Search

Mestni in primestni gozdovi sestavljajo pomembne habitate za ohranjanje biotske pestrosti v mestih. V tem članku predstavljamo metodo za uporabo muh trepetavk kot kazalnikov biotske pestrosti v urbanih gozdnih habitatih. To metodo smo uporabili za oceno gozdnih habitatov v treh primestnih in mestnih gozdovih ter jih primerjali s podeželskimi gozdovi v Sloveniji. Kot mestni gozd je bil izbran Rožnik (Ljubljana), kot primestni gozd sta bila izbrana Mestni log (Ljubljana) in Brdo (Kranj), kot podeželske gozdove v različnih ekoloških regijah v Sloveniji pa smo izbrali osem gozdnih območij. V teh gozdovih smo primerjali bogatost gozdnih vrst muh trepetavk in njihovo vrstno sestavo glede na biološke lastnosti v izbranih mestnih, primestnih in podeželskih gozdovih. Poleg tega smo spremljali tudi odziv vrstne pestrost muh trepetavk glede na različne vremenske razmere med posameznimi leti. Število vrst z raziskanimi biološkimi lastnostmi v mestnih in primestnih gozdovih je bilo v podobnem razponu kot v podeželskih gozdovih. Število saproksilnih vrst je bilo večje v mestnih in manjše v primestnih gozdovih kot v podeželskih gozdovih. Deleži vrst z različnimi načini prehranjevanja in različnim trajanjem razvoja so bili podobni med mestnimi, primestnimi in podeželskimi gozdovi. Deleži vrst, katerih razvoj traja manj kot dva meseca ali več kot eno leto, ter deleži plenilskih vrst so bili podobni v mestnih in primestnih gozdovih, ne pa tudi v podeželskih gozdovih. Vrstna sestava drugih bioloških lastnosti se je med primestnimi in mestnimi ter podeželskimi gozdovi razlikovala. Bogatost vrst in njihova številčnost sta pokazali velike razlike v fenološkem razvoju muh trepetavk v letih 2012 in 2013. Te razlike so povezane z razlikami v minimalni temperaturi zraka v teh letih. Rezultati so obravnavani v povezavi z gospodarjenjem z mestnimi gozdovi, primernostjo muh trepetavk kot kazalnika biotske pestrosti in možnostjo za razširitev predlagane metodologije na druge skupine vrst. Urban and peri-urban forests are important habitats for maintaining biodiversity in cities. In this paper, we report a method for using hoverflies as biodiversity indicators in urban forest habitats. As a case study, forest habitats in three peri-urban and urban forests were assessed and compared to rural forests in Slovenia. Rožnik (Ljubljana) was chosen as the urban forest site, Mestni log (Ljubljana) and Brdo (Kranj) were chosen as the peri-urban sites, and eight sites were chosen in rural forests in different ecoregions in Slovenia. Forest hoverfly species richness and the species composition of different biological traits were compared between the peri-urban forests, urban forest and rural forest sites. In addition, species richness was assessed for changes in response to weather conditions between years. The number of species with the investigated traits in the urban and peri-urban forests was within the range of the number of species observed in the rural forests. The number of saproxylic species was higher in the urban forest but lower in the peri-urban forests compared to the rural forests. The proportions of species with different feeding modes and different development times were similar between the peri-urban, urban and rural forests. The proportions of species with development times of less than 2 months or more than 1 year and of predatory species were similar in the urban and peri-urban forests but higher in the rural forests. The species composition of the other biological traits differed between the peri-urban, urban and rural forests. Species richness and abundance displayed large differences in phenological patterns between 2012 and 2013; these differences are related to differences in the minimum temperature for these years. The results are discussed in relation to forest management in urban forests, the usefulness of hoverflies as a biodiversity indicator and possible extrapolation to other species groups. Bibliografija: str. 38-39. Izvleček ; Abstract.

