Dinámica de la humedad del suelo bajo encinas decaídas y no decaídas en focos de Phytophthora cinnamomi

CORCOBADO, T., M. A. DELGADO, E. CUBERA, A. PEREZ, E. JUAREZ, G. MORENO, A. SOLLA. 2012. Soil water content dynamic under declining and non-declining trees in Phytophthora cinnamomi stands. Bol. San. Veg. Plagas 38: 157-165. Soil water table fluctuations, soil water content and fine roots abundance seem to play a role in the decline of oak forests in Iberia, especially if trees grow in Phytophthora cinnamomi infested soils. No experimental research has been conducted in the field, however, to test this hypothesis in mature trees. The study was performed in western Spain and included 101 Quercus ilex forest stands in which the soil water dynamic and the abundance of fine roots between declining and non-declining trees were compared. Exposure of roots to waterlogging (during 2 months maximum), annual fluctuations of the soil water table depth (about 3.5 m) or values of soil water content observed (about 25% vol during summer) could not explain alone the decline of trees. However, fine root density was about 16.2% lower in declining than in non-declining BOL. SAN. VEG. PLAGAS, 38, 2012 165 trees, and significantly lower in P. cinnamomi-infected trees than in non-infected trees (59.1 and 84.8 roots m-2, respectively; p < 0.001). Root damage caused by P. cinnamomi in combination with usual circumstances of waterlogging during bud-break period or water stress during summer will determine the health status of trees.