Epidemiology of oak decline: spatial-temporal mortality pattern of oak in a Golestan chestnut-leaved oak forest (Case study: Qoroq forest park)

Evaluating the population density and spatial pattern of infected trees are one of the important criteria for selecting the management method and epidemiology of forest diseases. This study aimed at assessing the damage intensity and spatial-temporal mortality patterns of oak in Qoroq forest park, Golestan province. the health of oak trees was evaluated in seven transects by using quarter-point method in 2013 and 2014. The results showed that the rate of infection and decline of oak trees in Qoroq forest park has heterogeneous distribution, so in the western part of the park, damage intensity and rate of infection and mortality are higher. Initially the dead trees indicated strong spatial clustering at larger scales (900 m) and after a year, intensity of clustering was less pronounced so that at 200, 400, 600 and 800 m, weak clusters are formed. However the co-occurrence analysis of disease severity damage showed that newly infected trees and dead trees had a negative association and occurred in the clusters away from the dead trees, but the trees with high damage was strongly related to the mortality. The results can be a suitable model for planning conservation applications and protection of infected oak forests and monitoring the oak decline