Survival of the Deepest Peatlands? Peat Depth as a Driver of Ecohydrological Resilience to Drought and Wildfire Journal Articles uri icon

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abstract

  • <p>Northern peatlands provide important ecosystem services (<em>e.g.</em> carbon storage, water storage, species at risk habitat). While these ecosystems are facing large increases in the areal extent and frequency of climate-mediated disturbances (<em>e.g.</em> wildfire, drought), they are generally resilient to these disturbances. Numerous autogenic ecohydrological feedbacks operate within peatlands that regulate their response to changes in seasonal water deficit. However, the foundational research upon which this peatland resilience framework understanding was based were undertaken in deep and large peatlands where a water table (WT) is ever-present. In contrast, little research has been undertaken on shallow and small-scale peat-accumulating systems and as such their vulnerability to disturbance remains unknown. To address this research gap, this study examines the ecohydrological processes that control water storage dynamics, moss water stress, depth of burn, and carbon fluxes in peatlands varying in average peat depth.</p> <p>Shallower peatlands had greater water table variability, water table depths, water table drawdown rates, moss moisture stress and depths of burn than deeper peatlands. Moreover, peatland gross ecosystem productivity sequestration was significantly lower during periods when water table dropped below the peat layer. Mean summer water table depth was found to be significantly correlated with summer total net ecosystem CO<sub>2</sub> exchange (R<sup>2</sup>adj = 0.923 ; <em>p-value </em>= 0.029) and GEP (R<sup>2</sup>adj = 0.994 ; <em>p-value </em>= 0.003), where wet summers with a water table  close to the peat surface sequestered more than twice the amount of CO<sub>2</sub> than dry summers. These results suggest that peat depth is important in controlling the strength and sign of autogenic ecohydrological feedbacks and in determining peatland vulnerability to drought and wildfire. Moreover, this study provides insight into both the evolution of the optimality of peatland ecosystems and potential adaptation strategies to minimize the vulnerability of shallow and/or recently restored peatlands to drought.  </p>

publication date

  • February 22, 2023