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  • 1.
    Berg, Björn
    et al.
    Dipartimento biologia strutturale e funzionale, Complesso universitario di Monte S. Angelo, Napoli, Italy; Department of forest ecology, University of Helsinki, Helsinki, Finland.
    Davey, M. P.
    Department of plant sciences, University of Cambridge, Cambridge, United Kingdom.
    De Marco, A.
    Dipartimento biologia strutturale e funzionale, Complesso universitario di Monte S. Angelo, Napoli, Italy.
    Emmett, B
    Centre for ecology and hydrology, Bangor.
    Faituri, M.
    Department of soils and water, Omar AlMukhtar university, Elbeida, Libyan Arab Jamahiriya.
    Hobbie, S. E.
    Department of ecology, evolution and behavior, University of Minnesota, St. Paul, USA.
    Johansson, Maj-Britt
    University of Gävle.
    Liu, C.
    Department of landscape science and engineering, College of agriculture and biology, Shanghai, ChinaShanghai Jiao Tong university,.
    McClaugherty, C.
    Department of biology, Mount Union college, Alliance, USA.
    Norell, L.
    Unit of applied statistics and mathematics, SLU, Uppsala, Sweden.
    Rutigliano, F. A.
    Dipartimento di scienze ambientali, Seconda Università degli studi di Napoli, Caserta, Italy.
    Vesterdal, L.
    Forest & landscape Denmark, University of Copenhagen, Hørsholm, Denmark.
    Virzo De Santo, A.
    Dipartimento biologia strutturale e funzionale, Complesso universitario de Monte S. Angelo, Napoli, Italy.
    Factors influencing limit values for pine needle litter decomposition: A synthesis for boreal and temperate pine forest systems2010In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 100, no 1, p. 57-73Article in journal (Refereed)
    Abstract [en]

    We synthesized available data for decomposition of pine (Pinus) needle litter in pine forests to determine the litter chemical characteristics and climate factors that explained variation in the limit value, i. e. the level of accumulated mass loss at which the decomposition process either continues at a very low rate or possibly stops. Our data base included 56 separate studies on decomposition of pine needle litter, spanning Scots pine, lodgepole pine, Aleppo pine, stone pine and white pine, mainly incubated at the site of collection. Studies had 5 to 19 samplings, on average 10, and the decomposition was followed to a mass loss ranging from 47 to 83%, on average 67%. The periods from 3.0 to 5.4 years, on average 3.9 years, were of sufficient duration to allow estimates of limit values of decomposition. We used a linear mixed model with regression effects to relate limit values to potential explanatory variables, namely the sites' long-term mean annual temperature (MAT) and mean annual precipitation (MAP) and to substrate-chemistry factors. Regarding the latter, we explored two models; one that included initial concentrations of water solubles, lignin, N, P, K, Ca, Mg, and Mn and one that included only lignin, N, Ca, and Mn to focus on those nutrients known to influence lignin degradation. Using backward elimination significant explanatory variables were determined. For litter decomposed in its site of origin we found the limit value to depend mainly on the initial concentration of Mn, with higher Mn concentrations resulting in higher accumulated mass loss. Thus, litter with higher Mn reached a higher limit value and left a smaller stable fraction. This is likely due to the fact that Mn is an essential component of ligninolytic enzymes important for degrading litter in the later stages of decomposition. Manganese has received little attention in decomposition studies to date. Given its significance in this synthesis, the role of Mn in influencing variation in the late stages of decomposition among ecosystems and among litters of other genera besides Pinus deserves further attention.

