Emerging forest–peatland bistability and resilience of European peatland carbon stores

Abstract

Northern peatlands store large amounts of carbon. Observations indicate that forests and peatlands in northern biomes can be alternative stable states for a range of landscape settings. Climatic and hydrological changes may reduce the resilience of peatlands and forests, induce persistent shifts between these states, and release the carbon stored in peatlands. Here, we present a dynamic simulation model constrained and validated by a wide set of observations to quantify how feedbacks in water and carbon cycling control resilience of both peatlands and forests in northern landscapes. Our results show that 34% of Europe (area) has a climate that can currently sustain existing rainwater-fed peatlands (raised bogs). However, raised bog initiation and restoration by water conservation measures after the original peat soil has disappeared is only possible in 10% of Europe where the climate allows raised bogs to initiate and outcompete forests. Moreover, in another 10% of Europe, existing raised bogs (concerning ∼20% of the European raised bogs) are already affected by ongoing climate change. Here, forests may overgrow peatlands, which could potentially release in the order of 4% (∼24 Pg carbon) of the European soil organic carbon pool. Our study demonstrates quantitatively that preserving and restoring peatlands requires looking beyond peatland-specific processes and taking into account wider landscape-scale feedbacks with forest ecosystems.

Where should hydrology go? An early-career perspective on the next IAHS Scientific Decade: 2023-2032

“…Hydrological disciplines in which tipping points have been identified include surface runoff (Dijkstra et al, 2019;Dunne and Black, 1970a;Horton, 1945), groundwater (Bailey, 2011;Figura et al, 2011), hydrometeorology (Buitink et al, 2020;Denissen et al, 2020;Krishnamurthy R et al, 2020), ecohydrology (Hirota et al, 2011;Mayor et al, 2019), and water quality (Dakos et al, 2019;Dijkstra et al, 2019). Moreover, these tipping points manifest themselves in all places: from arctic (Devoie et al, 2019;Rosier et al, 2021) to temperate climates (Kupec et al, 2021;van der Velde et al, 2021), from wet 10 (Loverde- Oliveira et al, 2009;Verbesselt et al, 2016) to arid regions (Bailey, 2011;Bernardino et al, 2020), and from hydrological source (Marty, 2008) to sink (Kirwan and Megonigal, 2013).…”

Can ash from smoldering fires increase peatland soil pH?

“…Turetsky et al 2015) and store an estimated ∼600 Gt of carbon (Yu et al 2010;Page et al 2011). However, the carbon storage can become compromised when peatlands become degraded or disturbed (van der Velde et al 2021), for example by changes in land-use and climate (Leifeld and Menichetti 2018). Moisture stress or lowering water levels can cause shifts in the peatlands' carbon sink functionality (Salimi et al 2021), and potentially shift the system from a net sink to a net source of carbon (e.g.…”

A resilience sensing system for the biosphere

“…Existing studies (table 1) examine just a small subset of ecosystems, but they overlap with some particularly vulnerable ones including Mediterranean vegetation, savannahs and California woodland. Some ecosystems may be particularly vulnerable to abrupt change and/or tipping points due to localized feedbacks, including forests subject to dieback [89], peatlands [90] and regularly patterned vegetation [91] (although see [92] on the latter). Indeed, analysis of Californian forests at fine spatial and temporal resolution has revealed statistical early warning signals of rising AR(1) of NDVI prior to forest dieback mortality events [26], increasing confidence that resilience sensing can help highlight where tipping points may be prone to occurring.…”