LITTER DECOMPOSITION IN SOILS OF OVERGROWN GRASSLANDS IN DEPENDANCE OF TEMPERATURE | Temperaturna odvisnost razgradnje opada v tleh travnikov v zaraščanju

English. The aim of the study was to examine whether the effect of projected temperature rises due to the global climate change could accelerate plant litter decomposition in soils of overgrown grasslands. The experiment was carried out under natural conditions at the locations of Bohinj-Polje and Uskovnica with similar environmental conditions (precipitation, parent material and soil development, plant communities) and the difference in air temperatures. The average difference in monthly air temperatures during our study were higher in Bohinj for 4.4 °C (± 1.5 °C) than in Uskovnica. Nylon mesh bags with mixed plant litter from both locations were placed into the Of horizon of the soil profiles at both locations in autumn 2007. The litter bags were sampled successively at 4 sampling times until May 2009 in 5 replicates. The litter degradation, expressed as mass loss, was throughout our study 57.1 ± 1.2 % (0 - 526 days) in Bohinj, 57.3 ± 2.6 % (0 - 555 days) at Uskovnica. No statistically significant differences in litter decomposition rate and seasonal pattern of mass loss was found between the sites. The dynamics of the total content of cellulose and lignin, Corg and N and their soluble forms (DOC and DON) were similar between the sites as well. The lignin content in the plant material did not statistically significantly change during the experiment. The results of our experiment did not confirm the effect of the difference in average air temperature on decomposition rate decreases. The results did not confirm any effect from the difference in the average monthly air temperature between the sites on the plant litter decomposition in our study.

Slovenian. Namen raziskave je bil ugotoviti, ali lahko dvig temperature, ki je predviden v projekcijah podnebnih sprememb, pospeši razgradnjo opada v tleh travnikov v zaraščanju. Poskus smo izvedli v naravnih razmerah na lokacijah Bohinj-Polje in Uskovnica s podobnimi okoljskimi razmerami (padavine, matična podlaga in razvoj tal, rastlinske združbe), ter razliko v temperaturah zraka. Povprečne mesečne temperature med poskusom so bile v Bohinju za 4,4 °C (± 1,5 °C) višje kot na Uskovnici. Jeseni 2007 smo na obeh lokacijah v Of horizont talnega profila vstavili mrežaste najlonske vrečke, v katerih je bila mešanica rastlinskega opada z obeh lokacij. Vrečke z opadom smo vzorčili zaporedno v 4 terminih do maja 2009 v 5 ponovitvah. Razgradnja opada, izražena z izgubo mase, je bila v celotnem obdobju raziskave 57,1 ±1,2 % (0 - 526 dni) v Bohinju oz. 57,3 ±2,6 % (0 - 555 dni) na Uskovnici. Med lokacijama nismo ugotovili statistično značilnih razlik v hitrosti razgradnje opada in sezonskem vzorcu zmanjševanja mase. Dinamika skupne vsebnosti celuloze in lignina, Corg in N ter njunih topnih oblik (DOC in DON) je bila med lokacijama prav tako podobna. Vsebnost lignina v rastlinskem opadu se v času našega poskusa ni statistično značilno spreminjala. Rezultati poskusa niso potrdili vpliva razlike v povprečni mesečni temperaturi zraka med lokacijama na hitrost razgradnje opada.