3 research outputs found
Assessing the responses of Sphagnum micro-eukaryotes to climate changes using high throughput sequencing
Current projections suggest that climate warming will be accompanied by more frequent and severe drought events. Peatlands store ca. one third of the worldâs soil organic carbon. Warming and drought may cause peatlands to become carbon sources through stimulation of microbial activity increasing ecosystem respiration, with positive feedback effect on global warming. Micro-eukaryotes play a key role in the carbon cycle through food web interactions and therefore, alterations in their community structure and diversity may affect ecosystem functioning and could reflect these changes. We assessed the diversity and community composition of Sphagnum-associated eukaryotic microorganisms inhabiting peatlands and their response to experimental drought and warming using high throughput sequencing of environmental DNA. Under drier conditions, micro-eukaryotic diversity decreased, the relative abundance of autotrophs increased and that of osmotrophs (including Fungi and Peronosporomycetes) decreased. Furthermore, we identified climate change indicators that could be used as early indicators of change in peatland microbial communities and ecosystem functioning. The changes we observed indicate a shift towards a more âterrestrialâ community in response to drought, in line with observed changes in the functioning of the ecosystem
Meeting Report: 7th International Symposium on Testate Amoebae (ISTA-7), PoznaĆ, Poland, 8â12 September 2014 - Research Priorities, Progress and Present Status of Testate Amoeba Research
Ericoid shrub encroachment shifts abovegroundâbelowground linkages in three peatlands across Europe and Western Siberia
Abstract In northern peatlands, reduction of Sphagnum dominance in favour of vascular vegetation is likely to influence biogeochemical processes. Such vegetation changes occur as the water table lowers and temperatures rise. To test which of these factors has a significant influence on peatland vegetation, we conducted a 3âyear manipulative field experiment in Linje mire (northern Poland). We manipulated the peatland water table level (wet, intermediate and dry; on average the depth of the water table was 17.4, 21.2 and 25.3âcm respectively), and we used openâtop chambers (OTCs) to create warmer conditions (on average increase of 1.2°C in OTC plots compared to control plots). Peat drying through water table lowering at this local scale had a larger effect than OTC warming treatment per see on Sphagnum mosses and vascular plants. In particular, ericoid shrubs increased with a lower water table level, while Sphagnum decreased. Microclimatic measurements at the plot scale indicated that both waterâlevel and temperature, represented by heating degree days (HDDs), can have significant effects on the vegetation. In a largeâscale complementary vegetation gradient survey replicated in three peatlands positioned along a transitional oceanicâcontinental and temperateâboreal (subarctic) gradient (FranceâPolandâWestern Siberia), an increase in ericoid shrubs was marked by an increase in phenols in peat pore water, resulting from higher phenol concentrations in vascular plant biomass. Our results suggest a shift in functioning from a mineralâNâdriven to a fungiâmediated organicâN nutrient acquisition with shrub encroachment. Both ericoid shrub encroachment and higher mean annual temperature in the three sites triggered greater vascular plant biomass and consequently the dominance of decomposers (especially fungi), which led to a feeding community dominated by nematodes. This contributed to lower enzymatic multifunctionality. Our findings illustrate mechanisms by which plants influence ecosystem responses to climate change, through their effect on microbial trophic interactions