Extreme climate events are predicted to become more frequent and intense. Their ecological impacts, particularly on carbon cycling, can differ in relation to ecosystem sensitivity. Peatlands, being characterized by peat accumulation under waterlogged soil, can be particularly sensitive to climate extremes if the climate event increases soil oxygenation. However, a mechanistic understanding of peatland responses to persistent climate extremes is still lacking, particularly in terms of aboveground-belowground feedback. Here we present the results of a transplantation experiment of peat mesocosms from high to low altitude in order to simulate, during three years, a mean annual temperature c. 5°C higher and a mean annual precipitation c. 60% lower. Specifically, we aim at understanding the intensity of changes for a set of biogeochemical processes and their feedback on carbon accumulation. In the transplanted mesocosms, plant productivity showed a species-specific response depending on plant growth forms, with a significant decrease (c. 60%) of peat moss productivity. Soil respiration almost doubled and Q10 halved in the transplanted mesocosms in combination with an increase of activity of soil enzymes. Spectroscopic characterization of peat chemistry in the transplanted mesocosms confirmed the deepening of soil oxygenation which, in turn, stimulated microbial decomposition. After three years, soil carbon stock increased only in the control mesocosms whereas a reduction of mean annual carbon accumulation of c. 30% was observed in the transplanted mesocosms. Based on the above information, a structural equation model was built to provide a mechanistic understanding of the causal connections between peat moisture, vegetation response, soil respiration and carbon accumulation. This study identify in the feedback between plant and microbial responses the primary pathways explaining the reduction of carbon accumulation in response to recurring climate extremes in peat soils. This article is protected by copyright. All rights reserved.
Persistent high temperature and low precipitation reduce peat carbon accumulation
ZACCONE C.;
2016-01-01
Abstract
Extreme climate events are predicted to become more frequent and intense. Their ecological impacts, particularly on carbon cycling, can differ in relation to ecosystem sensitivity. Peatlands, being characterized by peat accumulation under waterlogged soil, can be particularly sensitive to climate extremes if the climate event increases soil oxygenation. However, a mechanistic understanding of peatland responses to persistent climate extremes is still lacking, particularly in terms of aboveground-belowground feedback. Here we present the results of a transplantation experiment of peat mesocosms from high to low altitude in order to simulate, during three years, a mean annual temperature c. 5°C higher and a mean annual precipitation c. 60% lower. Specifically, we aim at understanding the intensity of changes for a set of biogeochemical processes and their feedback on carbon accumulation. In the transplanted mesocosms, plant productivity showed a species-specific response depending on plant growth forms, with a significant decrease (c. 60%) of peat moss productivity. Soil respiration almost doubled and Q10 halved in the transplanted mesocosms in combination with an increase of activity of soil enzymes. Spectroscopic characterization of peat chemistry in the transplanted mesocosms confirmed the deepening of soil oxygenation which, in turn, stimulated microbial decomposition. After three years, soil carbon stock increased only in the control mesocosms whereas a reduction of mean annual carbon accumulation of c. 30% was observed in the transplanted mesocosms. Based on the above information, a structural equation model was built to provide a mechanistic understanding of the causal connections between peat moisture, vegetation response, soil respiration and carbon accumulation. This study identify in the feedback between plant and microbial responses the primary pathways explaining the reduction of carbon accumulation in response to recurring climate extremes in peat soils. This article is protected by copyright. All rights reserved.
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