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Articles by Christopher Morhart

Category : Research article

article id 1313, category Research article
Jonathan Sheppard, Christopher Morhart, Heinrich Spiecker. (2016). Bark surface temperature measurements on the boles of wild cherry (Prunus avium) grown within an agroforestry system. Silva Fennica vol. 50 no. 3 article id 1313. https://doi.org/10.14214/sf.1313
Keywords: valuable timber; sunscald; sunburn; southwest disease; cambium; alley cropping
Highlights: Widely spaced trees within agroforestry systems are at risk of sun induced damages; Bark surface temperature on the south western bole face reached nearly 50 °C in summer and experienced a maximum range of 38 °C within a 24 hour period in spring; Maximum and minimum daily bark surface temperatures are modelled using climatic and solar position data; The application of white paint to stems reduces the bark surface temperature.
Abstract | Full text in HTML | Full text in PDF | Author Info

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 ORCID http://orcid.org/0000-0002-4959-7069 E-mail: jonathan.sheppard@iww.uni-freiburg.de (email)
  • Morhart, Chair of Forest Growth and Dendroecology, Albert-Ludwigs-University Freiburg, Tennenbacher Straße 4, 79106 Freiburg, Germany ORCID 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
article id 1071, category Research article
Ursula Kretschmer, Nadeschda Kirchner, Christopher Morhart, Heinrich Spiecker. (2013). A new approach to assessing tree stem quality characteristics using terrestrial laser scans. Silva Fennica vol. 47 no. 5 article id 1071. https://doi.org/10.14214/sf.1071
Keywords: LIDAR; terrestrial laser scanner; tree stem quality assessment; cylinder approximation; bark defects
Highlights: Minimal deviations of the bark surface can be detected and visualized based on terrestrial laser scan data; Additionally the geometrical properties of bark scars and branched knots can be assessed; Two methods using two different approaches are presented: (1) a method using intensity data and (2) a method using bark surface models.
Abstract | Full text in HTML | Full text in PDF | Author Info
This paper presents an approach to assess and measure bark characteristics as indicators of wood quality using terrestrial laser scan data. In addition to the detection and measurement by use of the intensity information of the scan data a new approach was established. Bark surface models are calculated for each tree. They offer the representation of the bark as a height model. The reference is the tree stem approximated by a chain of cylinders. Minimal deviations of the bark surface can be detected and visualized and the geometrical properties of bark scars and branched knots can be assessed. Results of the measurement of 18 scars are presented using the two approaches: (1) a method using intensity data or (2) using bark surface models. The selection of the adequate approach depends on the stem characteristics. In a next step, methods for automatic measurement of bark scars will be developed.
  • Kretschmer, Chair of Forest Growth, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: ursula.kretschmer@iww.uni-freiburg.de (email)
  • 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

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