Influence of the forest cultures on nutrient stocks in the forest floor on "Đurđevački peski" area

Biogene i korisne elemente nazivamo biljnim hranivima. Većina hraniva koje biljne vrste usvoje naposljetku se vrate u tlo, odnosno na tlo (šumska prostirka). Pošumljavanjem područja Đurđevačkih pijesaka ubrzana je prirodna sukcesija, a najveći udjel zauzimaju kulture običnog bora (Pinus sylvestris L.), crnog bora (Pinus nigra Arnold) i bagrema (Robinia pseudoacacia L.). Sve kulture ispunile su svoj primarni cilj, učvrstile su tlo i spriječile premještanje istog eolskim putem. Ovim istraživanjem nastojalo se kvantificirati i usporediti akumulirane zalihe hraniva u šumskoj prostirci ekstrakcijom zlatotopkom, u kulturama običnog bora (Pinus sylvestris L.), crnog bora (Pinus nigra Arnold) i bagrema (Robinia pseudoacacia L.) na području Đurđevačkih pijesaka te ih usporediti s kontrolnim plohama bez šumske vegetacije. Rezultati su pokazali da su istraživane kulture pozitivno utjecale na povećanje zaliha hraniva u odnosu na kontrolne plohe bez šumske vegetacije. Zalihe istraživanih hraniva na kontrolnim plohama 200 do 300 % su manje u odnosu na zalihe hraniva u šumskim kulturama. Zalihe hraniva u borovim kulturama 50 do 100 % su veće u odnosu na kulture bagrema, izuzev kalcija. Prema provedenome istraživanju izvodi se zaključak kako su šumske kulture povoljno utjecale na status zalihe hraniva na području Đurđevačkih pijesaka.Biogenic and useful elements are called plant nutrients. Most of the nutrients adopted by plant species eventually return to the soil, or to the soil (forest mat), that is. The afforestation of the Đurđevac sands has accelerated the natural succession, and the largest share is occupied by the cultures of Scots pine (Pinus sylvestris L.), black pine (Pinus nigra Arnold) and acacia (Robinia pseudoacacia L.). All cultures fulfilled their primary goal, strengthened the soil and prevented its movement by the Aeolian processes. The aim of this study was to quantify and compare the accumulated nutrient reserves in the forest floor by extraction with aqua regia, in cultures of Scots pine (Pinus sylvestris L.), black pine (Pinus nigra Arnold) and acacia (Robinia pseudoacacia L.) in the area of Đurđevac sands, and to compare them with control plots without forest vegetation. The results showed that the studied crops had a positive effect on increasing nutrient stocks compared to control plots without forest vegetation. The stocks of researched nutrients on the control plots are 200 to 300% smaller in relation to the nutrient stocks in forest crops. Nutrient stocks in pine crops are 50 to 100% higher than in acacia crops, except for calcium. According to the conducted research, it is concluded that forest crops have had a favorable effect on the state of nutrient stock in the area of Đurđevac sands