Peat bogs; Climate warming; Soil enzymes; Soil organic carbon; Microbial diversity; Plant-microbe interactions; Primary production; peatlands; nitrogen; vegetation biomass; Sphagnum; soil chemistry
Bragazza Luca, Bardgett Richard D., Mitchell Edward A. D., Buttler Alexandre (2015), Linking soil microbial communities to vascular plant abundance along a climate gradient, in New Phytologist
, 205(3), 1175-1182.
Bragazza L. Parisod J Buttler A. & Bardgett R. (2013), Biogeochemical plant-soil microbe feedback in response to climate warming in peatlands, in Nature Climate Change
Lamentowicz M Bragazza L Buttler A Jassey VEJ Mitchell EAD (2013), Seasonal patterns of testae amoebae diversity, community structure and species-environment relationships in four Sphganum-dominated peatlands along a 1300 m altitudinal gradient in Switzerland, in Soil Biology and Biochemistry
Robroek BJM Heijboer A Jassey VEJ Hefting MM Rouwenhorst TG Buttler A Bragazza L (2013), Snow cover manipulation effects on microbial community structure and soil chemistry in a mountain bog, in Plant and Soil
, 369, 152-164.
Peatlands are important long-term carbon (C) sinks, particularly Sphagnum-dominated peatlands (or bogs) where the bulk of living and dead biomass is formed by Sphagnum mosses. This peculiar genus of bryophytes is characterized by physiological and biochemical features that enhance the sequester of C by the production of litter extremely refractory to decomposition and by the presence of microbial inhibitors. Furthermore, Sphagnum productivity is strictly dependent on water surplus so that bogs are expected to be particularly sensitive to climate change. Indeed, any reduction of Sphagnum dominance in favour of vascular plants can jeopardize the C sink function of bogs because the litter of vascular plant is much more easily decomposable. Any increase of vascular plant productivity is necessarily mediated by soil microbes, whose decomposing activity releases nutrients for root absorbance and plant growth. Some laboratory experiments suggest that increasing peat soil temperature can promote the growth of vascular plants at expense of mosses through an alteration of plant competitive ability for nutrient acquisition with respect to soil microbes. In the light of the ongoing climate change, a better understanding of the effects of climate warming on plant-microbe interactions in bogs is then crucial for predicting potential alteration on C sinking mediated by above- and belowground feedbacks. The main aim of the present research project is then to understand the relationships between plants and microbes for nutrient acquisition (C, N and P) and potential feedbacks on bog biogeochemistry along a gradient of increasing peat soil temperature. Increasing peat soil temperature will be obtained by selecting the study bogs along an altitudinal gradient so as to assess the effects of climate warming under conditions of long-term equilibrium between biogeochemistry, vegetation and local climatic conditions. The research project will include both field observations along one entire year (so as to include also the winter season), but it will also include a mesocosm experiment where peat monoliths will be transplanted to lower altitude so as to study the biological and physico-chemical reactions of the system to a sudden climate change. By means of information concerning soil enzymatic activity, microbial diversity and abundance, plant biomass and productivity, peat and water chemistry, we want to test the following main hypotheses and clarify the underlying mechanisms:1) microbial biomass is higher during summer months when the plant growth is higher and it is negatively correlated with the altitude;2) enzymatic activity is higher during summer months to face a higher nutrient request by growing plants and it decreases along the altitudinal gradient as a consequence of a lower peat temperature;3) the standing biomass of vascular plant decreases with altitude, but Sphagnum productivity increases with altitude; in addition, we hypothesize that vascular plant nutrient content is higher at lower altitude;4) higher peat temperature will stimulate a higher rhizodeposition, mirrored in a higher concentration of polyphenols in bog water, with potential lower microbial immobilization of nutrient during summer months.