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CLIMPEAT: HYPOTHESES

Higher temperature in combination with dryness will induce a shift from a Sphagnum-dominated system to a vascular plant-dominated system.

• If there is no water limitation, temperature increase enhances growth of both mosses and vascular plants (especially the above ground biomass allocation), but mosses will outcompete vascular plants.

• If there is water limitation, the better performance of vascular plants could facilitate, in a early stage, Sphagnum growth due to microclimate effect (i.e. shading partly compensates for the lower water table due to higher evapotranspiration), but in a later stage vascular plants will outcompete Sphagnum mosses. This is partly due to the better use of soil water by vascular plants and the higher dependency of mosses towards atmospheric humidity.

A rise in temperature in combination with drought changes the interaction between plants and microbes for the N and P acquisition in favor of nutrient acquisition by vascular plants.

• Higher peat temperature and dryness will stimulate a higher rhizodeposition by vascular plants, mirrored in a higher concentration of polyphenols in bog water, with potential lower microbial immobilization of nutrients during summer months (increased microbial C/N ratio).

• Soil enzymatic activity will be triggered to face the higher nutrient demand by growing vascular plants.

• Vascular plants increase their N and P content, which will in turn increases their decomposability.

A rise in temperature in combination with drought induces changes in primary net plant production and soil respiration, thus resulting in a modification of the carbon balance.

• If there is no water limitation the Net C exchange will be positive, with an increased carbon sequestration.

• If there is water limitation, the soil respiration will be increased and soil/water DOC will increase as well.

A change in soil temperature and/or humidity will change microbial community structure, diversity and biomass, but responses will vary among the taxonomic and functional groups. The fungi/bacteria ration will increase with drought and the microbial community will shift to be more heterotrophic-dominated.

The responses in community structure, biodiversity and OM composition can be used, alone or in combination, as 1) indicators of temperature-induced changes in the functioning of the eco-system, 2) to reconstruct climatic changes during the last 2000 years and 3) to predict future effects of climate changes.

There was a gradual decrease in carbon accumulation rate during the last millennium. Hydro-logical instability started in Little Ice Age and continued until today reinforced by mire dehydration ca 50 years ago.

CLIMPEAT Project

Joint research project
Experimental site

Aim of the project

Hypotheses

Innovative character

Summary

 

Work Packages

Experimental setting and environmental monitoring
Vegetation monitoring, plant standing biomass, net primary production and total nutrient content in plants

Microbial biomass and microbial diversity

Soil enzymatic activities

Micrometeorology, carbon accumulation, soil respiration and litter decomposition

Microcosm experiment (Neuchâtel)

Drought palaeohydrology and carbon accumulation during the last 1000 years

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