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.

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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

article id 426, category Research article

Uwe Schmitt, Risto Jalkanen, Dieter Eckstein. (2004). Cambium dynamics of Pinus sylvestris and Betula spp. in the northern boreal forest in Finland. Silva Fennica vol. 38 no. 2 article id 426. https://doi.org/10.14214/sf.426

Keywords: birch; boreal forest; Scots pine; cambium dynamics; wood formation; pinning technique; light microscopy

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Wood formation dynamics of pine and birch along a south-north transect in Finnish Lapland were determined by the pinning technique. For all trees at all sites a more or less sigmoid shape of the wood formation intensity is characteristic with a slow beginning, a faster growth in the middle and a decreasing activity towards the end of the vegetation period. Wood formation of pine started at sites 1–3 (southern sites) in the second week of June and at sites 4 and 5 (northern sites) only in the last week of June, whereas wood formation ended within the first half of August. Wood formation of birch started in the second half of June and ended around the beginning of August. First cells were laid down by pine and birch when the temperature sum had reached the level of 85 to 90 degree days and 110 to 120 degree days, respectively. The intensity of wood formation in pine was highest in July, in birch within two weeks in the middle of July. Wood formation in pine lasted for about seven weeks at the southernmost and about six weeks at the northernmost site. In birch, the duration of wood formation was about five weeks at the southernmost site and around three weeks at the other sites.

Schmitt, Federal Research Centre for Forestry and Forest Products, Institute for Wood Biology and Wood Protection, and University of Hamburg, Chair for Wood Biology, Leuschnerstr. 91, P. O. Box 800209, D-21002 Hamburg, Germany E-mail: u.schmitt@holz.uni-hamburg.de
Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Station, Box 16, FI-96301 Rovaniemi, Finland E-mail: rj@nn.fi
Eckstein, Federal Research Centre for Forestry and Forest Products, Institute for Wood Biology and Wood Protection, and University of Hamburg, Chair for Wood Biology, Leuschnerstr. 91, P. O. Box 800209, D-21002 Hamburg, Germany E-mail: de@nn.de

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