Preliminary communication
Defoliation of Forest Trees in Croatia in the period 2006 – 2009
Nenad Potočić
orcid.org/0000-0002-5581-2976
; Hrvatski šumarski institut Jastrebarsko
Ivan Seletković
; Hrvatski šumarski institut Jastrebarsko
Abstract
In response to widespread concern that air pollution could affect forest condition, the International Co-operative Programme on the Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) was established by the Convention on Long-range Transboundary Air Pollution (CLRTAP) under the United Nations Economic Commission for Europe in 1985. Croatia joined the Programme in 1987. The advantage of monitoring is in obtaining a time series of data that enables correct deduction on the phenomena that, in this case, vary on annual basis.
Monitoring is conducted on two networks: Level I (so called bioindication plots at 16 x 16km distance) and basic network (4 x 4 km distance of plots). Defoliation, the key parameter for assessing forest ecosystem condition, is assessed according to ICP Forests Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests.
Defoliation is high in Forest Branch Offices Vinkovci, Zagreb, Delnice and Buzet, and low in Bjelovar and Koprivnica (Fig. 5). The high percentage of moderately to severely damaged trees in Forest Branch Office Delnice and Vinkovci is the result of intensive dieback of silver fir and pedunculate oak, respectively. In Forest Branch Office Buzet, a high percentage of moderately to severely damaged trees is the result of high defoliation values in almost all surveyed species.
In Forest Branch Offices Gospić and Senj, moderate to severe damage of silver fir trees in year 2009 is significantly lower that the corresponding value in the bioindication and basic plot network in Croatia, while it is somewhat higher in Forest Branch Offices Delnice and Ogulin.
Very high values of percentages of moderately to severely damaged trees of pedunculate oak in the year 2009 were present in Forest Branch Offices Požega, Zagreb, Našice and Osijek, and very low in Bjelovar and Koprivnica. Moderate to severe damage of beech is significantly higher than the value for Croatia in Forest Branch Offices Zagreb, Delnice and Senj, and lower in Bjelovar, Sisak, Karlovac and Našice.
The rising percentage of moderately to severely damaged trees of all species started in 2002, and for broadleaves in 2003. Conifers, on the other hand, have a decreasing trend of defoliation since 2006 (Tabs. 2–4).
Keywords
ICP Forests; condition of forest ecosystems; crown defoliation; Level I and basic network
Hrčak ID:
72323
URI
Publication date:
14.10.2011.
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