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