20 research outputs found

    Litter quality and its response to water level drawdown in boreal peatlands at plant species and community level

    Get PDF
    Changes in the structure of plant communities may have much more impact on ecosystem carbon (C) cycling than any phenotypic responses to environmental changes. We studied these impacts via the response of plant litter quality, at the level of species and community, to persistent water-level (WL) drawdown in peatlands. We studied three sites with different nutrient regimes, and water-level manipulations at two time scales. The parameters used to characterize litter quality included extractable substances, cellulose, holocellulose, composition of hemicellulose (neutral sugars, uronic acids), Klason lignin, CuO oxidation phenolic products, and concentrations of C and several nutrients. The litters formed four chemically distinct groups: non-graminoid foliar litters, graminoids, mosses and woody litters. Direct effects of WL drawdown on litter quality at the species level were overruled by indirect effects via changes in litter type composition. The pristine conditions were characterized by Sphagnum moss and graminoid litters. Short-term (years) responses of the litter inputs to WL drawdown were small. In longterm (decades), total litter inputs increased, due to increased tree litter inputs. Simultaneously, the litter type composition and its chemical quality at the community level greatly changed. The changes that we documented will strongly affect soil properties and C cycle of peatlands.Peer reviewe

    Mineralisation of C and N from root, stem and leaf residues in soil and role of their biochemical quality

    Full text link
    The influence of biochemical characteristics of 15 crop residues on C and N mineralisation in soil was investigated by following the decomposition of roots, stems and leaves of four subtropical species and one temperate species buried into the soil. The C, N and polyphenols contents were measured in different biochemical pools obtained from residues of the different organs. The mineralisation of root C was significantly lower than that of leaves and stems. Chemical analysis showed a higher polyphenol content in the leaves and a higher ligninlike content in the roots. Carbon and N mineralisation were simulated with the STICS decomposition submodel and tested against the data set. The model predicted leaf and stem C mineralisation for all five species fairly accurately, but failed to predict root C mineralisation, indirectly revealing the more complex composition of the root tissue. The results showed the interest of separately considering the different plant parts when studying plant residue decomposition and the need to develop other methods of residue quality characterisation to improve the prediction of residue decomposition
    corecore