V prispevku predstavljamo proces in rezultate določitve korekcijskih količnikov za pretvorbo rezistografskih gostot, izmerjenih na stoječih drevesih, v osnovno gostoto lesa na primeru bukve (Fagus sylvatica L.), puhastega hrasta (Quercus pubescens Willd.) in črnega bora (Pinus nigraArnold.). Korekcijski količniki so bili določeni na podlagi sveže odžaganih kolutov, ki so bili povrtani z rezistografom. Kolute smo stehtali, izmerili njihovo prostornino ter jih posušili do absolutno suhega stanja. Iz zbranih podatkov smo nato izračunali osnovno gostoto lesa ter korekcijske količnike med osnovno in rezistografsko gostoto. V raziskavo je bilo zajetih 59 kolutov. Aritmetična sredina vseh izmerjenih količnikov znaša 1,41, vrednosti 95 % intervala zaupanja pa znašajo od 1,38 do 1,46. Razlike med drevesnimi vrstami so statistično neznačilne. Rezistografska gostota relativno dobro odraža osnovno gostoto kolutov (Pearsonov korelacijski koeficient = 0,91 p < 0,001), kar nakazuje na relativno dobro povezanost osnovnih gostot kolutov z rezistografskimi gostotami. Dobljeni rezultati so ključnega pomena za nadaljnji razvoj področja merjenja dejanskih gostot lesa v stoječih drevesih na hiter in relativno nedestruktiven način. In this article, we present the process and results of the determination of correction quotients for conversion of resistograph densities, measured in standing trees, into basic wood densities on the example of beech (Fagus sylvatica L.), pubescent oak (Quercus pubescens Willd.), and black pine (Pinus nigra Arnold.). The correction quotients were defined based on freshly sawn-off stem disks drilled with resistograph. We weighted the stem disks, measured their volume, and dried them to the absolutely dry state. From the gathered data, we then calculated basic wood density and correction quotients between the basic and resistograph density. The research comprised 59 stem disks. The arithmetic mean of all measured quotients amounts to 1.41, and the values of the 95 % of trust intervals amount from 1.38 to 1.46. The differences between the tree species are statistically insignificant. The resistograph density reflects the basic density of the reels (Pearson correlation coefficient = 0,91 p < 0,001) relatively well, which indicates a relatively good connection of the basic densities of the reels with their resistograph densities. The obtained results are crucial for further development of the field of measurement of actual wood densities in standing trees in a fast and relatively non-destructive way

V prispevku je predstavljen primer raziskave o variabilnosti kakovosti lesa različnih drevesnih vrst v slovenskih gozdovih. Meritve gostote, ki je eden glavnih pokazateljev kakovosti lesa, bodo služile za izdelavo podatkovne baze za oceno prostorske variabilnosti kakovosti lesa v Sloveniji. Zanesljivih in objektivnih podatkov o kakovosti lesa v naših gozdovih je relativno malo. Takšne baze so na ravni Slovenije izjemno pomembne, saj omogočajo vpogled v kakovost lesa, ki bo v prihodnje na voljo kot surovina na trgu za domačo lesno industrijo. Podobne baze bodo pomembne za izračun količine vezanega ogljika v nadzemni in podzemni biomasi za Slovenijo, hkrati pa bodo zbrani podatki služili tudi kot izhodišče za nadaljnje analize kakovosti lesa, zlasti mehanske lastnosti, ki so ključne pri uporabi lesa za konstrukcijske namene. Lastnosti in razpoložljivost lesa ekonomsko pomembnih drevesnih vrst so osnova za razvoj gozdno-lesne verige glede novih tehnologij, razvoja novih biomaterialov in potenciala rabe lesa različnih kakovosti z optimalnimi izkoristki. This article presents an example of the research on the variability of wood quality of diverse tree species in Slovenian forests. Measurements of density, which is one of the grade-determining properties of wood quality, will serve for making a database for spatial variability of wood quality in Slovenia. There are relatively few reliable and objective data on wood quality in our forests. Such databases are extremely important on the Slovenian level since they enable insight into the quality of wood which will be available as a raw material for the national wood processing industry on the market in the future. Similar databases will be important for the calculation of the quantity of carbon, locked in the above-ground und under-ground biomass, for Slovenia at the same time, the acquired data will also serve as a starting point for further wood quality analyses, above all its mechanical characteristics which are crucial in the use of wood for construction purposes. Characteristics and availability of wood of economically significant tree species form the basis for the development of the forest-wood chain regarding new technologies, development of new biomaterials, and potential of the use of diverse quality wood with optimal efficiency.