CONICET | Buscador de Institutos y Recursos Humanos

The influence of near-ambient and reducedsolar UV-B radiation on a peatland microfungal communitywas assessed by exposing experimental plots to UVselectivefiltration. Replicate plots were covered withspecial plastic films to effect treatments of near-ambientand attenuated solar UV-B. The microfungal communityfrom the top 1 cm of Sphagnum capitulum in a Tierra delFuego peatland was censused throughout three growingseasons, between 1999 and 2002. Sphagnum capitulaunder near-ambient UV-B were more compressed and heldmore water than capitula under reduced UV-B. This waterhad a greater conductivity and was more acidic under nearambientUV-B, as would be expected with increasedleaching from the Sphagnum leaves. Nine regularlyoccurring hyphal fungi from the peatland were identified,at least to genus. Over three field seasons, no treatmenteffect on total fungal colony abundance was recorded, butindividual species abundance was increased (Mortierellaalpina), decreased (Penicillium frequentans), or wasunaffected (P. thomii, Aureobasidium) by near-ambientUV-B. Species richness was also slightly lower undernear-ambient UV-B. These treatment differences weresmaller than seasonal or inter-annual fluctuations inabundance and species richness. In a growth chamberexperiment, lamp UV-B treatments indicated that realisticfluxes of UV-B can inhibit fungal growth in some species.In addition to this direct UV-B effect, we suggest thatchanges in the peatland fungal community under nearambientsolar UV-B may also result from increasednutrient and moisture availability in the Sphagnumcapitulum. The subtle nature of the responses of peatlandfungi to solar UV-B suggests that most fungal species weencountered are well adapted to current solar UV-B fluxes in Tierra del Fuego

enviar mensaje