Browsing by Subject "Sphagnum"

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  • Korrensalo, Aino; Kettunen, Laura; Laiho, Raija; Alekseychik, Pavel; Vesala, Timo; Mammarella, Ivan; Tuittila, Eeva-Stiina (2018)
    Question: Peatlands are globally important for carbon storage due to the imbalance between plant biomass production and decomposition. Distribution of both live standing biomass (BM, dry mass g/m(2)) and biomass production (BMP, dry mass gm(-2) growing season(-1)) are known to be dependent on the water table (WT). However, the relations of BM and BMP to WT variation are poorly known. Here we investigated, how the above- and below-ground BM and BMP of three different plant functional types (PFTs), dwarf shrubs, sedges and Sphagnum mosses, relate to natural WT variation within an ombrotrophic boreal bog. In addition, we estimated ecosystem-level BMP and compared that with ecosystem net primary production (NPP) derived from eddy covariance (EC) measurements. Location: Siikaneva bog, Ruovesi, Finland. Methods: We quantified above- and below-ground BM and BMP of PFTs along the WT gradient, divided into six plant community types. Plant community scale BM and BMP were up-scaled to the ecosystem level. NPP was derived from EC measurements using a literature-based ratio of heterotrophic respiration to total ecosystem respiration. Results: BM varied from 211 to 979 g/m(2) among the plant community types, decreasing gradually from dry to wet community types. In contrast, BMP was similar between plant community types (162-216 g/m(2)), except on nearly vegetation-free bare peat surfaces where it was low (38 g/m(2)). Vascular plant BM turnover rate (BMP:BM, per year) varied from 0.14 to 0.30 among the plant community types, being highest in sedge-dominated hollows. On average 56% of the vascular BM was produced below ground. Mosses, when present, produced on average 31% of the total BM, ranging from 16% to 53% depending on community type. EC-derived NPP was higher than measured BMP due to underestimation of certain components. Conclusions: We found that the diversity of PFTs decreases the spatial variability in productivity of a boreal bog ecosystem. The observed even distribution of BMP resulted from different WT optima and BMP:BM of dwarf shrubs, sedges and Sphagnum species. These differences in biomass turnover rate and species responses to environmental conditions may provide a resilience mechanism for bog ecosystems in changing conditions.
  • Kastovska, Eva; Strakova, Petra; Edwards, Keith; Urbanova, Zuzana; Barta, Jiri; Mastny, Jiri; Santruckova, Hana; Picek, Tomas (2018)
    Peatlands are large repositories of carbon (C). Sphagnum mosses play a key role in C sequestration, whereas the presence of vascular plants is generally thought to stimulate peat decomposition. Recent studies stress the importance of plant species for peat quality and soil microbial activity. Thus, learning about specific plant-microbe-soil relations and their potential feedbacks for C and nutrient cycling are important for a correct understanding of C sequestration in peatlands and its potential shift associated with vegetation change. We studied how the long-term presence of blueberry and cotton-grass, the main vascular dominants of spruce swamp forests, is reflected in the peat characteristics, soil microbial biomass and activities, and the possible implications of their spread for nutrient cycling and C storage in these systems. We showed that the potential effect of vascular plants on ecosystem functioning is species specific and need not necessarily result in increased organic matter decomposition. Although the presence of blueberry enhanced phosphorus availability, soil microbial biomass and the activities of C-acquiring enzymes, cotton-grass strongly depleted phosphorus and nitrogen from the peat. The harsh conditions and prevailing anoxia retarded the decomposition of cotton-grass litter and caused no significant enhancement in microbial biomass and exoenzymatic activity. Therefore, the spread of blueberry in peatlands may stimulate organic matter decomposition and negatively affect the C sequestration process, whereas the potential spread of cotton-grass would not likely change the functioning of peatlands as C sinks.
