; Department of Forest and Wood Science, Stellenbosch University, Private Bag X1, Matieland, 7602, Stellenbosch, South Africa https://orcid.org/0000-0002-9611-6272 E-mail: thomas.seifert@wwd.uni-freiburg.de