Dendrochronological and dendroclimatological tree analyis of pedunculate oak ( Quercus robur L.) in virgin forest of Prašnik

Abstract

Kao dio međunarodnog projekta pod nazivom „Mixed severity disturbances as drivers of structural variability and carbon dynamics at the stand and landscape levels”, ovaj rad opisuje problematiku rasta i razvoja stabala hrasta lužnjaka (Quercus robur L.) na području prašume Prašnik. Nastoji se objasniti povezanost različitih stanišnih čimbenika promatrajući promjene u priraštanju godova. U radu se koriste i opisuju koncept i metodologija dendroklimatološkog istraživanja uz kratak pregled razvoja dendrokronologije kroz povijest te utjecaj klimatskih čimbenika na varijabilnost strukturnih i anatomskih elemenata, i to ponajprije utjecaj temperature i oborina na debljinski prirast stabala hrasta lužnjaka. Korištenjem dendroklimatološke metodologije i tehnike unakrsnog datiranja (cross-datinga), razvijena je osnovna referentna kronologija u duljini od 270 godina od 42 uzorka hrasta lužnjaka, sakupljenih u prašumi Prašnik 2015. godine. Sekundarnom analizom unakrsnog datiranja u COFECHA-i potvrdila se kvaliteta izmjere i svakom se godu pridružila stvarna godina njegovog nastanka. U ARSTAN programu izrađene su referentne kronologije (osnovna i rezidualna) i dobivena je statistička potvrda jačine populacijskog signala iz EPS i r-bar statističkih pokazatelja. S obzirom na razdoblje za koje su dostupni klimatski podaci (Cru TS 3.23) rezidualna kronologija izrađena u ARSTAN programu uspoređivana je s klimatskim podacima (temperaturom i oborinama) u razdoblju 1900.-2014. godine.As part of an international project Mixed severity disturbances as drivers of structural variability and carbon dynamics at the stand and landscape levels, this thesis describes the problematics of growth and development of pedunculate oak (Quercus robur L. in virgin forest (old-growth forest, rainforest) of Prašnik. The thesis tries to describe the connection of tree-ring growth with habitat factors (temperature, precipitation). The concept and history of dendrochronology is described as well. Using the methodology of dendroclimatology, tree-rings are compared to climate data to investigate their variability and mutual connection. Tree-rings are cross-dated to confirm the dating of each tree-ring and reference chronologies of pedunculate oak are developeded using PAST programing tool. Secondary statistical check of cross-dating and measurements is done in COFECHA program. Concerning the time period of available climate data (CRU TS – 1901.-2014.) and the replication issues (EPS and r-bar), mean residual reference chronology developed in ARSTAN program is compared to climate data (temperature and precipitation) in a time period of the last 114 years. Response function analysis shows negative correlation of temperature respone of tree-rings in April and July for pedunculate oak, while showing positive correlation with precipitation in period from Januar until April, meaning the high temperatures of April and July are decreasing diametar growth, while high levels of precipitation in first four months of the year are increasing it