Water level drawdown makes boreal peatland vegetation more responsive to weather conditions

Köster, Egle; Chapman, Jack P. B.; Barel, Janna M.; Korrensalo, Aino; Laine, Anna M.; Vasander, Harri T.; Tuittila, Eeva‐Stiina

doi:10.1111/gcb.16907

Cited by 8 publications

(4 citation statements)

References 99 publications

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“…The growth of organic matter ore and the flow of carbon and nitrogen may be enhanced by drainage-saturated conditions that alternate between anaerobic and aerobic environments. In poor fen and bog, WTD increased plant growth, while in rich fen, WTD reduced the growth of ground-level vegetation [43]. Sphagnum is the most important plant for the accumulation of peat, and is one of the dominant species in nutrient-poor peatland [44,45].…”

Section: Discussionmentioning

confidence: 99%

A Comparison of Greenhouse Gas Emission Patterns in Different Water Levels in Peatlands

Peng,

Li,

Yang

et al. 2024

Water

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Peatlands store large amounts of carbon in wetland ecosystems. The hydrological conditions within peatlands are important factors that affect the biochemical cycle and patterns of greenhouse gas emissions in these peatlands. This study was carried out in Changbai Mountain Jinchuan peatland to investigate variations in carbon dioxide and methane emissions in peat swamps that have undergone distinct saturation conditions. Three peatland types (high water levels (S1); medium water levels (S2); low water levels (S3)) at different flood depths were selected as specific sampling points. The static box and gas chromatography methods were used at different time periods (6:00; 12:00; and 18:00) from July to September. The discharge flux of CO2 and CH4 slowly increased with the increase in the water level. The results indicate similarity in the fluctuation trends between the fluxes of CO2 and CH4 in S1 and S2 to the fluctuations of water levels. During the entire growth season, the flux range of CO2 and CH4 was −695.329~859.907 mg m2h−1 and 259.981~147.155 mg m2h−1, respectively. Furthermore, there was variation in mutation characteristics between two gases, the CO2 exhibited larger mutation range (−7.08~3.40)than CH4 (−1.79~1.26). In terms of daily flux changes, CO2 showed an upward trend, while CH4 had a downward trend. These results indicate variations in saturation conditions tend to affect discharge of greenhouse gases, with subsequent effects on climate change. This study highlights potential theoretical support to reduce anthropogenic activities on peatlands. This can be achieved by undertaking measures to conserve peatlands and explore mitigation measures to minimize greenhouse gas emissions and hence impacts of climate change.

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Section: Discussionmentioning

confidence: 99%

A Comparison of Greenhouse Gas Emission Patterns in Different Water Levels in Peatlands

Peng,

Li,

Yang

et al. 2024

Water

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“…WLD strengthens acquisitive plant traits, including Pmax and plant height, on nutrient-rich sites such the rich fen, while little change occurs in nutrient-limited bogs (Laine et al, 2021). The result is a fundamental change in the ecosystem structure of rich fens following WLD from open peatland vegetation to a canopy of vascular plants dominated by dryland species (Köster et al, 2023). The initial stability after WLD of dry-adapted hummock communities disappears as the new sheltering environment drives secondary changes in ground vegetation (Köster et al, 2023).…”

Section: Drying-induced Changes In the Vegetation Communitymentioning

confidence: 99%

“…The result is a fundamental change in the ecosystem structure of rich fens following WLD from open peatland vegetation to a canopy of vascular plants dominated by dryland species (Köster et al, 2023). The initial stability after WLD of dry-adapted hummock communities disappears as the new sheltering environment drives secondary changes in ground vegetation (Köster et al, 2023). Under a canopy, where light becomes limited and evaporation decreases (Minkkinen et al, 1999;Straková et al, 2012), the functional traits and photosynthetic response of plants adjusts to the new environment (Hájek et al, 2009;Kangas et al, 2014;Laine et al, 2021).…”

Section: Drying-induced Changes In the Vegetation Communitymentioning

confidence: 99%

The impact of drying on the structure and photosynthesis of boreal peatland vegetation

Kokkonen

2024

Diss. For.

