ARBORICULTURAL AND DENDROECOLOGICAL ANALYSIS OF THE CONDITION OF HORSE CHESTNUT (Aesculus hippocastanum L.) TREES IN THE TOWN OF VELIKA GORICA

Abstract

U radu se analizira vitalitet, zdravstveno stanje, mehanička stabilnost i rast stabala divljeg kestena (Aesculus hippocastanum L.) na području grada Velike Gorice. Uz pomoć vizualno kontrolne metode (Visual Tree Assessment), obavljena je arborikulturna analiza biološkog (vitalitet) i mehaničkog (statičkog) stanja starih i mladih stabala. Procjena vitaliteta obavljena je na osnovi skale od 1–5 te prema Roloffovom modelu (0–3). Korelacijska analiza klimatskih čimbenika (temperature i oborina) i indeksne kronologije stabala divljeg kestena provedena je uz pomoć programa DENDROCLIM. Istraživana mlada stabala divljeg kestena imaju slične dendrometrijske varijable (promjer i visina stabla, polumjer krošnje, udaljenost stabala), dok su kod starih stabala vidljive razlike s obzirom na lokacije koje su uvjetovane različitom starošću stabala, zahvatima ovršavanja krošanja i uvjetima staništa. Prsni promjeri starih stabala statistički se značajno razlikuju s obzirom na istraživane tri lokacije. Istraživana mlada stabla divljeg kestena u parku imaju statistički značajno veći vitalitet od onih u drvoredu, što se može protumačiti boljim ekološkim uvjetima. Najbolji vitalitet pokazuju stara stabla u parku, a najlošiji u drvoredu kod željezničkog kolodvora, dok najbolji vitalitet po Roloffu imaju stabla u Zagrebačkoj ulici, a najlošiji u parku. Prema evidentiranim simptomima i greškama drva mladih stabala utvrđeno je manje postotno učešće kod stabala u parku u odnosu na drvoredna stabla. Kod starih stabala divljeg kestena najveće postotno učešće simptoma i grešaka drva zabilježeno je u Zagrebačkoj ulici i u blizini željezničkog kolodvora, dok je manji udio evidentiran kod parkovnih stabla. Vizualno kontrolnom metodom uz dodatnu provjeru rezistografom, utvrđena su dva stara stabala koje trenutno treba ukloniti zbog narušene mehaničke čvrstoće te sigurnosti ljudi i imovine. Dendrokronološkom analizom utvrđen je velik senzibilitet u radijalnom prirastu stabala (0,08–8,17 mm). Utvrđena je značajna pozitivna ovisnost radijalnog prirasta o prosječnim količinama oborina u proljeće, dok je limitirajući učinak utvrđen za maksimalnu temperaturu zraka u proljeće.The paper analyses vitality, health condition, mechanical stability and growth of horse chestnut trees (Aesculus hippocastanum L.) which represent one of the traditional urban green landmarks in the town of Velika Gorica. Following the Visual Tree Assessment protocol biological (vitality) and structural (static) condition of young and old horse chestnut trees was acquired. Vitality assessment was done according to scale 1 – 5 and Roloff model (0–3). Correlation analyses of climatic conditions (temperature and precipitation) and tree index chronology was conducted via DENDROCLIM software. Researched young trees of horse chestnut had similar dendrometrical variables (breast height diameter, tree height, crown radius, tree distance), while old trees showed difference in respect to location which was conditioned by different age of trees, crown topping and site conditions. Tree breast height diameters are statistically different when three research locations are compared. Younger trees growing in park manifested significantly higher vitality compared with those trees growing in tree alley which is explained by better general growing conditions. Best tree vitality was measured in old trees growing in park while the opposite side of the scale was represented in tree alley along the railway station, while best vitality according to Roloff model was measured in tree lane in Zagrebačka street and on the opposite side of the scale was represented by trees growing in park. According to the assessed symptoms and tree defects younger trees growing in park had smaller percent share in respect to younger trees growing in tree alley in Zagrebačka street. Highest percent share of given symptoms and tree defects at old horse chestnuts trees was assessed in Zagrebačka street and near the railway station while smaller percent share was recorded in park. Visual tree assessment with resistography revealed two of older trees which need to be removed due to their mechanical breakdown resulting with heightened risk on humans and property. Dendrochronological analysis revealed sensibility in radial increment of measured trees (0.08–8.17 mm). Significant positive correlation of radial increment with average spring precipitation and limiting effect of maximum spring air temperatures was determined