Effects of the pathogenic fungus Melampsorella caryophyllacearum on radial growth of Abies alba

Abstract

Long-term damages caused by fungi on tree radial-growth and its interaction with climate have been little studied. The incidence and the severity of damage caused by the pathogenic fungus Melampsorella caryophyllacearum on Abies alba in three plots sampled in the Irati forest (Western Pyrenees, Navarra) were quantified. The radial growth of 15 symptomatic trees and 15 asymptomatic trees using dendrochronological techniques were compared. The relationships between monthly climatic data (mean maximum temperature, precipitation) and radial growth of symptomatic and asymptomatic trees were established to determine the different responses of growth to climate between both types of individuals. Radial growth was significantly lower in symptomatic than in asymptomatic trees since the 1980’s when a higher frequency of traumatic resin ducts was detected. Different response functions according to the symptomatology of trees were not observed. The radial growth of A. alba was positively correlated to November mean maximum temperatures of the year prior to growth, and to February and April mean maximum temperatures of the year of growth. Negative relationships between growth and higher September mean maximum temperatures during the year before the tree-ring was formed, and with March and August mean maximum temperatures during the year of tree-ring formation were found. Finally, the radial growth of A. alba was also positively correlated to July precipitation during the year of growth.