engleski

Dieback of silver fir (Abies alba Mill.) in Gorski Kotar in correlation with precipitation and temperature

Silver fir is the most widely distributed and the most important commercial conifer species in Croatia. However, it is also the most threatened. The first records of its dieback in Croatia date from the beginning of the 20th century. Dieback has since evolved into a worrying phenomenon and a significant forestry problem. Dieback of silver fir is attributed to different causes. The objective of this work is to present the dynamics and intensity of silver fir dieback and establish the correlation between tree dieback and climatic factors in the area of two management units in Gorski Kotar. The data collected from two management units in Gorski Kotar (management units Brloško and Ravna Gora) over a ten-year period relate to dead trees of silver fir across the entire management unit area. The management units of Brloško and Ravna Gora epitomize a typical area of fir forests in Croatia. Regression models were used to obtain data on temperature and precipitation quantity for each compartment /subcompartment. Linear correlation coefficients were applied to establish the correlation between dieback intensity and climatic factors. The dynamics of tree dieback was analyzed on the basis of tree number and volume. There was a statistically significant increase in air temperature values in relation to the normal series of 1961 – 1990 in the study area. Precipitation decrease was also present, but it was not statistically significant. Considerable dieback of fir trees was recorded on the edge of the distribution range and in stands with a disturbed selection structure. A strong correlation was also found between air temperature, precipitation and growing stock of silver fir and dieback intensity. The paper also discusses the already familiar causes of silver fir dieback.

silver fir; dieback; dieback intensity; temperature; precipitation

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