In addition to maintaining the early successional stages of dune vegetation,
where many of our obligate dune species reside, our invertebrate specialists advise
that up to 10 or 20 % bare sand is needed to maintain invertebrate interests. In
addition to open conditions, they also require warm substrates and a range of
habitats and habitat structures (Howe et al. 2010). At present we are far from
achieving this target, but the future focus will be on delivering greater mobility and
dynamism. However, such management can only be taken forward where it does
not conflict with the flood defense role of dune systems (Everard et al. 2010). This
means that efforts to increase mobility are likely to be concentrated on just a few
larger sites. Historically, there has been a tendency toward ‘‘patch management’’
rather than having a more integrated approach. There has also been a focus on
preventing both natural and man-induced erosion, which has no doubt aggravated
the problems we see today.
8.6.2 Techniques for Countering Stabilization
A range of options to counter stabilization is available. Small-scale, local disturbance can be promoted by increasing the levels of grazing pressure through
encouraging rabbits, or by the use of domestic stock such as cattle, sheep or
ponies. Domestic stock, particularly cattle, can also have a destabilizing influence
with their poaching activities. Heavy grazing pressure by domestic animals on
dunes on San Miguel Island, California, for example, resulted in severe destabilization (Erlandson et al. 2005).
Destabilization can also be generated through the reactivation of stabilized
blowouts. Studies (van Boxel et al. 1997) showed that for these to remain active the
area of destabilization needs to be in excess of 50 m
2 . Reactivations of blowouts
smaller than this tend to rapidly restabilize, but there is also now some evidence
(Arens and Geelen 2006) that even extensively destabilized areas (tens of hectares)
are likely to restabilize within a few decades and that new measures to reduce
stabilization may be required every 10 or 20 years (see Arens et al., this volume).
Larger scale, more invasive options include mechanical disturbance, such as
topsoil stripping and deep ploughing (Fig. 8.5). The latter, which inverts the soil
profile, burying any surface nutrients and unwanted seeds while exposing low
fertility subsoil, has been trialed at Talacre Warren in North Wales (Jones et al.
2010b). Soil cores prior to deep ploughing showed that the organic layer extended
to a depth of 25–40 cm with high organic matter content (4.7 %) at the surface.
After deep ploughing, the soil profile was successfully inverted with the organic
layer buried under 45 cm of pure mineral sand, and soil pH in the surface layers
was raised by around 0.5 pH unit, closer to that of the mineral sand from depth
(Fig. 8.6). These soil conditions should facilitate the establishment of typical dune
species and hinder the re-invasion of nitrophiles. Recent results show a degree of
success in providing conditions conducive to natural sand movement, and bare
sand cover remained at [70 % for the first 15 months. However, as studies in the
8 The Impact of Dune Stabilization
137
where many of our obligate dune species reside, our invertebrate specialists advise
that up to 10 or 20 % bare sand is needed to maintain invertebrate interests. In
addition to open conditions, they also require warm substrates and a range of
habitats and habitat structures (Howe et al. 2010). At present we are far from
achieving this target, but the future focus will be on delivering greater mobility and
dynamism. However, such management can only be taken forward where it does
not conflict with the flood defense role of dune systems (Everard et al. 2010). This
means that efforts to increase mobility are likely to be concentrated on just a few
larger sites. Historically, there has been a tendency toward ‘‘patch management’’
rather than having a more integrated approach. There has also been a focus on
preventing both natural and man-induced erosion, which has no doubt aggravated
the problems we see today.
8.6.2 Techniques for Countering Stabilization
A range of options to counter stabilization is available. Small-scale, local disturbance can be promoted by increasing the levels of grazing pressure through
encouraging rabbits, or by the use of domestic stock such as cattle, sheep or
ponies. Domestic stock, particularly cattle, can also have a destabilizing influence
with their poaching activities. Heavy grazing pressure by domestic animals on
dunes on San Miguel Island, California, for example, resulted in severe destabilization (Erlandson et al. 2005).
Destabilization can also be generated through the reactivation of stabilized
blowouts. Studies (van Boxel et al. 1997) showed that for these to remain active the
area of destabilization needs to be in excess of 50 m
2 . Reactivations of blowouts
smaller than this tend to rapidly restabilize, but there is also now some evidence
(Arens and Geelen 2006) that even extensively destabilized areas (tens of hectares)
are likely to restabilize within a few decades and that new measures to reduce
stabilization may be required every 10 or 20 years (see Arens et al., this volume).
Larger scale, more invasive options include mechanical disturbance, such as
topsoil stripping and deep ploughing (Fig. 8.5). The latter, which inverts the soil
profile, burying any surface nutrients and unwanted seeds while exposing low
fertility subsoil, has been trialed at Talacre Warren in North Wales (Jones et al.
2010b). Soil cores prior to deep ploughing showed that the organic layer extended
to a depth of 25–40 cm with high organic matter content (4.7 %) at the surface.
After deep ploughing, the soil profile was successfully inverted with the organic
layer buried under 45 cm of pure mineral sand, and soil pH in the surface layers
was raised by around 0.5 pH unit, closer to that of the mineral sand from depth
(Fig. 8.6). These soil conditions should facilitate the establishment of typical dune
species and hinder the re-invasion of nitrophiles. Recent results show a degree of
success in providing conditions conducive to natural sand movement, and bare
sand cover remained at [70 % for the first 15 months. However, as studies in the
8 The Impact of Dune Stabilization
137