The effect of white mistletoe (Viscum album subsp. abietis (Wiesb.) Abromerit) on diameter increment in Kazdağı fir stands

Abstract

In this study, the effects of white mistletoe (Viscum album subsp. abietis (Wiesb.) Abromerit) on diameter increment in Kazdağı fir (Abies nordmanniana subsp. equi-trojani (Asc. & Sint. ex Boiss.) Coode & Cullen) stands distributed in Kastamonu region of Turkey were investigated. For this purpose, a total of 183 sample trees (77 healthy (uninfected) and 106 infected) were selected from mistletoe-infected stands. Mistletoe infected sample trees were classified according to the mistletoe intensity groups as lightly-, moderately- and heavily-infection levels. Increment cores were taken from the sampled trees, and annual ring widths were measured for evaluation period which is the last 30 years of sample trees. Underbark diameter increments were determined for the last 10, 20 and 30 years and for also last three 10-year periods. Mistletoe infected trees were compared to healthy trees according to the mean diameter increments. As a result, it was determined that there were statistically significant differences between underbark diameter increments of infected and uninfected trees. Increment losses of infected trees compared to uninfected trees were calculated as 21%, 28% and 33% for the last 30, 20 and 10 years, respectively. Similarly, significant differences were also observed for the last three 10-year periods and it was revealed that the underbark diameter increment losses were 11%, 24% and 33%, respectively. The results show that increment losses increase gradually with infection and the presence of white mistletoe negatively affects diameter increments with an increasing acceleration from the past to the present.