Decomposition of labile and recalcitrant coniferous litter fractions affected by temperature during the growing season

Temperate coniferous forest soils are considered important sinks of soil organic carbon(C).Fresh C inputs may,however,affect soil microbial activity,leading to increased organic matter decomposition and carbon dioxide production.Litter consists of labile and recalcitrant fractions which are thought to be utilized by distinct microbial communities and at different rates during the growing season.In this study,we incubated the whole litter(LC+RC),the labile(LC)and the recalcitrant(RC)fractions with the coniferous soil at two temperatures representing spring/autumn(10℃)and summer(20℃)for one month.Soil respiration and microbial community composition were regularly determined using phospholipid fatty acids as biomarkers.The LC fraction greatly increased soil respiration at the beginning of the incubation period but this effect was rather short-term.The effect of the RC fraction persisted longer and,together with the LC+RC fraction,respiration increased during the whole incubation period.Decomposition of the RC fraction was more strongly affected by higher temperatures than decomposition of the more labile fractions(LC and LC+RC).However,when we consider the relative increase in soil respiration compared to the dH2 O treatment,respiration increased more at a lower temperature,suggesting that available C is more important for microbial metabolism at lower temperatures.Although C was added only once in our study,no changes in microbial community composition were detected,possibly because the microbial community is adapted to relatively low amounts of additional C such as the amounts naturally found in litter.

Roles of species-preferential seed dispersal by ants and endozoochory in Melampyrum(Orobanchaceae)

Aims Melampyrum pratense and M.subalpinum are two myrmeco-chorous species,which possess similar habitat requirements and frequently occur together.Despite this,their population sizes differ markedly.Melampyrum pratense populations are usually very large,whereas M.subalpinum has rather small and isolated populations.We suggest that such an imbalance might be partially influenced by the difference in ant-mediated seed-removal rates.genus Melampyrum is considered to be exclusively myrme-cochorous,though to achieve the recent distribution of some Melampyrum species during the Holocene myrmecochory would be highly insufficient.We suggest that endozoochory takes place in the long-distance migration,whereas myrmecochory is important for the removal of seeds on a local scale.Methods For seed-preference analysis,M.pratense and M.subalpinum mixed seed samples were placed around Formica polyctena anthills.after a period of time,the remaining seeds of both species were counted for each sample.The results were analysed by analysis of variance and generalized linear mixed-effect model.To test myrmecochorous removal distances,M.pratense seeds were covered with fluorescent dactyloscopic powder and placed in the vicinity of a large ant trail.The area around the starting plot was searched in the dark using uV lED torchlight 7 h after the beginning.The distance from the starting plot was measured for each seed found.birds,rodents,leporine and a ruminant were fed with M.pratense seeds and fresh plants to test the possibility of endozoochorous dispersal of the species.animal droppings were searched for intact seeds.Important Findingsour field studies show that from mixed seed samples,containing both species,ants significantly preferred the seeds of M.pratense.This may be one of factors that has positive influence on M.prat-ense success in seed dispersal on mixed stands and consequently in the colonization of favourable sites.Experiments focusing on ant-mediated dispersal distance revealed that F.polyctena ants are able to move seeds over a distance of 36 m in only 7 h.This distance is among the furthest known myrmecochorous removals of forest plant seeds.a new Melampyrum seed disperser Oligolophus tridens(opiliones)was observed repeatedly.our pilot study documented that Melampyrum seeds are able to pass through the digestive tract of a cow intact.This suggests that large ruminants such as deer,bison or forest-grazing livestock may function as important long-distance dispersers of Melampyrum species.