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Can re-wilding the uplands help to prevent flooding in the lowlands?

The recent flooding in the north of England has prompted calls for better flood defences and river dredging. But these measures are unlikely to work by themselves, especially with the increased likelihood of extreme weather events in the coming years. A new approach is needed that considers whole catchment management – starting with the source of rivers in upland areas. Upland landscapes have been drastically transformed from their original forest state, and this has affected river flow in lowland areas. The reduced water-holding capacity of uplands makes for fast release of water, contributing to flooding downstream. Therefore, restoring upland landscapes is an essential part of good flood management, and could also help to revitalise upland communities.

To make an effective management plan for upland areas, we need to understand the history of these evocative landscapes. The uplands are dynamic cultural landscapes that have responded to human management for millennia; choosing restoration targets therefore needs to blend social as well as ecological considerations. Fossil pollen and charcoal, found in peat bogs and other wetlands, shows that tree cover has declined over time, driven by increased grazing and burning. Extensive forest clearance began in the Iron Age and intensified in mediaeval times as monasteries expanded grazing and wool production. Grazing and fires were used to keep pastures free of encroaching trees, and over the centuries, deep layers of peat developed, creating unique moorland soils. Over time, a system of transhumant pastoralism developed, in which cattle and sheep were moved between winter and summer grazing areas, allowing lowland pastures to rest in the summer months. The annual migration was an important part of pastoral society and ecology; townships grew up around the summer grazing areas, and mosaic landscapes developed with forest fragments, woodpastures, and moorlands. Veteran pine and oak trees can still be found on abandoned woodpastures, themselves now highly valued as the enduring sentinels of a lost way of life (Figure 1).

Image credit: Abandoned woodpasture by Kate Holl and Mike Smith. Used with permission via science direct.
Figure 1: Abandoned woodpasture from Holl, K., and M. Smith. 2007. Scottish upland forests: History lessons for the future. Forest Ecology and Management 249:45-53. Used with permission.

Cultivation, overgrazing, burning, the harvesting of wood for construction, and bark stripping for use in the leather industry also contributed to ongoing woodland clearance (Dodgshon and Olsson 2006). From the late 1700s, many hill farms were abandoned or forcibly cleared to make way for more extensive forms of sheep farming, and traditional transhumant systems began to erode (Holden et al. 2007, Davies 2008); (Dodgshon and Olsson 2006). By the mid-19th century, enclosed sheep farms were dominant, due to high prices for wool, mutton, and lamb, and the introduction of new, hardier breeds of sheep that could spend more of the year in the hills. Continued grazing, managed burning to rejuvenate heather plants, as well as soil erosion and acidification prevented tree regeneration (Dogshon 2006).

Overgrazing continued in the twentieth century, encouraged by guaranteed prices for livestock. Subsidies for upland drainage and afforestation projects further degraded upland landscapes and contributed to soil acidification Holden et al. 2007). Since industrialisation, changes in nitrogen, and sulphur deposition have altered soil properties, affecting ecological processes like peat-building and heather maturation. By 2003, 86% of moorland SSSI’s (Sites of Special Scientific Interest) were in poor conditions due to overgrazing and inappropriate burning (RSPB 2007).

A consequence of overgrazing and woodland clearance in the uplands has been soil erosion and reduced water holding capacity, leading to faster release of water from upland areas and increased flood risk in the lowlands. At the same time, channelization of rivers in the lowlands and urban developments on floodplains has reduced the capacity of lowland areas to absorb water and buffer waterflow. As well as woodland restoration, other measures, such as blocking gullies and drains, help to restore peatland and wetland habitats, reducing erosion and contributing to water and carbon storage (Reed et al. 2009). In valleys the restoration of fluvial meanders and riparian corridors can enhance biodiversity and connectivity, and increase the buffering capacity of rivers. Abandoned farms in the most remote upland areas provide opportunities for re-wilding with large mammals.

The socioeconomic landscape of the uplands is now in flux and there are new opportunities for changing upland management. New Common Agricultural Policy (CAP) subsidies are decoupled from stock production and instead reward compliance with good farming practices and a range of environmental standards. This has led to a decline in stock numbers, and a move away from hill farming to more productive areas in valley bottoms. At the same time, afforestation schemes have declined and there is a move towards planting native woodlands, which supply a range of products and ecosystem services (Reed et al. 2009). A new ‘Environmental Stewardship Scheme’ subsidises farmers for developing and maintaining agro-environmental plans that conserve biodiversity and provide ecosystem services like ground water recharge, flood prevention, carbon storage and recreation. In addition, the Environmentally Sensitive Areas schemes (ESA) supplements upland farmers’ incomes and helps to safeguard landscapes through good farming practices, such as limiting stocking rates and reinstating traditional husbandry that reduces upland stocking levels over the winter (Reed et al. 2009).

The future of the uplands is therefore open and involves a negotiation between what is environmentally and culturally desirable, ecologically feasible, and economically realistic. The overall aim for uplands today is not to reconstruct an arbitrary point in the past but to provide flexible, resilient, and richly diverse upland landscapes with woodland and moorland elements that sustain a wide variety of livelihoods, ecosystem services, and heritage values (Peterken 1996, Tipping et al. 1999, Brown 2010). Such systems could help to ameliorate problems of extreme flooding in the lowlands, by restoring water-holding capacity and evening out river flow.

Featured image credit: nature Bach lake river by re1kojote. Public domain via Pixabay.

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