Erosion in peatlands: Recent research progress and future directions

Abstract

Peatlands cover approximately 2.84% of global land area while storing one third to one half of the world's soil carbon. While peat erosion is a natural process it has been enhanced by human mismanagement in many places worldwide. Enhanced peat erosion is a serious ecological and environmental problem that can have severe on-site and off-site impacts. A 2007 monograph by Evans and Warburton synthesized our understanding of peatland erosion at the time and here we provide an update covering: i) peat erosion processes across different scales; ii) techniques used to measure peat erosion; iii) factors affecting peat erosion; and iv) meta-analyses of reported peat erosion rates. We found that over the last decade there has been significant progress in studying the causes and effects of peat erosion and some progress in modelling peat erosion. However, there has been little progress in developing our understanding of the erosion processes. Despite the application of new peat surveying techniques there has been a lack of their use to specifically understand spatial and temporal peat erosion dynamics or processes in a range of peatland environments. Improved process understanding and more data on rates of erosion at different scales are urgently needed in order to improve model development and enable better predictions of future peat erosion under climate change and land management practices. We identify where further research is required on basic peat erosion processes, application of new and integrated measurement of different variables and the impact of drivers or mitigation techniques that may affect peat erosion.

Sediment and fluvial particulate carbon flux from an eroding peatland catchment

“…Numerous studies have suggested that peatlands can be both sinks and sources of carbon to the environment (Holden et al, ; Clay et al, ). Land management practices and pollution have led to disturbance of peat surfaces, resulting in large areas being extensively eroded (Li et al, , ) or under increasing erosion risk (Li et al, , ) in many peatlands of the UK. The physical disturbance of peat by weathering processes (e.g.…”

“…Weathering processes such as frost action and desiccation play an important role in supplying erodible peat particles for fluvial transport (Shuttleworth et al, ; Li et al, ). Frost weathering – resulting from the freezing and thawing of water between peat particles – is common in cool, high‐latitude or high‐altitude climates which support many peatlands.…”

Contextualising UK moorland burning studies: geographical versus potential sponsorship-bias effects on research conclusions

“…Thus we have confidence in the temperature data from our study sites. If the EMBER temperature sensors were exposed to the sun periodically as claimed by A&H this provides no explanation for why: (i) significantly higher temperatures were recorded over the study period with sensors that were buried at 5cm depth in the most recently burned patches (B2 plots, burned less than two years prior to measurements) (Brown et al, 2015) -the surface must have been warmer also; (ii) exposure to sunlight cannot explain why the very lowest temperatures were also recorded in the B2 plots, which in turn would enhance soil ice formation and erosion processes (Li et al, 2018a, Li et al, 2018b; (iii) re-analysis of the peat temperature data from the EMBER plots with the top 10% of disturbance values removed match those presented in Brown et al (2015), although the magnitude of the disturbances was, of course, reduced (Table 3). Notably though, removal of the top 10% of the highest temperatures increased the effect size for 6/7 burned plots where there was a statistically significant increase in temperature compared to B15+ plots (plots last burned more than 15 years prior to measurement).…”

Patterns and drivers of peat topographic changes determined from Structure‐from‐Motion photogrammetry at field plot and laboratory scales

“…Fleet Moss (SD 86 83; 54°07 0 N, 2°16 0 W) is an area of approximately 1.0 km 2 with deep upland blanket peat at an altitude of 550-580 m in the Yorkshire Dales, England (Figure 1(a)). There are well developed and connected Type 1 and Type 2 gully systems (Li et al, 2018a): Type 1 dissection usually occurs on the flatter interfluve areas where peat is usually 1.5-2.0 m in depth on slopes less than 5° (Bower, 1960a), with gullies frequently branching and intersecting as an intricate dendritic network; Type 2 dissection dominates on steeper slopes (exceeding 5°), with a system of sparsely branched drainage gullies incised through the peat and aligned nearly parallel to each other. There are well developed and connected Type 1 and Type 2 gully systems (Li et al, 2018a): Type 1 dissection usually occurs on the flatter interfluve areas where peat is usually 1.5-2.0 m in depth on slopes less than 5° (Bower, 1960a), with gullies frequently branching and intersecting as an intricate dendritic network; Type 2 dissection dominates on steeper slopes (exceeding 5°), with a system of sparsely branched drainage gullies incised through the peat and aligned nearly parallel to each other.…”

“…The study area is a mini-catchment within Fleet Moss, with a large area of exposed bare peat actively eroding with sheet erosion and gullying. There are well developed and connected Type 1 and Type 2 gully systems (Li et al, 2018a): Type 1 dissection usually occurs on the flatter interfluve areas where peat is usually 1.5-2.0 m in depth on slopes less than 5° (Bower, 1960a), with gullies frequently branching and intersecting as an intricate dendritic network; Type 2 dissection dominates on steeper slopes (exceeding 5°), with a system of sparsely branched drainage gullies incised through the peat and aligned nearly parallel to each other. The vegetation is dominated primarily by Eriophorum vaginatum, Calluna vulgaris and Empetrum nigrum.…”