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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. 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. |
