engleski

Marija Gradečki-Poštenjak1, Sanja Novak Agbaba1

Summary Pedunculate oak is a climatogenic species and it constitutes principal forest communities. If some ecological factor in its habitat is altered, due to unfavorable biotic and abiotic factors, pedunculate oak cannot adjust fast and it suffer substantial damage over the years. Current ecological imbalance can be recognized as main reason in oak dieback. Deterioration sings become visible and they are reflected in decline of tree vitality, unsettled and low yield and also remote natural forest regeneration. Variability in acorn production is the result of sinecological and genetic factors. Acorn yield is the most influenced by maternal trees. Pedunculate oak belongs to subgenus Lepidobalanu and has tendency of periodical yield, with return of every 4 years (abundant), and every 2 years (normal). Research on acorn production have been carried out in „Spačvanski bazen“ area in period from 2006 to 2010. Main research goal was to monitor acorn crop according to quality and quantity, in stands of different age - middle aged, older and old forests, so production potential could be identified. Experimental plots were established in 2006. Acorn production assessment- acorn growth and development, was monitored by cone-shaped acorn-collecting traps method. Acorn-collecting traps were placed beneath the canopy of selected trees of different crown damage classes. In the crop years acorns were collected, and in the spring next year seedlings were counted. Collected materials were analyzed in the Laboratory for testing seed quality. Seed quality was tested accordingly to ISTA methodology. Monitoring of growth and development of acorns by acorn-collecting traps method (Table 3) proved the fact that most matured and normally developed acorns came from older stands, and the least in old stands. Regarding crown damage degrees the most matured acorns came from crown damage class 2A, and least from class 2B and 3. First acorn crop was in 2006 and second in 2010. In year 2006 acorn crops was more abundant than in 2010. The best acorn crop was in old stands (on average 269 kg/ha), the worst was in middle aged forests (41 kg/ha). With reduction of tree age came reduction in acorn crop. Yield in 2010 was the best in older forests (90 kg/ha) and the worst in middle aged forests (30 kg/ha). Average number of seedlings was at its peak in old forests (40000 pts/ha), the worst in older forests (16167 pts/ha). Periodicity in acorn production during the period of 11 years in the management unit Slavir and on the area of Forest Administration Office Vinkovci followed same trend in 11 years time. Annual acorn production was monitored for 11 years and crop years were: 2000, 2002, 2003, 2006 and 2010. Average quality values for acorns harvested on experimental plots were: 2006: viability 83%, insect’s presence 12% 1000 seed weight 5384 g, and number of acorn/kg 185 pts/kg ; yield. In 2010 were: germination capacity 71%, rotten and decayed seed 29%, 1000 seed weight 4933 g, and number of acorn/kg 203 pts/kg. Based on study of acorn periodicity yielding and quality crops conclusions can be made: degree of crown defoliation significantly influences quantity of produced acorns, old forests produced the most acorns, seed production decreased with age. Number of seedlings shows us that the most quality acorns remains in crowns and its fells after commercial seed collecting are completed. In middle aged forest number of seedlings in double the quantity than other investigated stands, acorn maturation is longest, and acorn fells on ground later. Monitoring of dynamics and seed production quantity during 11 years, crop years occurs significantly every 2 to 3 years and they differ in quantity. During that period were 5 masting years. Abundance of yield represents production potential of stands. In old stand abundant acorn crops is identified with average yield of 269 kg/ha or 114748 pts of acorn /ha. Seed production abundance is far below what is considered as abundant, therefore significant effort is required for preserving acorns in crowns after maturing and felling on the ground.

pedunculate oak; acorn production; acorn quality; acorn-collecting traps method; stand production potential

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