Resilience of peatland ecosystem services over millennial timescales: evidence from a degraded British bog

Abstract

Summary Many peatland ecosystems in Europe have become degraded in the last century owing to the effects of drainage, burning, pollution and climate change. There is a need to understand the drivers of peatland degradation because management and restoration interventions are expensive and can affect the natural ecohydrological dynamics of such sensitive environments. However, if given enough time, peatlands may have the ability to recover spontaneously without deliberate action. We use a detailed multiproxy palaeoecological data set from a degraded raised bog in Northern England to examine its ecosystem stability and long‐term dynamics in response to anthropogenic disturbance over a variety of timescales. One feature of many degraded peatlands (including our study site) is the local dominance of Molinia caerulea (purple moor‐grass), which has expanded at the expense of characteristic peatland plants, including sedges and Sphagnum mosses. Our data show that there has been a long history of human impacts at the site which have culminated in its current unfavourable condition. Several distinct episodes of past peat cutting are evident as hiatuses in peat accumulation; however, peat accumulation and plant community structure have subsequently recovered spontaneously. The appearance of M. caerulea occurs coevally with an unprecedented variety of recent anthropogenic impacts, all of which have contributed to providing a suitable environment for its rise to dominance. We have dated the appearance of M. caerulea to the latter half of the twentieth century which corresponds to a number of anthropogenic press disturbances, including the following: dust loading from post‐war expansion of the adjacent quarry; burning; drainage; airborne pollution; and contamination from soil dust and agrochemicals. [Synthesis] Our study demonstrates the importance of palaeoecology for understanding the trajectories of peatland development and ecosystem dynamics, including their resilience and resistance to pulse and press disturbances. We show that peatlands have the capability to recover spontaneously from severe disturbances such as peat cutting, albeit on timescales much longer than those applied to contemporary monitoring of restoration efforts. The implications are relevant for determining whether it is preferable to manage and restore peatlands, or to allow them to recover naturally without human intervention.

Ecosystem state shifts during long‐term development of an Amazonian peatland

“…Drought phase B potentially drove the conversion of the forest swamp into an ombrotrophic peat dome, again by stimulating productivity in a previously seasonally flooded landscape. The resumption of peat accumulation after drought phase C also adds further weight to the growing body of evidence for the resilience of peatland ecosystems to recover from severe disturbances (e.g., Morris, Baird, Young, & Swindles, ; Swindles, Lamentowicz et al., ; Swindles, Morris et al., ; Waddington et al., ). The shift to ombrotrophic peat dome at ca.…”

“…The most common testate amoebae in the profile include Hyalosphenia subflava , Trigonopyxis arcula , Phryganella acropodia and Centropyxis aculeata . Preservation down‐core is variable and concentrations of testate amoebae in general were very low (see Swindles, Lamentowicz et al., ; Swindles, Morris et al., ). The horizon 50–60 cm (peat dome phase) was barren of testate amoebae.…”

“…(), and Swindles, Morris et al. (). Subfossil testate amoebae were counted under transmitted light at 200–400× magnification and identified using morphology, composition, size, and colour to distinguish taxa.…”

“…Previous research in the PMFB has included preliminary determinations of peat C content, physical properties, and geochemistry (Lähteenoja & Page, ; Lähteenoja, Ruokolainen, Schulman, & Alvarez, ; Lähteenoja, Ruokolainen, Schulman, & Oinonen, ; Lähteenoja et al., ), remote sensing of peatland ecosystems (Draper et al., ), and palynological studies (Kelly et al., ; Roucoux et al., ). There have also been studies of the ecology and palaeoecology of testate amoebae (Reczuga, Swindles, Grewling, & Lamentowicz, ; Swindles et al., ; Swindles, Lamentowicz, Reczuga, & Galloway, ; Swindles, Morris et al., ). Watson, Swindles, Savov, and Bacon () reported the presence of microscopic tephra (volcanic ash) in a peat core, tentatively attributed to a source in the Ecuadorian Eastern Cordillera.…”

The application of resilience concepts in palaeoecology

“…Numerous studies (24% of direct definitions) mention both forms of resilience, represented by differences between sites or by a change in the type of resilience through time (e.g. Bhagwat et al 2012, Lopez-Merino et al 2012, Macken and Reed 2014, Kowlalewski et al 2015, Ryan et al 2016, Swindles et al 2016. Coastal geomorphology "This research leads us to reflect on the concept of "coastal resilience" which, we conclude, means little without a clearly defined spatial and temporal framework... We therefore envisage multiple scales of "resilience" operating simultaneously across the complex, responding to different forcing agents with particular magnitudes and frequencies… "Coastal resilience" describes the self-organising ability of a coast to respond in a sustainable manner to morphological, biological and/or socio-economic pressures" (Long et al 2006: 309-310) Direct: ecological resilience (tolerance or reorganisation)…”