Detection of cellulolytic activity of bacteria and fungi growing on agar surfaces

Summary Cellulolytic activity of four fungal species growing on solid medium containing acid-swollen cellulose could be detected much more easily if fungal growth was partly inhibited by the detergent Triton X-100. The dye, aniline blue-black, did not affect growth but increased the sensitivity of detection of cellulolytic activity of both fungi and bacteria. Separating fungi from cellulose fibres by a layer of agar or by filters showed that cell-fibre contact is not necessary for cellulose degradation. Such degradation is clearer when contact is prevented.     

Response of calcareous grassland vegetation to mowing and fluctuating weather conditions

Question: What determines the balance between the cover values of vascular plants, lichens and mosses in dry calcareous grassland communities? Location: Western Estonia. Methods: A five‐year (2001–2005) study was conducted in a dry calcareous grassland. The cover of mosses, lichens and vascular plants and all moss species was recorded in permanent plots. Vascular plants were cut in half of the plots. Data from a nearby weather station were used to calculate mean values of different weather parameters and a summer moisture index for the study years. Results: Significant differences in cover values between years were found. The fluctuations of total moss cover and the cover of the dominating moss species Ctenidium molluscum followed changes in annual precipitation. Both cover values were highest in years with high precipitation. The cover change of vascular plants was best characterized by the moisture index of the growth period (three summer months). Summers with high moisture indexes facilitated vascular plant and lichen growth. Annual precipitation and the cover of mosses had a negative influence on the cover of vascular plants. The cutting of vascular plants did not have a significant effect on moss and lichen cover. Conclusions: 1. On dry calcareous grasslands the growth of mosses is enhanced by high annual precipitation, while the growth of vascular plants and lichens is influenced rather by the high summer moisture index. The cover of vascular plants is inhibited by the large moss cover. 2. Mowing of vascular plants does not influence the cover of mosses and lichens.     

Recent patterns of sediment accumulation in a small closed eutrophic lake revealed by the sediment records

A short-core palaeolimnological investigation was undertaken with the aim ofacquiring knowledge of sediment deposition. Analyses of the lithological composition of sediments from the whole-lake basin were performed on the small eutrophic L. Linajärv (northern Estonia) and the concentrations of mineral and organic matter were measured on 647 sub-samples from 14 sediment cores. The accumulation rate of the sediment sequences was established and C/N ratios of organic matter in some cores were recorded. Results indicate that the water depth, basin slopes and distance to the shore have the most important impact on the physical sediment properties. It was shown that variations in the mineral matter concentrations were influenced by the changes in deposition conditions in the areas with steep slopes. The study indicated that more objective information about the sedimentation mechanisms is obtained using analysis of the concentration ratio of mineral and organic matter since it reduces the implied role of diagenetic compaction.