The impact of the urban-rural gradient of the city of Varaždin on the flora and representation of invasive plants

Istraživanjem utjecaja urbanizacije na floru i udio invazivnih biljaka na području Varaždina zabilježeno je 773 svojti vaskularnih biljaka. Brojem svojti najzastupljenije su porodice Asteraceae s.l. (11,51%), Poaceae (7,76%) i Fabaceae (5,82%). Među životnim oblicima prevladavaju hemikriptofiti (43,21%), a od flornih elemenata euroazijske biljke (32,21%). Zabilježeno je 18 strogo zaštićenih vrsta i 18 vrsta s nekom od kategorija ugroženosti. Značajna je zastupljenost alohtonih biljaka (18,11%) od kojih najveći dio potječe iz Amerike (37,14%), većinu čine neofiti (70,71%), a 30,71% pokazuje invazivni karakter. Većina alohtonih svojti unesena je namjerno (73,57%) i nije udomaćena na istraživanom području (52,86%). Najveći broj svojti dolazi na ruderalnim staništima i u ruralnoj zoni grada na kojima dolazi i najviše invazivnih svojti. Najveći nivo invazije pokazuju snažno antropogenizirana i vlažna staništa. Analiza flore Varaždina po staništima i zonama urbaniteta pokazuje da na sastav flore više utječe tip staništa i jačina antropogenog utjecaja nego razina urbanizacije.During investigation of the impact of urbanization on the flora and representation of invasive plants in Varaždin 773 vascular plant species were recorded. The most represented families are Asteraceae s.l. (11.51%), Poaceae (7.76%) and Fabaceae (5.82%). Hemicryptophytes prevail among life forms (43.21%), whereas Eurasian plants prevail among floral elements (32.21%). 18 strictly protected taxa and 18 threatened taxa were recorded. There is a significant representation of alien plants (18.11%), most of which originates from America (37.14%), and they are neophytes (70.71%), while 30.71% of alien flora shows invasive character. The majority of alien taxa have been intentionally introduced (73.57%) and have not been naturalized in the research area (52.86%). The largest number of taxa can be found in ruderal habitats and in the rural zone of the city. The highest levels of invasion can be seen in highly anthropogenic and humid habitats, with the largest number of invasive taxa appearing on the outskirts of the city. Analysis of flora shows that the composition of flora in Varaždin is more influenced by the type of habitat and the strength of anthropogenic influences than the level of urbanization