Commission Implementing Decision of 12 December 2011 on an additional Union financial contribution for 2006 and 2007 to cover expenditure incurred by Portugal for the purpose of combating Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle et al. (pinewood nematode) (notified under document C(2011) 9247) (Only the Portuguese text is authentic) (2011/851/EU)