  • 2.
    Berg, Björn
    et al.
    Department of Forest Sciences, University of Helsinki, Helsinki, Finland .
    Erhagen, Björn
    Department of Ecology and Environmental Sciences, University of Umeå, Umeå, Sweden .
    Johansson, Maj-Britt
    University of Gävle.
    Nilsson, Mats
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå.
    Stendahl, Johan
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala.
    Trum, Florence
    Earth and Life Institute, Universite' catolique de Louvain, Louvain-la-Neuve, Belgium .
    Vesterdal, Lars
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Fredriksberg C, Denmark .
    Manganese in the litter fall-forest floor continuum of boreal and temperate pine and spruce forest ecosystems: a review2015In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 358, p. 248-260, article id 15021Article, review/survey (Refereed)
    Abstract [en]

    We have reviewed the literature on the role of manganese (Mn) in the litter fall-to-humus subsystem. Available data gives a focus on North European coniferous forests. Manganese concentrations in pine (Pinus spp.) foliar litter are highly variable both spatially and temporally within the same litter species and for the genus Pinus we found a range from 0.03 to 3.7mgg-1. Concentrations were related negatively to site mean annual temperature (MAT) and annual actual evapotranspiration (AET) for pine species litter but not for that of Norway spruce (Picea abies) as a single species. Combined data for several species showed a highly significant relationship to MAT.Manganese peroxidase is an Mn-dependent enzyme, found in white-rot fungi, essential for the degradation of lignin and ligninlike compounds. The decomposition rates of lignified litter tissue (late phase) is positively related to the litter’s Mn concentration. Further, the Mn concentration is positively related to the limit value for decomposition - the higher the Mn concentration the smaller the stable litter fraction. Manganese release from decomposing litter appears at least in part to be species related. Thus was release from pine needle litter significantly faster (p<. 0.001) than that from the Mn-richer litter of Norway spruce. Over Northern Europe concentrations of total Mn in mor humus as well as extractable Mn in the mineral soil increase with decreasing MAT and over a climatic gradient the Mn concentrations in Norway spruce mor increase more with decreasing MAT than in a gradient with Scots pine. Higher Mn concentrations in humus appear to decrease its stability and result in a higher release of carbon dioxide (CO<inf>2</inf>) and dissolved organic carbon (DOC). We conclude that this may explain (i) the lower amount of carbon (C) in mor layers under Norway spruce as compared to Scots pine as well as the higher amount of C in mineral soil under spruce. The increase in nitrogen (N) concentration in humus, following N fertilization resulted in a decrease in that of Mn. We have found four cases - empirical - with negative interaction between Mn and N; (i) in pine foliar litter fall concentrations of Mn decrease with site MAT whereas those of N increase, (ii) in decomposing late-stage litter with N retarding and Mn stimulating decomposition, (iii) for the stable phase, limit values are related negatively to N and positively to Mn, and (iv) Mn concentrations in humus decrease with MAT whereas those of N increase.

  • 3.
    Berg, Björn
    et al.
    University of Helsinki, Helsinki, Finland.
    Erhagen, Björn
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Johansson, Maj-Britt
    University of Gävle.
    Vesterdal, Lars
    University of Copenhagen, Denmark.
    Faituri, Mikaeel
    Omar AlMuktar University, Elbeida, Libya.
    Sanborn, Paul
    University of British Columbia, Prince George, Canada.
    Nilsson, Mats
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Manganese dynamics in decomposing needle and leaf litter: a synthesis2013In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 43, no 12, p. 1127-1136Article in journal (Refereed)
    Abstract [en]

