How sand dunes change and why it matters
hi everyone
lots of us love to spend time at the
coast
in fact last year 135
million days were spent as tourists on
our coastline and why not
it’s fantastic time to spend some time
with fantastic place sorry to spend some
time with friends and family
explore nature and get some exercise
however
our sand dunes are more than just a
tourist attraction they’re also a
fantastic defense
against coastal erosion and coastal
flooding protecting those communities
that live behind them a really good
example of this
is here at ancel beach just north of
liverpool
you can see here that this is a sanjin
that’s recently been eroded
so large waves combined with a high tide
has taken away the front of that dune
but it’s protected everything
that it’s behind it coastal sand dunes
are amazing and that this june will
actually
under normal conditions naturally repair
itself as well
so that sediment that’s currently stored
offshore will move onshore so towards
the land
during um small wave conditions it will
then dry out on the beach
and winds coming from the sea moving in
towards the land will blow that sediment
on towards the dunes and build them back
up again
our sand dunes are also a really
important economic and recreational
resource as well
if you think around the british isles
how many famous golf courses are
situated within our sun dunes
and if you go to somewhere like north
west ireland the vast majority
of recreation pitches are also in places
like county donegal
are situated on our sand dunes some
sanjins
are a tourist attraction in themselves
to jun de pilar here in france
attracts tens of thousands of people to
hike up to the top of it
and enjoy the scenery that’s around them
today however
we’re going to be mainly talking about
coastal dunes as an ecological resource
and this image from north morphodufferen
in north wales
really demonstrates why within this one
picture
you can see a myriad of habitats you can
see bare sand
which is almost like a desert dry and
easily moves around
you can see grassland which offers
different patches of shade and different
habitats within it
you can see shrubs which will grow under
mature trees and then you can see these
ponds
these are called genus slacks these are
ephemeral ponds that fill up with
rainwater
in winter and spring and then dry out
over the summer
and this diverse range of habitats also
supports a diverse range of species
everything from lizards cycles such as
sand lizards amphibians
called narjac toads which live in those
gin slacks as well as over 400 vascular
plants
and loads and loads of invertebrates
such as solitary bees which burrow into
those loose bits of sand
however this diverse image of asanjin is
decreasing in the united kingdom and
throughout the world
increasingly our sanjins are becoming
greener and greener and those patches of
bear sand and june slack are
disappearing
so why is that what’s going on well
first of all
we’re living in a changing climate our
world is becoming generally well
certainly in northwest europe
warmer and wetter and that increases the
amount of growing time in the growing
season
that these plants can then colonize and
take over those patches of bear sand
throughout the world over the last 70
years as well it’s generally becoming
less windy
and so there’s less opportunity for that
bare sand to be blowing around creating
that disturbance in the habitat
which creates that vast mosaic of
habitats that we saw in the last image
within the uk there’s also been a
catastrophic decline in grazing pressure
in the last 70 years
so for several centuries things like
rabbits have
eaten and grazed within the water thin
sand dunes and taken away lots of the
young vegetation along a diversity
of vegetation in the diversity of
landscape to exist within it
however with the introduction of max
mitosis in the 1950s
that robert that rabbit that rabbit
population
catastrophically declined and that
grazing pressure was removed from the
dunes
some areas of the uk also suffer from
invasive and exotic species either
escaping
from gardens and taking over this
engines or being planted within them to
try and stabilize them and stop them
from moving around
so what’s been the result of this
dramatic change in bear sand
in our sand dunes throughout the united
kingdom over the last 70 years
well lots of our rare plants have
invertebrates are declined
and some species have been lost
completely
in the uk however there is a legal
obligation to try and
maintain those rare species or increase
them and some would argue
there’s also a moral obligation to do
that as well
one way we’re doing that is to try and
artificially recreate
those disturbances that happen so one of
the ways is by taking
large machinery and scraping some of
that top layer of vegetation off
allowing winds to come in pick up that
sand and blow it elsewhere
another measure is what they’ve done
here in uber war in an anglesey
is actually cut and punch a hole through
the forging and allow
nutrient per sediment so to be blown in
from the beach
through this gap in the dunes and then
blew into the hinterland behind it as
you can see here
and that creates as you can see a bit
more diversity in the habitat that’s
there
there are however some locations that
are bucking this global trend
they’re literally going against it where
across the world we’ve seen a general
greening of dunes
there are some locations in the united
kingdom that these
mobile dunes are actually still
increasing and growing and it’s these
exceptions to the rule
that are really really interesting to us
as scientists what’s going on at these
locations
that gym mobility is not only still
happening but it’s actually increasing
with this information can we then help
those land managers and help those
interventions be more sustainable
and help create that diversity within
these landscapes
so the first thing we have to do is
actually quantify the amount of sand
that’s in these students
and as you can imagine it’s just not
feasible to go around and survey
every single bare patch of sand with an
asanjin
so instead we’ve taken to the skies
initially through satellite data
we’ve analyzed them onto bear sand more
recently
using aerial photography that’s been
flown from planes and now
the state of the art using unmanned
aerial vehicles as drones
we fly these at only four or five
minutes above the gin we get a really
high resolution image of how much bear
sand and habitat is within it
so once we’ve identified where that bear
sand is the next job as a scientist
is to try and understand what is driving
it what environmental factors are
causing that bear sand to happen in that
location
and the first thing that we’re looking
at is wind speeds at the location
and it’s not feasible to go out with
anemometers and cover the entire
landscape with
with measuring devices so instead we’re
numerically modeling that wind speed
so we’re using a bit of software called
computational fluid dynamics
and this is most commonly used to design
formula one cars and jet planes
and we’re using it to model wind flow
virgins however what it does give us
is a really high resolution of wind
speed and turbulence
a centimeter scale and a really high
accuracy
across an entire landscape so we have
that one layer
another layer that we use is elevation
and slope
and we put all these different layers
together and then try to
statistically predict where those
locations of mobile sound are
we can identify those environmental
drivers that help bear sand and mobile
sound occur
then hopefully we can spread that
information and give it to the land
managers who make in those interventions
the hope is that they can make them in
strategic places where they’re most
likely to be sustainable
and they’re not going to have to be
topped up and frequently gone back to
and removed nut vegetation
overall we hope to create a landscape
that is a benefit to people can be
utilized by people and enjoyed by people
but in which also nature can thrive and
survive
thank you very much