engleski

Eco-physiological response of Common beech (Fagus sylvatica L.) under changed stand and climate conditions in Croatia

Common beech (Fagus sylvatica L.) is a dominant broadleaved tree species in Croatia. In the last three decades, silver fir (Abies alba Mill.) dieback of catastrophic proportions in Croatia, partly caused by climate change, has led to a major expansion of pure beech over former beech – fir sites. The area of beech – fir forets has been reduced and the proportion of pure beech forets has increased due to natural regeneration of beech in sun – exposed sites. Although beech is a species of wider ecological amplitude in comparison with fir, this contradicts recent forestry practices (regeneration under canopy shelter) and the defined ecological requirements of beech (sensitivity to sunburn, shade tolerance). Climate change is perhaps the most critical factor facing the current generation of land managers who are concerned about the future condition of natural and managed ecosystems. The results of two seperate experiments, a nursery experiment and a case study, will be discused in the light of the ecophysiological status of beech in changed stand and climate conditions. The influence of climate and relief properties on the crown conditions of beech on Medvednica massif was monitored in the period 2004 – 2006. Climate and relief properties were found to significantly influence the crown conditon of beech trees. To determine the ecophysiological response of beech seedlings to full sunlight conditions, a nursery experiment was established with three fertilization treatments (2, 4 and 6 g of Osmocote Exact per 1 liter of substrate) to simulate various soil fertility conditions (poor, adequate and excessive availability of nutrients) in Hajderovac nursery. Height, diameter and biomass of seedlings increased with fertilizer dose. Concentrations of N, P and K increased with fertilizer dose, while Ca and Mg concentrations showed negative effects of overfertilization at the highest fertilizer dose. Root length, surface area and number of root tips were highest in the intermediate treatment while roots were least developed at the highest fertilizer dose. Assimilation rates of seedlings corresponded well with leaf mass (r2=0, 59), leaf (r2=0, 44) and root total nitrogen (r2=0, 58) and total leaf phosphorus (r2=0, 45).

Defoliation; nutrients; photosynthesis; biomass; root

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