    The aim of the present synthesis paper was to determine whether concentration changes and net release of manganese (Mn), as related to accumulated litter mass loss, are related to initial Mn concentration, mean annual temperature (MAT), mean annual precipitation (MAP), and tree genus or species. We also examined whether limit values for decomposition are related to initial litter Mn concentration, MAT, and MAP. We compiled 84 foliar litter decomposition studies, conducted mainly in boreal and temperate forest ecosystems, for which Mn dynamics had been well documented. Manganese concentration and amount were related to accumulated litter mass loss at each sampling time for each single study, as well as for (i) all studies combined (n = 748) and (ii) for species groups viz. Norway spruce (Picea abies (L.) Karst.) (n = 284), pine (Pinus) species (n = 330), and deciduous species (n = 214). The changes in Mn concentration with accumulated mass loss followed quadratic functions showing significantly higher Mn concentrations for Norway spruce vs. Scots pine (Pinus sylvestris L.) (p < 0.0001) and vs. deciduous species (p < 0.01), as well as significantly higher for deciduous species vs. Scots pine (p < 0.0001). Manganese release rates were different among the three species groups (p < 0.001). Still, rates were related to initial Mn concentrations (p < 0.001) for all litter types combined and for the three species groups. Norway spruce released Mn more slowly than pine and deciduous species. Rates were related to climatic factors for litter of Norway spruce and deciduous species. Limit values for all litter and for pine species separately were related to Mn (p < 0.001) and MAT (p < 0.001). For Norway spruce, limit values were related to MAT (p < 0.001) and MAP (p < 0.01). It appears that Norway spruce litter retains Mn more strongly in the litter structure, producing humus richer in Mn than does litter of pine and deciduous species.

  • 4.
    Berg, Björn
    et al.
    Department of Forest Ecology, University of Helsinki, Helsinki, Finland.
    Johansson, Maj-Britt
    University of Gävle.
    Liu, Chunjiang
    School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China; Shanghai Urban Forest Research Station, State Forestry Administration, Shanghai, China.
    Faituri, Mikaeel
    Department of Soils and Water, Omar AlMukhtar University, Elbeida, Libya.
    Sanborn, Paul
    Ecosystem Science and Management Program, University of Northern British Columbia, Prince George, Canada.
    Vesterdal, Lars
    Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, Denmark.
    Ni, Xiangyin
    Long-term Research Station of Alpine Forest Ecosystems, Key Laboratory of Ecological Forestry Engineering, Institute of Ecology and Forestry, Sichuan Agricultural University, Chengdu, China.
    Hansen, Karin
    IVL Swedish Environmental Research Institute, Stockholm, Sweden.
    Ukonmaanaho, Liisa
    Natural Resources Institute Finland, Helsinki, Finland.
    Calcium in decomposing foliar litter – A synthesis for boreal and temperate coniferous forests2017In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 403, p. 137-144Article in journal (Refereed)
    Abstract [en]

    We have synthesized available data for calcium (Ca) dynamics in decomposing foliar litter of mainly pine (Pinus), spruce (Picea), and birch (Betula) species to determine patterns of Ca concentration with climate in newly shed litter and its dynamics in decomposing litter as well as a possible role for Ca as regards limit values. Initial Ca concentration was negatively related to mean annual precipitation (MAP) with different relationships among genera. A limited data set showed a positive relationship across species (p &lt; 0.05) to extractable Ca in soil. In paired stands, litter of both Norway spruce (Picea abies) and lodgepole pine (Pinus contorta) had higher Ca concentrations than Scots pine (Pinus silvestris), Norway spruce litter even twice as high. Relationships between initial concentrations of Ca and those of other nutrients appeared to be dominated by the positive ones to potassium (K) and magnesium (Mg) and specifically for deciduous litter there was a negative relationship to nitrogen (N). In decomposing litter, Ca concentration followed a negative quadratic (Ca = a + t − t2) function and had a maximum, which was variable. The Ca maximum concentration during decomposition was positively related to initial Ca concentration both within and among species. Separate linear relationships based on species were combined into one, in common for all investigated species and genera (R2 = 0.914, n = 63, p &lt; 0.001). Limit values for decomposition were positively related to maximum Ca concentration at p &lt; 0.05 with separate functions for pine and spruce litter. Calcium net release started directly after the incubation and was linear to accumulated mass loss of litter, giving a slope coefficient for each study. The net release rates were linear to initial Ca concentration both within and across species/genera. All studies combined gave a negative linear relationship (R2 = 0.894, n = 67, p &lt; 0.001).

