Browsing by Subject "rahkasammal"

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  • Pousi, Tomi (Helsingin yliopisto, 2017)
    In previous studies of Natural Resources Institute Finland it was noticed that Sphagnum moss had almost as good growing media properties as the white horticultural peat. In addition the Sphagnum moss based growing media prevented efficiently seed-borne Alternaria seedling blight and mosses were not molded with Peziza ostracoderma Korf that appears commonly on white horticultural peat. This thesis was part of the project of Natural Resources Institute entitled “Disease suppressive features of Sphagnum mosses”. The research aimed to survey the existence and applicability of fungistasis of Sphagnum moss as growing media. In the greenhouse experiments comparisons were made between mosses from six different sphagnum bog origins in their ability to suppress damping-off caused by Alternaria, Rhizoctonia and Pythium. Disease suppressive features of four sphagnum bogs mosses from three harvest depths were also determined. In the end of experiments the coverage by molds was determined and the fresh weights of seedlings were measured. In laboratory the amounts of common antagonist microbes in Sphagnum mosses were studied using different selective growth media. Results of different experiments were compared to white peat. In greenhouse experiments it was noticed that disease suppressive features varied a lot depending on the origin of the mosses and had different effects against different damp-ing-off pathogens. Mosses in the uppermost layers had best disease suppressive features against all three pathogens. The healthiest and biggest seedlings were obtained in growing media that contained mainly Sphagnum mosses and only a minimum amount of other peatland vegetation. There were only small amounts of molds on the top of Sphagnum moss growth media but also some phytotoxicity on seedlings was obtained Sphagnum mosses had only small amounts of antagonistic microbes as compared with peat. The results indicated that Sphagnum mosses have potential as growing medium that could efficiently prevent damping-off diseases and molds. However variation of disease suppressive was observed, which calls for more experiments to verify these effects. Minor amounts of antagonistic microbes detected in Sphagnum, as compared with white peat, suggests that disease suppressiveness may be caused by the phenolic compounds of Sphganum mosses.
  • Mäensivu, Anniina (Helsingfors universitet, 2017)
    Primary peat formation, infilling (terrestrialization) and paludification are the three main kinds of peatland formation processes. A peatland can develop over previously drier mineral soil if water table level rises or previously formed mire grows or expands. In Finland, the expansion of mires has been occasionally fast and in major part of ombrotrophic raised bogs it has occured while the mire has been in the minerotrophic fen stage. However, based on previous studies there have been different speculations whether the paludification still continues. Paludification study site at the edge of peatland and forested mineral soil was established in Häädetkeidas Strict Nature Reserve in year 1931. The study site, with a set of 4 transects, was studied in 1931, 1945, 1957 and 1997. Vegetation analysis on these permanent transects was repeated in 2016 as a part of this thesis. The aim of this study was to describe the variation of vegetation at the edge of the mire and forested mineral soil and study how the vegetation and plant species assemblies have changed between the years 1931–2016. A long-term vegetation study can reveal whether the species have changed from forest-dominated species to peatland-dominated species and does the paludification process still continue. The paludification process was studied by estimating the canopy-cover of ground layer and field layer vegetation and litter cover, measuring peat thickness, the thickness of aerated peat layer and anoxic peat layer and forest cover in four transects, consisting of 180 subplots. Non-metric multidimensional scaling (NMDS) was used to describe the data. Ground and field layer vegetation were examined by comparing the species’ average cover and frequencies. Environmental variables were studied by correlation analysis. Differences in peat thickness and in the coverage of Sphagnum-mosses between the examination years were studied with oneway variance analysis and t-test. In all four transects the coverage of Sphagnum-mosses had increased between the years 1931 and 2016. The coverage of forest mosses had decreased in two out of four transects. Succession related changes in species were observed in both vegetation layers. There was variation in the vegetation development between the transects and they seemed to be in different stages of the succession and paludification processes. In 93 percent of the study plots the thickness of peat layer had increased during the last 19 years. The changes in vegetation between the years 1931 and 2016 as well as the growth of the peat layer suggests that the paludification process still continues.