  • Laine, Anna M.; Lindholm, Tapio; Nilsson, Mats; Kutznetsov, Oleg; Jassey, Vincent E. J.; Tuittila, Eeva-Stiina (John Wiley & Sons Ltd, 2021)
    Journal of Ecology 109, 4 (2021), 1774–1789
    1. Most of the carbon accumulated into peatlands is derived from Sphagnum mosses. During peatland development, the relative share of vascular plants and Sphagnum mosses in the plant community changes, which impacts ecosystem functions. Little is known on the successional development of functional plant traits or functional diversity in peatlands, although this could be a key for understanding the mechanisms behind peatland resistance to climate change. Here we aim to assess how functionality of successive plant communities change along the autogenic peatland development and the associated environmental gradients, namely peat thickness and pH, and to determine whether trait trade-offs during peatland succession are analogous between vascular plant and moss communities. 2. We collected plant community and trait data on successional peatland gradients from post-glacial rebound areas in coastal Finland, Sweden and Russia, altogether from 47 peatlands. This allowed us to analyse the changes in community-weighted mean trait values and functional diversity (diversity of traits) during peatland development. 3. Our results show comparative trait trade-offs from acquisitive species to conservative species in both vascular plant and Sphagnum moss communities during peatland development. However, mosses had higher resistance to environmental change than vascular plant communities. This was seen in the larger proportion of intraspecific trait variation than species turnover in moss traits, while the proportions were opposite for vascular plants. Similarly, the functional diversity of Sphagnum communities increased during the peatland development, while the opposite occurred for vascular plants. Most of the measured traits showed a phylogenetic signal. More so, the species common to old successional stages, namely Ericacae and Sphagna from subgroup Acutifolia were detected as most similar to their phylogenetic neighbours. 4. Synthesis. During peatland development, vegetation succession leads to the dominance of conservative plant species accustomed to high stress. At the same time, the autogenic succession and ecological engineering of Sphagna leads to higher functional diversity and intraspecific variability, which together indicate higher resistance towards environmental perturbations.
  • Kiheri, Heikki; Velmala, Sannakajsa; Pennanen, Taina; Timonen, Sari; Sietiö, Outi-Maaria; Fritze, Hannu; Heinonsalo, Jussi; van Dijk, Netty; Dise, Nancy; Larmola, Tuula (2020)
    Northern peatlands are often dominated by ericaceous shrub species which rely on ericoid mycorrhizal fungi (ERM) for access to organic sources of nutrients, such as nitrogen (N) and phosphorus (P), and host abundant dark septate endophytes (DSE). Relationships between hosts and fungal symbionts may change during deposition of anthropogenic N and P. We studied the long-term effects of N and P addition on two ericaceous shrubs, Calluna vulgaris and Erica tetralix, at Whim Bog, Scotland by analyzing fungal colonization of roots, enzymatic activity, and fungal species composition. Unexpectedly, the frequency of typical ERM intracellular colonization did not change while the occurrence of ERM hyphae tended to increase and DSE hyphae to decrease. Our findings indicate that altered nutrient limitations shift root associated fungal colonization patterns as well as affecting ericaceous root enzyme activity and thereby decomposition potential. Reduction of recalcitrant fungal biomass in melanized DSE may have implications for peatland C sequestration under nutrient addition.
