Occurrence and decay patterns of common wood‐decay fungi in hazardous trees felled in the Helsinki City

Abstract

To improve the management of ageing urban trees, the role of wood-decay fungi as potential causes of stem breakage was investigated among hazardous trees removed in the Helsinki City area during [2001][2002][2003][2004]. The study material comprised 194 trees, and included 76 Tilia spp. trees, 58 Betula spp. and 60 Acer spp. Thirteen species or genera of commonly occurring decay fungi were identified on the basis of fruiting bodies and pure cultures. The occurrence of the fungi was investigated in terms of frequency, visibility and as potential causes for stem breakage. Most hazardous fungi caused extensive horizontal decay in the stem; such fungi were Ganoderma lipsiense on Tilia and Acer, Phellinus igniarius on Acer, Inonotus obliquus and Cerrena unicolor on Betula and Kretzschmaria deusta on Acer, Tilia and Betula. Typically, Rigidoporus populinus was frequently present in weak fork formations on Acer trees. Agaric fungi (Pholiota, Armillaria, Pleurotus and Hypholoma) were frequently recorded but were of minor importance from the point of view of tree breakage hazard.

Comparison of general tree characteristics of less known oak species Quercus dalechampii Ten. and Quercus polycarpa Schur

“…Individuals of Q. polycarpa suffer from heart rot very much; the majority of them are affected so the amount of saw timber and its quality are considerably reduced. In addition, the heart rot of basal stem parts weakens their mechanical strength, which causes that windthrows and breakages occur significantly as described by several authors (Hennon 1995;Lewis, Lindgren 1999;Terho et al 2007). On the contrary, the majority of Q. dalechampii stems are not affected by wood-decay fungi, which means that in general they are much less susceptible to mechanical damage and have the wood of comparatively better quality.…”

“…The heart rot fungi are usually restricted to a non-living part of the tree, but they cause major volume losses of saw timber (Dai et al 2007). In addition, trees infected by heart-rot fungi become weakened structurally (Terho et al 2007) and are easily broken due to windthrow (Hennon 1995;Lewis, Lindgren 1999). However, decay fungi are important ecologically as they play an important role in gap formation and so facilitate an uneven-aged stand structure (Lewis, Lindgren 1999).…”

Susceptibility of silver birch pruning wounds to infection by white-rot fungus (Chondrostereum purpureum), a potential bioherbicide

“…The fungus is a common primary stem pathogen of woody plants in temperate regions and is present during early (Brooks andMoore 1926, Rayner 1977) and later stages of the decay process (Terho et al 2007). At our field site, we left 81 of 210 experimental trees intact in order to study the decay process in inoculated and control trees over a longer period of time.…”

Grading of Parameters for Urban Tree Inventories by City Officials, Arborists, and Academics Using the Delphi Method

“…Similarly, the use of Vitality (ranked 2), Hazard class (ranked 4), and Presence of fruit bodies of fungi (ranked 6) in the scientific literature supports their high ranking (Terho and Hallaksela 2008;Terho et al 2007). However, there were some outliers.…”