COMPARATIVE INVESTIGATIONS OF CUTICULAR PERMEABILITY OF CONIFER NEEDLES FROM HEALTHY AND DAMAGED TREES

Using pentachlorophenol (PCP) and conifer needles, rates of cuticular PCP uptake and effective leaf surface areas were measured, and PCP permeances of the cuticular membranes were calculated. Needles from healthy and damaged conifer trees of the species Picea abies (L.) Karst., Pinus sylvetris L. and Abies alba Mill. were investigated. Significant differences of the rates of cuticular uptake, effective leaf surface areas and permeances of the cuticular membranes between healthy and damaged trees were not evident. Thus, it must be concluded that damaged cuticular transport barriers of the needles cannot have contributed to the damage symptoms observed with the trees investigated in this study. However, it was found that increasingly older spruce needles had significantly higher permeances, indicating a decrease of cuticular barrier properties with needle age. Additionally, due to larger effective leaf surfaces spruce needles of higher altitudes (1100 m above sea level) possessed higher rates of cuticular transport compared to needles from lower altitudes (400 m above sea-level). Therefore, these findings might help to understand why older needles and trees growing in higher geographical sites are more sensitive to detrimental environmental influences causing symptoms of novel forest decline.