The study aimed at an investigation of the vegetation of kettle-holes in the agricultural landscape of the Ziemia Chelminska region in northern central Poland. Most of these kettle-holes have been influenced strongly by human activities. 120 community types were described with regard to their species composition, structure, differentiation, synanthropization, ecological conditions and dynamics, as well as their affinities to similar plant communities from other regions in Europe. The significance of the kettle-holes as a natural resource is briefly discussed.

<p>Litteraturförteckning: s. [423]-434.</p>

ELVELAND, J. 1976. Coastal mires on the Storön peninsula, Norrbotten, N Sweden. Wahlenbergia 3. 274 pp. (map + 1 fig. in end pocket). Umeå.Vegetation, flora and habitat conditions of mires on and above the seashore have been studied in an eutrophic coastal area (Storön) in N Sweden. Here the rate of land uplift is almost 1 m per century and vegetational dynamics are rather intense in the younger mires, especially in the seashore fens recently "born from the sea" (primary mire formation).The mire vegetation is dealt with in three main groups: seashore fens, fens above the seashore and bog vegetation. The plant communities have been classified on a basis of their physiognomically dominant species. "Sphagnum fuscum islets" (often called "miniature raised bogs" or "miniature bogs") in the rich fens form the predominant type of bog vegetation. In the present paper the main emphasis has been laid on the rich fens above the seashore.Several vegetational gradients are dealt with, i. a. rich fen-poor fen, mire margin-mire expanse and the complex gradient mud-bottom/carpet/magnocaricetum/ lawn/hummock. Both small-scale and large-scale successions are discussed and a floristic list (vascular plants, bryophytes and lichens) with ecological annotations is presented.Extensive field measurements of pH and electrolytic conductivity of mire waters have been made. The pH, ash content, SÌO2r s r P#• C and N, total content and exchangeable fractions of Na, K, Mg, Ca, Mn and Fe have been determined at different depths for various kinds of peat. The chemistry of lagoon and lake sediments have also been studied. The vertical gradients shown by the chemical parameters are of special interest regarding the Sphagnum fuscum islets. The surface peats of the islets are "functionally ombrotrophic", while from a depth of ca. 30 cm and downwards the chemical characteristics are those of a rich fen peat.Historical and present-day mire utilization is discussed, especially hay-making and cattle grazing. / digitalisering@umu

<p>Summary in English</p>

<p>With an English summary</p>

Myrmarker har en stor roll i regleringen av den globala kolbalansen och koncentrationerna av koldioxid och metan i atmosfären, vilket gör dem till speciellt viktiga ekosystem ur ett klimatförandringsperspektiv. Förändringar av myrmarker genom naturlig utveckling eller antropogen påverkan kan därför få långtgående störningar av myrars klimatreglerande funktion. Mikroorganismer har en avgörande roll i biogeokemiska processer genom att t ex bryta ned organisk material i mark och därmed styra kolets kretslopp. För att förstå hur myrsystemen reagerar på störningar är det därför väsentligt att veta hur mikroorganismsamhällena reagerar genom förändringar i sammansättning och biogeokemisk aktivitet. Målet för studierna, som ligger till grund för denna avhandling, var att undersöka hur mikroorganismsamhällen i myrar reagerar på uppvärmning genom klimatförändring och ökade kväve- (N) och svavel- (S) halter i nederbörd. High through-put sekvensering användes för att studera taxonomiska och funktionella egenskaper hos mikroorganismerna i myrar och quantative PCR användes för att mer specifikt studera de metanbildande arkeorna. Två fältkampanjer vardera omfattande tre ombrotrofa myrar med olika klimatförhållanden och olika mängder N och S inederbörden användes för att undersöka lokala och storskaliga effekter på myrars mikrobiella samhällen. Resultaten visade att latudinell variation i geoklimatologiska förhållanden (temperatur ochnederbördsmängd) och deposition av näringsämnen hade en påverkan på sammansättningen av de mikrobiella samhällena och aktiva metanbildare förr än variationen i den kemiska miljön inom varje specifik myr. Myrväxtsamhällenas sammansättning för en specifik myr visades sig i stor utsträckning styra sammansättningen av motsvarande mikrobiella samhälle i torvprofilen. Detta framgick klart av i en analys av samexisterande nätverk av mikroorganismsamhällen och motsvarande växtsamhällen i en studie av tre geografiskt skilda myrar med olika kvävedeposition. Effekterna av klimatförändring och nederbörd med olika mängder av N och S studerades mer specifikt genom att analysera de mikrobiellasamhällena i  ett långliggande (18 år) försök. Påverkan av var och en av dessa manipulationer antingen förstärktes eller minskades, när de förekom i kombinationer. Ökad kvävedeposition var den faktor som hade starkast effekt. De långvariga störningarna medförde stora förändringar i den mikrobiella taxonomin inom samhällena. Detta återspeglades dock inte i den fysiologiska kapaciteten, vilket visar att det finns en stark buffring i myrarnas mikrobiella funktion. Detta tyder på att framtida utveckling av myrar i relation till olika störningar sannolikt inte kommer att påverka myrarnas roll för kolbalans och växthusgasutbyte med atmosfären. / Peatlands play a substantial role in regulating the global carbon balance and concentrations of the greenhouse gases CO2 and CH4 in the atmosphere, and are thus of utmost importance from a climate change perspective. Any changes of peatland functions due to natural or anthropogenic perturbations may result in changes in these ecosystem services. Soil microbial communities are essential drivers of biogeochemical processes, including the carbon cycle. In order to fully understand the effect of environmental perturbations on peatland functions, it is essential to understand how microbial communities are affected. The aim of the research presented in this thesis was to investigate the responses of the peat microbial communities to climate change and increased precipitation of nitrogen(N) and sulfur (S) compounds. High-throughput sequencing approaches were used to investigate the taxonomic and functional composition of microbial communities, and quantitative PCR was used to specifically target the methanogen community. Two field studies including three ombrotrophic peatlands each that differed in climatological conditions and atmospheric N and S depositions, were used to investigate and compare the effect of large- and local-scale environmental conditions on microbial communities. The results show that the variation in geo-climatological (temperature and precipitation) and atmospheric deposition conditions along the latitudinal gradient modulate the peat microbial community composition and the abundance of active methanogens to a greater extent thansite-related microhabitats. Furthermore, a tight coupling between the plant community composition of a site and the composition of its microbial community was observed, and was found to be mainly driven by plants rather than microorganisms. These co-occurrence networks are strongly affected by seasonal climate variability and the interactions between species in colder areas are more sensitive to climate change. The long-term effects of warming and increased N and S depositions on the peat microbial communities were further investigated using an 18-year in-situ peatland experiment simulating these perturbations. The impacts of each of these perturbations on the microbial community were found to either multiply or counteract one another, with enhanced N deposition being the most important factor. While the long-term perturbations resulted in a substantial shift in the taxonomic composition of microbial communities, only minor changes occurred in genome-encoded functional traits, indicating a functional redundancy. This could act as a buffer maintaining ecosystem functioning when challenged by multiple stressors, and could limit future changes in greenhouse gases and carbonexchange.