  • 5.
    Berg, Björn
    et al.
    Department of Forest Ecology, University of Helsinki, Helsinki, Finlan; Dipartimento Biologia Strutturale e Funzionale, Complesso Universitario, Napoli, Italy.
    Johansson, Maj-Britt
    University of Gävle.
    Nilsson, Åke
    Department of Forest Soils, Swedish University of Agriculture, Uppsala, Sweden.
    Gundersen, Per
    Forest and Landscape Denmark, University of Copenhagen, HØrsholm, Denmark.
    Norell, Lennart
    Unit of Applied Statistics and Mathematics, Swedish University of Agrictulture, Uppsala, Sweden.
    Sequestration of carbon in the humus layer of Swedish forests - direct measurements2009In: Canadian Journal of Forest Research, ISSN 0045-5067, E-ISSN 1208-6037, Vol. 39, no 5, p. 962-975Article in journal (Refereed)
    Abstract [en]

    To determine sequestration rates of carbon dioxide (CO2) we calculated the carbon (C) storage rate in humus layers of Swedish forests with Podsolic soils, which account for 14.2 x 106 ha of the 22.7 x 106 ha of forested land in Sweden. Our data set covered 41 years of humus inventories and mean humus layer thickness in 82513 plots. We analysed three forest types: (i) all combinations of tree species, (ii) forests dominated (>70%) by Norway spruce (Picea abies (L.) Karst.), and (Ui) forests dominated (>70%) by Scots pine (Pinus sylvestris L.). To relate changes in humus layer thickness to land area we used the intersections in 25 km x 25 km grids and used kriging interpolation, permitting calculations for each forest type. For each intersection mean humus thickness for each year was calculated and regressed against time to obtain the rate of change. This rate, humus bulk density, and humus C concentration were used, to calculate sequestration rates. The mean sequestration rate was 251 kg C-ha-1'year1, which is higher than theoretical values. The sequestration rate was positively related to temperature sum, albeit including effects of forest management. The pine-dominated forest type had a mean rate of 283 kgCha⁁year-1, and. the spruce-dominated had a mean rate of 239 kg Cha-1-year1. Under similar site conditions, pine sequestered more C than spruce (difference of 71 kg Cha-1'year-1; p < 0.0001), showing the importance of this type of ecosystem for C sequestration.

  • 6.
    Berg, Björn
    et al.
    Department of Forest Sciences, University of Helsinki, Helsinki, Finland.
    Kjønaas, O. J.
    Norwegian Institute of Bioeconomy Research, Ås, Norway.
    Johansson, Maj-Britt
    University of Gävle.
    Erhagen, B.
    Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden.
    Åkerblom, S.
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden .
    Late stage pine litter decomposition: Relationship to litter N, Mn, and acid unhydrolyzable residue (AUR) concentrations and climatic factors2015In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 358, p. 41-47Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to evaluate relationships between decomposition rates of Scots pine (Pinus sylvestris) and lodgepole pine (Pinus contorta var. contorta) needle litter in the late stage of decomposition (>30% accumulated mass loss), and the progressively changing concentrations of manganese (Mn), nitrogen (N), and acid unhydrolyzable residue (AUR), as well as mean annual temperature (MAT) and mean annual precipitation (MAP). Using available long-term decomposition studies on pine needle litter in a climate gradient in Sweden, we calculated annual mass loss and related to concentrations of Mn, N, and AUR at the start of each one-year period as well as to MAT and MAP. We investigated these relationships for (i) all data on annual mass loss combined and (ii) annual mass loss for five different decomposition categories as defined by accumulated mass loss. We found highly significant, negative, and dominant relationships between annual mass loss and N (R2=0.39) and AUR (R2=0.39), a slight but significant positive relationship to Mn (R2=0.08) and a significant negative relationship to MAT (R2=0.06). The relationships were dynamic, and changed with accumulated mass loss. The rate-dampening effect of N decreased to be a rate-enhancing effect at c. 60-80% accumulated mass loss. A similar trend was found for AUR, becoming rate-enhancing at 70-80% accumulated mass loss. For Scots pine needle litter the effect of MAT on mass loss decreased with increasing accumulated mass loss and changed to a rate-dampening effect at c. 50-70% accumulated mass loss. Mn showed a stimulating effect on mass loss rate in all categories whereas MAP showed no effect in this mainly boreal climatic gradient. The current approach indicates a method for detailed studies of rate-regulating factors for litter decomposition. 