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Boreal peatlands harbour large stores of carbon as peat below their surfaces. Climate change is expected to cause drying in northern peatlands, which will in turn impact the carbon balance of these ecosystems that is maintained by high water tables and the hydrologically sensitive plants growing there. This study aims to quantify how vegetation will be structured (I) and photosynthesize (II, III) in a future climate as emulated by long-term water level drawdown (WLD). To do this, changes in the vegetation and its photosynthesis after WLD are linked, and the response of Sphagnum mosses to periodic drought is investigated. Field measurements were done at a long-term WLD field experiment that contained a rich (mesotrophic) fen, a poor (oligotrophic) fen and a bog (ombrotrophic) site. Measurements included vegetation surveys from existing permanent sample plots and leaf-level carbon dioxide exchange measurements. For an experiment in controlled conditions peatland surface cores from this field experiment were transported to a greenhouse where the photosynthesis of lawn Sphagna during and after an experimental periodic drought was measured. The field study revealed that the response of peatland vegetation to WLD depend on peatland type. The species composition in the rich fen was the most impacted by WLD, while the bog vegetation demonstrated stability. Similarly, large increases in photosynthesis occurred following WLD on the vascular plant-covered rich fen, while changes were negligible on the Sphagnum-carpeted bog. The vegetation on the two fens shifted from an open sedge-, or sedge and Sphagnum-dominated ecosystem, to a tree-dominated ecosystem. Canopy development following WLD further accelerated vegetation changes by shading and sheltering the understorey vegetation. Vascular plants were the most likely to increase productivity from WLD as they are best suited to utilize the nutrients made available by peat mineralization, while Sphagnum moss photosynthesis was impacted little. The greenhouse study revealed that lawn Sphagnum mosses exposed to long-term WLD were more vulnerable to drought compared to those from wet sites. Large capitula typical to fen Sphagnum species appeared to be beneficial for surviving periodic drought. This work demonstrated that climate change as emulated by long-term WLD will have a large impact on the vegetation composition of northern peatlands and increase photosynthetic function of these ecosystems, fens in particular. To better predict climate feedbacks from these changes, carbon dynamics including peatland vegetation dynamics should be updated in global process models. Future research to better understand the tipping point of different peatland types after WLD in different climatic regions will help us to predict changes in these diverse and globally important systems.

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“…Third, exposure to long-term deep or deepened water tables may increase the vulnerability of Sphagna as the stress of dry habitats may have a cumulative impact when combined with periodic drought. This would increase the ecosystem's vulnerability to extreme events by moving the ecosystem closer to its tipping point where its structure and function irreversibly change (Köster et al, 2023;Thormann et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

A deepened water table increases the vulnerability of peat mosses to periodic drought

Kokkonen,

Laine,

Korrensalo

et al. 2024

Journal of Ecology

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Here we address the combined impact of multiple stressors that are becoming more common with climate change. To study the combined effects of a lower water table (WT) and increased frequency of drought periods on the resistance and resilience of peatlands, we conducted a mesocosm experiment. This study evaluated how the photosynthesis of lawn Sphagnum mosses responds to and recovers from an experimental periodic drought after exposure to the stresses of a deep or deepened WT (naturally dry and 17‐year‐long water level drawdown [WLD] in fen and bog environments). We aimed to quantify if deep WTs (1) support acclimation to drought, or (2) increase the base‐level physiological stress of mosses or (3) exacerbate the impact of periodic drought. There was no evidence of acclimation in mosses from drier environments; periodic drought decreased the photosynthesis of all Sphagnum species studied. WLDdecreased the photosynthesis of bog‐originating mosses prior to periodic drought, indicating that these mosses were stressed by the hydrological change. Deep WTs exacerbated Sphagnum vulnerability to periodic drought, indicating that the combination of drying habitats and increasing frequency of periodic drought could lead to a rapid transition in lawn vegetation. Water‐retaining traits may increase Sphagnum resilience to periodic drought. Large capitula size was associated with a higher resistance; the bog originating species studied here lacked large capitula or dense carpet structure and were more vulnerable to drought than the larger fen originating species. Consequently, lawns in bogs may become threatened. Recovery after rewetting was significant for all mosses, but none completely recovered within 3 weeks. The most drought‐resilient species had fen origin, indicating that fens are less likely to undergo a sudden transition due to periodic drought. Synthesis: Water level drawdown associated with climate change increases the sensitivity of Sphagnum mosses to periods of drought and moves them closer to their tipping point as species on the edge of their ecological envelope rapidly shut down photosynthesis and recover poorly.

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Water level drawdown makes boreal peatland vegetation more responsive to weather conditions

Cited by 8 publications

References 99 publications

A Comparison of Greenhouse Gas Emission Patterns in Different Water Levels in Peatlands

A Comparison of Greenhouse Gas Emission Patterns in Different Water Levels in Peatlands

The impact of drying on the structure and photosynthesis of boreal peatland vegetation

A deepened water table increases the vulnerability of peat mosses to periodic drought

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