Metla Project 3478

Effect of stump harvesting on forest damage and saproxylic species

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Duration: 2007-2011   Keywords: Biodiversity, Coleoptera, Forest damage, Fuelfood, Hylobius abietis, Mechanical protection, Pine weevil
Research Programme: Bioenergy from Forests

Objectives

Heterobasidion root rot is a serious threat when regenerating Norway spruce and Scots pine stands in southern Finland. After final cutting of diseased stand the fungus is able to live in large stumps for several decades and infect trees of the next stand generation. Especially on sites, where site factors or high risk of browsing damage by elk limit the choice of resistant tree species, regeneration of the infected stand is problematic. Removal of infected stumps eliminates most inoculum from the site and reduces carry-over of the disease into the new stand. However, stump harvesting does not remove all the roots and broken pieces from the site. At present, it is not known whether these pieces of infected wood left in the ground have sufficient inoculum potential to infect the next tree generation.

Pine weevil Hylobius abietis causes significant economic losses in forestry by gnawing the bark and phloem of conifer seedlings and finally killing them. This insect is not a problem in natural forests but its potential to cause damage has increased along artificial regeneration of forests. Currently, small close clear cut areas, continuous logging activities and certain soil preparation methods create favourable conditions for pine weevil in Finnish forests. The storage of fresh logging residues and stumps attract pine weevils and may increase the capacity of pine weevil to damage the seedlings planted in regeneration site. Further, uprooting stumps may improve the moving of pine weevil and increase the incidence to reach the seedling.

The volume of dead wood in managed forests is very small as compared with natural forests. The small average volume of dead wood in managed forests is the main cause of declining and becoming threatened for a large number of saproxylic species. The volume of dead wood in the form of cut stumps and logging residues is higher than the volume of coarse woody debris (which is measured in the National Forest Inventory) when averaged over the whole rotation time of a stand. Therefore, the harvesting of stumps can affect the dead-wood pool and species dependent on it.

The aim of the project is to survey the amount of infectious material left on regeneration areas after stump harvesting and determine the risk of Heterobasidion infection and pine weevil damage of the subsequent spruce and pine stands. Potential risk factors associated with stump harvesting, such as development of fruit bodies of Heterobasidion on decayed stumps during the road-side storage and attraction of pine weevils due to storage piles will be assessed. Diversity of saproxylic species will be studied with the emphasis on changes in species abundance and occurrence as result of stump uprooting.

Project leader: Piri, Tuula
The Finnish Forest Research Institute, Vantaa Unit, PL 18, FI-01301 VANTAA, FINLAND
Phone: +358 10 211 2453 Telefax: +358 10 211 2103
E-mail: tuula.piri@metla.fi

Other researchers: Kilpeläinen, Jouni (2010), Siitonen, Juha, VA (2008,2011), Viiri, Heli, JO (2007-11)


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Updated 24.05.2012
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