Sand Dunes - Threats & Management

It is estimated that between 30-40% of dune systems in Great Britain have been lost over the last 100 or so years (Doody, 2001), potentially more now this statistic is over 20 years old. There are a number of pressures on sand dune systems, including afforestation, coastal development for urban and tourism purposes, disturbance, invasive species, and climate change (Jones et al, 2011; NatureScot, 2023). 

Key Threat: Climate Change
Changes in rainfall, temperature, weather patterns, and sea level due to climate change are impacting sand dunes in a number of ways. Sea level rise and extreme weather events are causing flooding of low-lying coastal areas, and increasing levels of erosion on beaches and dunes. Increases in drought or heavy rainfall events could influence moss, lichen, and plant assemblages, leading to a potential decline in species abundance and range (Jones et al, 2013). UK modelling indicates that by 2080 the water table in dune systems could drop by over 1m (Burden et al, 2020).
These factors also put increased pressure on sand dune systems to act as a sea-defence for inland infrastructure. However, sand dunes can face what is called 'coastal squeeze' where they are unable to be mobile due to artificial coastal defences on the inland side which stops them from shifting landwards (Jones et al, 2011).

Key Threat: Coastal Development
Coastal development, particularly housing and tourism infrastructure, can have huge negative impacts upon sand dune systems (Jones et al, 2011). Construction of infrastructure often requires stabilisation of sand dunes through artificial reinforcement and vegetation cover.

In addition, conservation designations such as Sites of Special Scientific Interest (SSSI) are sometimes not enough to provide protection to these habitats. A more recent example of the consequences of coastal development on sand dunes is the construction of Trump International Golf Links in 2012 at Menie (Balmedie) -  an area which was protected under Foveran Links SSSI. Despite opposition from local residents and campaigners, the Trump Organisation was granted planning permission and the golf course was constructed. This resulted in permanent habitat loss to the area (fig. 1). Foveran Links SSSI was partially de-notified as a SSSI in 2020 as it was deemed to "no longer have sufficient scientific interest to merit special protection" (Campbell, 2017; NatureScot, 2020).

Additional tourism and recreation to an area can also result in high visitor pressure, increasing sand dune erosion, vegetation loss, and habitat loss or fragmentation (Jones et al, 2011).

Key Threat: Invasive Non-Native Species (INNS)
INNS can also be an issue on sand dune systems, often growing in dense thick stands which prevents the growth of native plant species. Key INNS on sand dunes include sea buckthorn (Hippophae rhamnoides) (fig. 2) and pirri-pirri burr (Acaena novae-zelandiae) (NatureScot, 2023). 

For example, sea buckthorn has been introduced to some dune systems in an effort to control erosion through vegetation cover and sea buckthorn's extensive root systems. However the species can be very invasive and can alter the ecosystem structure of sand dune habitats. With the stabilisation of sand dunes, INNS can change plant assemblages present as plant species which are adapated to a mobile dune system will be outcompeted (Richards & Burningham, 2010). 

Management of Sand Dunes:
Sustainable management of sand dunes requires maintaining natural processes, and allowing sediment transport as part of dune dynamics (Jones et al, 2013). It is believed that sand dunes in Scotland are more resilient to erosion than those in England and Wales due to surrounding habitat mosaics and habitat connectivity. For example, nearby saltmarsh will aid in gathering sediment and reducing sediment transport in extreme weather events (Jones et al, 2013).

INNS can be managed by clearance - cutting or pulling out of the ground for example. However, the best method is to ensure INNS do not spread further through a site or between different sites. Biosecurity awareness such as cleaning boots, clothing, and pets before heading out to sand dunes or other habitats can prevent seeds, root sections, or burrs from being transported to new areas (NatureScot, 2023).