Phytophthora root disease: a new threat for cork oaks at Doñana National Park (south-western Spain) (Art.)

Abstract

The cork oak is an emblematic species of great ecological value in the ecosystem "stabilized sands" at Doñana National Park (south-western Spain): The current oak population mainly consists of big scattered individuals representing only a 10% of the forest that occupied the area three centuries ago and which was devasted by massive cutting. After the protection of the area as Biological Reserve forty years ago, all silvicultural practices such as cutting, pruning and cork extraction ceased. the population of mature trees is suffering a quick decline that threatens their survival. The main menace to the survival of cork oaks comes from Finally, we detected a new problem: the sudden decline of trees, which may die within a few months independently to the presence of nesting birds. Phytophthora cinnamomi has been consistently isolated from roots and rhizosphere of these trees and The cork oak is an emblematic species of great ecological value in the ecosystem ‘stabilized sands’ at Doñana National Park (south-western Spain). The current oak population mainly consists of big scattered individuals representing only a 10% of the forest that occupied the area three centuries ago and which was devastated by massive cutting. However, the high density of herbivores (deer, wild boar, cattle, horse) which eat almost all of the acorns and prevent young plants to grow and replace old trees. Additionally, a significant number of oaks are frequently occupied by a nesting colony of wading birds (storks, herons, spoonbills). These trees show signs of stress (defoliation), and eventually die much faster than trees not occupied. an important increment in the number and size of these foci is expected. In this way, proposals to monitoring the affected trees and preventive application of phosphonates by trunk injection have been exposed to the Park authorities.