  • Manninen, Sirkku; Kivimäki, S.; Leith, I. D.; Leeson, S. R.; Sheppard, L. J. (2016)
    Long-term additions of nitrogen (N) to peatlands have altered bryophyte growth, species dominance, N content in peat and peat water, and often resulted in enhanced Sphagnum decomposition rate. However, these results have mainly been derived from experiments in which N was applied as ammonium nitrate (NH4NO3), neglecting the fact that in polluted areas, wet deposition may be dominated either by NO3- or NH4+. We studied effects of elevated wet deposition of NO3- vs. NH4+ alone (8 or 56 kg N ha(-1) yr(-1) over and above the background of 8 kg N ha(-1) yr(-1) for 5 to 11 years) or combined with phosphorus (P) and potassium (K) on Sphagnum quality for decomposers, mass loss, and associated changes in hummock pore water in an ombrotrophic bog (Whim). Adding N, especially as NH4+, increased N concentration in Sphagnum, but did not enhance mass loss from Sphagnum. Mass loss seemed to depend mainly on moss species and climatic factors. Only high applications of N affected hummock pore water chemistry, which varied considerably over time. Overall, C and N cycling in this N treated bog appeared to be decoupled. We conclude that moss species, seasonal and annual variation in climatic factors, direct negative effects of N (NH4+ toxicity) on Sphagnum production, and indirect effects (increase in pH and changes in plant species dominance under elevated NO3- alone and with PK) drive Sphagnum decomposition and hummock C and N dynamics at Whim. (C) 2016 Elsevier B.V. All rights reserved.
  • Kangas, Laura (Helsingfors universitet, 2013)
    Forested wetlands throughout the world are valuable habitats; especially in relatively species-poor northern regions, they can be considered biological hotspots. Unfortunately, these areas have been degraded and destroyed. In recent years, however, the biological importance of wetlands has been increasingly recognized, resulting in the desire to restore disturbed habitats or create in place of destroyed ones. Restoration work is taking place across the globe in a diversity of wetland types, and research must be conducted to determine successful techniques. As a result, two studies of the effects of wetland restoration and creation were conducted in forested wetlands in northern Michigan and southern Finland. In North America, northern white-cedar wetlands have been declining in area, despite attempts to regenerate them. Improved methods for successfully establishing northern white-cedar are needed; as a result, the target of the first study was to determine if creating microtopography could be beneficial for white-cedar recruitment and growth. In northern Europe, spruce swamp forests have become a threatened ecosystem due to extensive drainage for forestry. As part of the restoration of these habitats, i.e. rewetting through ditch blocking, Sphagnum mosses are considered to be a critical element to re-establish, and an in-depth analysis of how Sphagnum is responding to restoration in spruce swamp forests has not been previously done. As a result, the aim of the second study was to investigate the ecophysiological functioning of Sphagnum and feather mosses across a gradient of pristine, drained, and restored boreal spruce swamp forests.
  • Braithwaite, R. (David Bogue, 1880)
  • 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.
  • Korrensalo, Aino; Mehtätalo, Lauri; Alekseychik, Pavel; Uljas, Salli; Mammarella, Ivan; Vesala, Timo; Tuittila, Eeva-Stiina (2020)
    We quantified the role of spatially varying vegetation composition in seasonal and interannual changes in a boreal bog’s CO2 uptake. We divided the spatially heterogeneous site into six microform classes based on plant species composition and measured their net ecosystem exchange (NEE) using chamber method over the growing seasons in 2012–2014. A nonlinear mixed-effects model was applied to assess how the contributions of microforms with different vegetation change temporally, and to upscale NEE to the ecosystem level to be compared with eddy covariance (EC) measurements. Both ecosystem respiration (R) and gross photosynthesis (PG) were the largest in high hummocks, 894–964 (R) and 969–1132 (PG) g CO2 m−2 growing season−1, and decreased toward the wetter microforms. NEE had a different spatial pattern than R and PG; the highest cumulative seasonal CO2 sink was found in lawns in all years (165–353 g CO2 m−2). Microforms with similar wetness but distinct vegetation had different NEE, highlighting the importance of vegetation composition in regulating CO2 sink. Chamber-based ecosystem-level NEE was smaller and varied less interannually than the EC-derived estimate, indicating a need for further research on the error sources of both methods. Lawns contributed more to ecosystem-level NEE (55–78%) than their areal cover within the site (21.5%). In spring and autumn, lawns had the highest NEE, whereas in midsummer differences among microforms were small. The contributions of all microforms to the ecosystem-level NEE varied seasonally and interannually, suggesting that spatially heterogeneous vegetation composition could make bog CO2 uptake temporally more stable.