31. Daily climate data reveal stronger climate-growth relationships for an extended European tree-ring networkJernej Jevšenak, 2019, original scientific article Abstract: An extended European tree-ring network was compiled from various sources of tree-ring data from Europe, northern Africa and western Asia. A total of 1860 tree-ring chronologies were used to compare correlation coefficients calculated with aggregated day-wise and month-wise mean temperature, sums of precipitation and standardised precipitation-evapotranspiration index (SPEI). For the daily approach, climate data were aggregated over periods ranging from 21 to 365 days. Absolute correlations calculated with day-wise aggregated climate data were on average higher by 0.060 (temperature data), 0.076 (precipitation data) and 0.075 (SPEI data). Bootstrapped correlations are computationally expensive and were therefore calculated on a 69.4% subset of the data. Bootstrapped correlations indicated statistically significant differences between the daily and monthly approach in approximately 1% of examples. A comparison of time windows used for calculations of correlations revealed slightly later onset and earlier ending day of the year for the daily approach, while the largest differences between the two approaches arise from window lengths: Correlations calculated with day-wise aggregated climate data were calculated using fewer days than the monthly approach. Differences in the onset and ending dates of periods for the daily and monthly approaches were greater for precipitation and SPEI data than for temperature data.
Keywords: tree rings, dendroclimatology, tree-ring network, daily climate data, climate-growth relationships, dendroTools
Published in DiRROS: 21.08.2019; Views: 2379; Downloads: 1114
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32. Patterns of tree microhabitats across a gradient of managed to old-growth conditions : a case study from beech dominated forests of South-Eastern SloveniaKristina Sever, Thomas Andrew Nagel, 2019, original scientific article Abstract: An inventory of tree microhabitats was done in two unmanaged forests (Kobile and Ravna gora forest reserves) and one managed beech forest in SE Slovenia. The purpose of this study was to determine the influence of forest management, natural disturbances, and tree characteristics on microhabitat patterns. Forest structure and microhabitats were recorded in systematically placed plots (500 m2 in size) across each area. In total, we inventoried 849 trees on 54 plots and 1833 tree microhabitats. The results showed that forest management had no significant influence on the abundance of microhabitats per tree, but there were differences regarding microhabitat type between managed and unmanaged sites. There were substantially more microhabitats related to standing dead and live habitat trees in unmanaged forest (e.g. woodpecker cavities, insect galleries and bore holes, branch holes, dead branches and fruiting bodies of fungi), whereas in managed forests there were more tree microhabitats related to management (e.g. exposed heartwood, coarse bark, and epiphytic plants). The results also indicate that disturbance, tree diameter, vitality, and species influence the density, diversity, and occurrence of tree microhabitats.
Keywords: forest management, biodiversity, tree microhabitats, beech forests, old-growth, veteran tree, natural disturbance, dead wood
Published in DiRROS: 08.07.2019; Views: 7178; Downloads: 3062
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33. O rastnih funkcijahAnton Cedilnik, 1979, original scientific article Abstract: Članek ima namen z matematičnega stališča osvetliti lastnosti funkcij, ki jih gozdarji, agronomi in biologi uporabljajo za opis rasti nekaterih količin, kot višinska, debelinska, prostorninska rast dreves v odvisnosti od časa in podobno. Navadno uporabljajo za ponazoritev teh procesov elementarne, odsekoma analitične funkcije, ker na takih lahko uporabimo metode aproksimacije eksperimentalnih podatkov. Vendar take funkcije le grobo kažejo dejanska dogajanja v majhnih intervalih neodvisne spremenljivke. Zato bi bilo treba postaviti trdnejše temelje in kriterije za določevanje tipov funkcij, ki bi bile primerne za opisovanje katerih koli pojavov te vrste. Ta študija je poskus v tej smeri.
Keywords: matematika, gozdarstvo, rastna funkcija, biološka rast, karakteristična funkcija, subjektivni čas, rast drevesa, mathematics, forestry, growth function, biological growth, characteristic function, subjective time, growth of a tree
Published in DiRROS: 12.07.2017; Views: 4659; Downloads: 1959
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34. Prodanova rastna funkcijaAnton Cedilnik, 1983, original scientific article Abstract: V sestavku so zbrane formule o rastni funkciji ▫$y=x^2/(a+bx+cx^2)$▫ pri poljubni izbiri koeficientov ▫$a,b,c$▫. Dodanih je nekaj napotkov za prilagajanje te funkcije numeričnim podatkom.
Keywords: matematika, gozdarstvo, Michail Prodan, rastna funkcija, aproksimacija, mathematics, forestry, Michail Prodan, growth function, approximation
Published in DiRROS: 12.07.2017; Views: 4610; Downloads: 1945
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35. Influence of moisture, temperature and growth medium on Cenangium dieback of pine (Cenangium ferruginosum Fr., Ascomycotina)Dušan Jurc, Maja Jurc, 1997, original scientific article Keywords: Cenangium dieback of pines, forest dieback, fungi, Cenangium ferruginosum Fr., temperature, moisture, growth medium
Published in DiRROS: 12.07.2017; Views: 4473; Downloads: 1910
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