Increased Long-Term Threat from Climate Change to Susceptibility of Sitka Spruce Plantations Growing in Peat Soils in Upland UK to Root and Butt Rotting Attacks by Heterobasidion annosum

The recommendations made in 2002 (Pratt 2003) for prophylactic stump treatment in UK forests against Heterobasidion annosum Fr. Cke. (hereafter H. annosum) on Sitka spruce (Picea sitchensis Bong. Carr.) were based on over 50 years continual research by the UK Forestry Commission into the risk posed by this destructive pathogen. They were predicated on the silvicultural and environmental conditions that were relevant during the second half of the 20th century: a period of expansion of upland forestry as techniques for establishing commercial crops on peat-dominated soils improved. The almost certain onset of climate-change and its effect on the physical, chemical and biological nature of peat, which in 2002 was assessed as of low risk from H. annosum, now requires to be taken into account and the need for new research into this threat examined. This paper reviews the research that underpinned the 2002 recommendations.

Keywords: Heterobasidion Annosum, Sitka Spruce, Climate Change, Peat, Uk.