Obnova združb pajkov v vzhodni Ukrajini po spontanem poletnem požaru v stepi, kjer prevladujejo šopaste trave

Recently, anthropogenic fires in protected areas have become more frequent. I studied the response of the spider community after an extensive summer fire in the ‘Striltsivskyi Steppe’ Reserve in eastern Ukraine. A total of 117 spider species was found in the pre-fire period, 40 species were registered in the first and 89 species in the third post-fire year. Herb-dwelling spiders began to colonize burnt plots in July, when juveniles of the new generation began dispersing. In September, their abundance was similar to that of undisturbed steppe and within three years, the spider assemblages recovered almost completely. Cursorial ground-dwellers in the first post-fire year decreased in species richness and increased in activity density. In the third year, their species diversity and activity density became much higher than in control plots. Some xerophilous species benefited from the fire. Litter dwellers are extremely vulnerable. During the three post-fire years, their numbers and diversity did not recover. Some rare species with a patchy geographical distribution disappeared from the local fauna. Such a reaction of endangered species is the main restriction on the use of fire as a conservation management. The prerequisite for its implementation is maintaining relevant refuges for threatened species.Antropogeni požari na zavarovanih območjih so v zadnjem času vse bolj pogosti. Proučevala sem odziv združbe pajkov po ekstenzivnem poletnem požaru v rezervatu ‘Striltsivskyi Steppe’ v vzhodni Ukrajini. V obdobju pred požarom sem našla 117 vrst pajkov, 40 vrst je bilo zabeleženih v prvem letu, 89 vrst pa v tretjem letu po požaru. Pajki, ki prebivajo na zeliščih, so začeli naseljevati požgane ploskve julija, ko so se začeli razširjati juvenilni osebki nove generacije. Septembra je bila njihova abundanca podobna kot v nemoteni stepi in po treh letih se je vrstna sestava pajkov popolnoma obnovila. Vrstna pestrost pajkov, ki prebivajo na tleh, se je v prvem letu po požaru zmanjšala, povečala pa se je njihova aktivna gostota. V tretjem letu sta bili vrstna pestrost in aktivna gostota višji kot na kontrolnih ploskvah. Nekatere kserofilne vrste so imele zaradi požara prednost. Vrste, ki jih najdemo v opadu, so izredno ranljive. Njihovo število in pestrost se v treh letih po požaru nista obnovila. Nekatere redke vrste z zaplatasto geografsko razširjenostjo, so izginile s tega območja. Odziv redkih vrst je glavna omejitev za uporabo ognja za naravovarstven način gospodarjenja. Predpogoj za njegovo uporabo je vzpostavitev ustreznih zatočišč (refugijev) za ogrožene vrste