  • Punkka, Eetu (Helsingin yliopisto, 2019)
    Substrate producers are interested in new climate-friendly alternatives due to the problematic nature of the peat life cycle and the uncertain status. The Sphagnum moss has good properties for substrate production and, due to its productivity, is a potential alternative to peat harvesting. Indeed, the Sphagnum moss has been harvested for this purpose for several years. Exploitation of the new natural resource involves many issues to take care of in order to consider sustainable use. One of these is the impact on climate. Of the greenhouse gases, carbon dioxide and me-thane play a role in the climate emissions of ombrotrophic mires. Nitrous oxide is not considered here. In the case of carbon dioxide, it is important to study the carbon stocks of the decaying material and, in the case of methane, vege-tation restoration and plant species relationships are considered carefully. The aim of this Master's thesis was to study observations on the climatic effects of Sphagnum harvesting for possi-ble further research. Climate effects were compared with untreated reference areas and, in addition, the differences in emissions between peatland types were provisionally investigated. The climatic effects of Sphagnum harvesting were also compared with the corresponding figures of horticultural peat. Carbon dioxide was studied by the carbon content of drilled peat samples. The climate impact of the peat that wasn’t formed as a result of the harvesting was also taken into account in the calculations. Methane emissions were examined on the basis of restoration of cover from vegetation analysis and plant species relationship data. The Sphagnum harvesting areas were also examined about general information of the harvesting area for example harvesting marks in the ground, tree stand and ditch conditions. Field work was carried out in summer 2019 in Kihniö area on 12 bogs. In general, the vegetation of the harvesting areas was characterized by a strong pioneer effect on Eriophorum vagi-natum. The most recent harvesting areas were still nearly plant-free, but at the time of the study, the harvesting areas that had recovered three growing seasons had already begun to clearly recover in terms of vegetation. Within 10 years, the vegetation had completely recovered. In relative terms, the proportion of Eriophorum vaginatum in the oldest areas was clearly higher than in the reference areas and the regenerated vegetation in the harvesting areas was poorer than in the reference areas. However, the presence of Eriophorum vaginatum also seems to contribute to the spread of Sphagnum sp. In addition, the harvesting marks of the harvesting seems to be important above all for the recovery of Sphagnum sp. The flat surface facilitates recovery, but also the unharvested spots within the harvesting areas. Based on the greenhouse gas calculations, the emission of the Sphagnum harvesting area was 10.26 kg/m2 CO2 in 13 years. Comparing the differences between the different bog types, it was found that the harvesting is more climate friendly in Sphagnum-bogs than in cottongrass-bogs. The Sphagnum harvesting is clearly a better alternative to harvesting peat from a climate point of view, when emissions are distributed on the dry masses of the growing media produced. When reducing climate emissions, the major part of total emissions is generated by the specific decontaminated substrate. The importance of the vegetation is less significant in the overall result. In this study, the climate effects of the Sphagnum harvesting were tentatively mapped, as the topic has not been studied previously in Finnish conditions. More research is needed with wider sampling and long-term follow-up.
  • Lehto, Anniina (Helsingin yliopisto, 2019)
    Peat is currently the most important raw material for growing media in horticulture. For a while now, alternative raw materials have been tested since there is a demand for more sustainable substrates for horticultural production. The aim of this research was to determine the effects of different Sphagnum L. biomass containing growing media on the vegetative and generative growth on Pelargonium L´Hér and Begonia L., and to determine how the different growing media affect the longevity of the plant in water deficit. There were two types of Sphagnum biomass used for the study and there were eight different compositions of Sphagnum based growing media in total. The growing media consisted of varying amounts of Sphagnum fibre and peat. Peat was amended with either 100%, 75%, 25% or 0% of Sphagnum fibre. 47 days from the beginning of the experiment some of the Begonias and Pelargoniums were transferred to a water deficit treatment in national plant phenotyping infrastructure (NaPPI) for non-destructive imaging. The results showed that the Pelargoniums cultivated in Sphagnum-based growing media had higher fresh and dry weights than the ones cultivated in 100% peat. With Begonia, there were no differences in fresh or dry weights of the plants between the treatments. The leaf areas were in trend with the fresh and dry weights. The higher the fresh and dry weights, the higher was the leaf area. There were no differences in the onset of flowering or the number of flowers in the plants between the different growing media for Pelargonium or Begonia. There were no notable morphological differences in the plants between the treatments either, which indicates that the Sphagnum fibre did not affect the ornamental value of Pelargonium and Begonia. In the water deficit treatment, there were no differences between the growing media in any of the values measured. The results indicate that the vegetative and generative growth of Pelargonium and Begonia on Sphagnum-based growing media was on acceptable level for production. Considering these results, Sphagnum biomass could be used in the growing media to replace peat, either partially or completely, for at least certain ornamentals.