  • 7. Berggren Kleja, Dan
    et al.
    Svensson, M
    Majdi, Hooshang
    Langvall, O
    Jansson, P-E
    Lindroth, A
    Weslien, P
    Bergkvist, B
    Johansson, Maj-Britt
    Swedish University of Agricultural Sciences.
    Pools and fluxes of carbon in three Norway spruce ecosystems along a climatic gradient in Sweden2008In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 89, no 1, p. 7-25Article in journal (Refereed)
  • 8.
    Bringmark, Ewa
    et al.
    Department of Aquatic Sciences and Assessment, SLU, Uppsala, Sweden.
    Bringmark, Lage
    Department of Aquatic Sciences and Assessment, SLU, Uppsala, Sweden.
    Sonesten, Lars
    Department of Aquatic Sciences and Assessment, SLU, Uppsala, Sweden .
    Mjöfors, Kristina
    Department of Soil and Environment, SLU, Uppsala, Sweden.
    Johansson, Maj-Britt
    University of Gävle.
    Long-term monitoring of scots pine litter decomposition rates throughout sweden indicates formation of a more recalcitrant litter in the south2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 8, p. 878-890Article in journal (Refereed)
    Abstract [en]

    Decomposition studies were carried out at sites throughout Sweden, including the four Integrated Monitoring sites. Scots pine needle litterbag weight loss measurements over 3 or 5 years were determined at 26 sites and repeated up to 27 times, depending on the site. Humus layer respiration rates were determined for 20 sites in 1987-1989 and repeated in 2007-2008. Partial Least Squares (PLS) regression was used to elucidate the relative importance of climatic and soil factors. Annual needle weight losses decreased only slowly (20-10%) over 3-5 years for all northern (> 60A degrees N) sites but decreased sharply from 30 to 10% in the third year in southern (< 60A degrees N) sites. Respiration rates of southern sites were less (40% on average) than those of northern sites. Humus layer N was positively correlated to needle weight loss during the first and the second years, but negatively correlated in the third year and to respiration rates. The results indicated that litter formed in southern Sweden became more recalcitrant in later stages of decomposition compared to litter produced in northern Sweden.

  • 9.
    Mjöfors, Kristina
    et al.
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Strömgren, Monika
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Nohrstedt, Hans-Örjan
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Johansson, Maj-Britt
    University of Gävle, Vice-Chancellor's Office. Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Gärdenäs, Annemieke I.
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Indications that Site Preparation increases Forest Ecosystem Carbon Stocks in the Long-Term2017In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 32, no 8, p. 717-725Article in journal (Refereed)
    Abstract [en]

    Mechanical site preparation (MSP) causes a mixing disturbance of the soil, which may increase decomposition of soil organic matter and subsequent carbon (C) dioxide emissions to the atmosphere. MSP also promotes the establishment and growth of tree seedlings, and hence ecosystem C fixation. However, there are uncertainties regarding net effects of MSP on C stocks at the ecosystem scale. To assess decennial effects of MSP on ecosystem C stocks, C stocks in soil, ground vegetation and trees at three experimental forest sites with Pinus contorta, Pinus sylvestris and Picea abies in Sweden were sampled and measured ca. 25 years in a control and after three MSP treatments: disc trenching, mounding and ploughing. After 25 years, all of the MSP treatments resulted in larger ecosystem C stocks than the control treatment due to positive effects on the tree biomass C stock. The tree C stock was highest after ploughing, intermediate after mounding or disc trenching, and lowest in untreated control plots at all experimental sites. The MSP treatments did not affect the soil C stocks down to 30 cm. We recommend mounding or disc trenching to promote C sequestration as they disturb sites’ ecological, aesthetic and recreational values less than ploughing.

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