Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Can Phytophthora quercina have a negative impact on mature pedunculate oaks under field conditions? | Ann. For. Sci. 63 2006 661-672 INRA EDP Sciences 2006 DOI forest 2006047 661 Original article Can Phytophthora quercina have a negative impact on mature pedunculate oaks under field conditions Ulrika JoNSSON-BELYAZIO Ulrika ROSENGREN Plant Ecology and Systematics Department of Ecology Ecology Building Lund University 223 62 Lund Sweden Received 26 September 2005 accepted 10 March 2006 Abstract - Ten oak stands in southern Sweden were investigated to evaluate the impact of the root pathogen Phytophthora quercina on mature oaks under field conditions. Phytophthora quercina was present in five of the stands while the other five stands were used as controls to verify the effect of the pathogen. In each stand a healthy a moderately declining and a severely declining tree were sampled. Fine-root length and nutrient status of each tree were analyzed and the chemistry of the soil surrounding each tree was determined. The results showed that P quercina can cause substantial reductions in the fine-root length of mature trees under natural conditions. The impact of the pathogen varied depending on tree vitality and season being most pronounced for declining trees after an unusually dry summer. Despite the significant reduction in live fine-root length of declining trees in Phytophthora-infested stands no consistent effects were found on the nutrient status of trees. Based on the significant impact of the pathogen on the fine-root systems of declining trees we suggest that P. quercina contribute to oak decline in southern Sweden at the sites where it is present. No explanation is currently available for the decline of trees in non-infested stands but the lack of symptoms of root damage indicate together with the extensive root growth of declining trees that root pathogens are not involved in the decline at these sites. Quercus robur Phytophthora quercina root vitality soil chemistry nutrient status Résumé - Phtytophthora quercina peut-il avoir un effet negatif sur les
