engleski

Assessment of possible ozone induced forest injury on Medvednica based on AOT40 index and ozone- induced visible injury

The phytotoxic effects of tropospheric ozone on plants are widely recognized. The aim of this study was to assess possible ozone induced injury on forests of mountain Medvednica. The mountain is located north of the city of Zagreb. Forests cover about 81% of the Medvednica area. Puntijarka station (988 m a.s.l.) on mountain Medvednica, once operated within the EUROTRAC/TOR and TOR-2 projects, was running continuously for two decades (1989- 2009) using automated ozone monitors based on UV absorption. Station Medvedgrad (593 m a.s.l.) and Bliznec (350 m a.s.l.) operated occasionally. The monitoring of ozone-induced visible injury was performed at 3 Light Exposed Sampling Site (LESS) Level II plots as part of ICP-Forests (Croatia joined it in 1987) - Činovnička livada, Medvedgrad and Medveščina. Due to frequent exceedance (85, 7 % for Puntijarka) of ozone critical levels for forest vegetation (10 ppm.h O3) the AOT40 index values indicate a high possibility of damage to plants by ozone on the middle and upper mountain areas (stations Puntijarka and Medvedgrad). These results would suggest ozone-induced visible injury. However symptoms of ozone damage on leaves of the observed forest tree species in most cases were not possible to confirm unambiguously. Only for the elevated plot Činovnička livada there were confirmed, clear and pronounced symptoms of ozone injury only in Ulmus glabra. Considering these results AOT40 index should be replaced by some other concept, perhaps ozone flux concept which will take into account the actual transfer of ozone into leaves and thus be able to more accurately determine the damage caused by ozone suffered by plants.

ozone ; Medvednica ; forest injury

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