I recently illustrated The Hidden Universe by Alexandre Antonelli.  This image of the zonation of a rocky shore ecosystem was one of the illustrations.

The timing of this illustration was an extraordinary stroke of luck.  Alex wanted a drawing that shows the different animals and seaweeds on rocky shores.  These plants and animals grow in different zones going up the shoreline.  The factors that cause these differences (also known as zonation) include physical forces such as salt levels, dehydration, physical damage from the waves.  There are also biological, or biotic factors at play, such as predation, competition for food, and competition for space.

How do I know?  Well, the week I started this project, I went on a fabulous weekend course.  All about Discovering life on rocky shores!  The course is hands on, so I took tons of photos and copious notes.  I sketched barnacle speciation, and shrieked with delight at Porcelain crabs.  I even saw my first blue-ray limpet.

My very poor photo of Blue-ray limpets

So when this illustration turned up, I was exceptionally well equipped.  Here’s the pencil rough, which I annotated so that it made a bit more sense.

Annotated rocky shores illustration

And here’s the final illustration.  Inking it up was an absolute joy, although it took a great deal longer than I would have liked!

Rocky shore line ecosystem zonation of species

In this blog, there are so many animals and plants discussed, that I’m taking the decision not to give every scientific name.  It’s just be a jumble of italicised Latin if I did. Apologies in advance to the purists among you!

Rocky shores: Splash zone

The very top of a shore is known as the splash zone.

Sea plantain Plantago maritima

The top zone has very little growing there except for the odd brave plant and Xanthora lichen.  you might get tough periwinkles, but the combination of dry and salty splashing is lethal to most organisms.

Plants that do survive here have amazing adaptations to allow them to tackle the salt.  They’re known as Halophytes, and I wrote a blog on them a while back.

Animal wise, shore flies visit, and slaters (relatives of woodlice) crawl about.  You get limpets, clinging on and anchoring themselves to the exact same spot for most of their lives.

Thrift Armeria maritima

Rocky shore Intertidal zone

Lower down, you’ve got the high tide or intertidal zone.  Animals and plants living here have to handle massive fluctuations in temperature and being out of water for 12 plus hours every day.  the crashing waves cause physical damage.  On the plus side, it’s so hard to survive here that there’s not a lot of competition.

Limpet (with mating barnacles on the side)

Chitons, whelks, winkles, and barnacles live here alongside hardy sea anemones and the toughest of all seaweeds, channelled wrack.

The whelks travel around when the tide is in, predating on mussels and other bivalves by drilling a hole through their shells and sucking out the meat.

Detail of the intertidal showing chitons, whelks, and a sea anemone

Rocky shore Mid tidal

This stretch is exposed for shorter times between tides.  There’s less wave action as a lot of the time the area is submerged.  You need to handle the changes in temperature and salt, but it’s a less extreme environment than the upper tidal or splash zone.

Mid tidal zone: Crab and Breadcrumb sponge with coral weed

More animals and plants live here.  Tons of shells like top-shells, barnacles, Perwinkles, and mussels, hang out amidst the seaweeds.   Different species of top shell and winkle favour different areas of the rocky shore.

Topshell

You can tell Periwinkle and Top-shell species apart by the shape of their operculum, the door at the bottom of their shells.  In top-shells this is invariably round.  Periwinkle operculum are tear shaped.

Detail of the mid tidal: Smooth periwinkle, Pin cushion starfish, mussels and bladderwrack

There are more sea anemones, and visiting shore crabs.  Sponges and starfish abound.

The drawback is that there are more animals surviving here, so there’s more competition for space.  Predation kicks in too, with the starfish feeding on mussels, flat periwinkles chewing seaweeds, and whelks feeding on bi-vales.  These are the biotic factors starting to kick in.

If space does become free, it’ll quickly be re-colonised.

Rocky shore Mid tidal: Barnacles

Barnacles have a good system; they can grow on top of other shellfish, and can extend their filtering arms from this substrate.  Barnacles are actually crustaceans, related to crabs and shrimp.

Free living barnacle larva land on intertidal rocks where their heads split and they establish themselves for a stationary life.  They filter food particles form the sea with their legs, which are adapted to work as sieves.

The problem with living on a shellfish is that if and when that shell dies, you get plunged to the floor where it’s every likely you will die.

Blue mussels Mytilus edulis with barnacles and bladder wrack

Rocky shore Mid tidal: Seaweeds

Seaweeds thriving in the mid-tidal zone are bladder-wrack, egg-wrack, toothed wrack, spiral wrack.  These grow at very specific heights along the shore, depending on their adaptations and tolerance to heat and dry conditions.

Bladderwrack Fucus versicolor

Rocky shore Lower tidal zone: Species

The lower tidal zone is altogether more comfortable.  Exposure to air, desiccation and the heat of the sun is far less frequent.  In fact, it only happens at low tides.  The waves are less problematic.

The bladder wracks give way to kelp.  Brown algal wracks are unpalatable to most animals.  In the UK, it’s only the Flat periwinkle that can handle eating it.  Oar weed and sugar kelp are an entirely different prospect and are clearly much easier to eat.  If you are lucky and look closely at low tide, you might see the tiny and stunning Blue-ray limpets grazing on a blade of Oar weed.

Edible crab, sea urchins, tube worms, star fish, brittle stars, more sea anemones, sea lemons and nudibranch hang out here, along with bivalves.

You also see Porcelain crab with their strange, squashed bodies.  Decorator crab, often festooned with bits of seaweed can be seen too.  Hermit crabs spend much of their time in this zone.

Lower tidal zone: Spiny Decorator crab, Sugar kelp, and blue ray limpets

Rocky shore Lower tidal zone: Biotic factors

Flip side? Biotic (rather than physical) factors. Far more predation.  And intense competition for space and things to eat.  Of course, with the physical factors being so much easier to handle, many organisms will migrate from this zone to the Mid tidal once the sea covers them.  There they can eat and predate on other species before retuning to the safety of the lower shore before the tide exposes them again.

Rocky shore Lower tidal zone

You even get sun-stars.

The biological factors such as predation and competition are extreme here.  Predation is fierce.  And competition for space in intense.  Yes, you don’t get smashed up by waves or dried out twelve hours a day.  But you do get eaten, and may well find it impossible to get a foothold in such a heavily populated zone.

Seahorse family groups

Some seahorse and pipefish species will spend time in this zone, although drying out is a real problem for them, so they tend to stay in the sub littoral.

Rocky shore: Sub littoral

Below the lower tidal zone is the sub littoral.  This area of the shore is never exposed to the air, not even at the lowest of tides.  It tends not to figure in rocky shore zonation as it’s more like shallow ocean than the shore.  Fish, crabs, lobster, kelp forests all abound here.

American lobster Homarus americanus

Complicating factors: Rockpools

Rockpools are vital for lots of these organisms, although they can suffer from enormous halinity and temperature fluctuations.  But to the aspiring rocky shore ecologist, rock pools can be confusing,  As they remain wet, you get organisms living there that should not be seen in the Upper tidal zone, or mid tidal areas of the beach.  Luckily, this is catered for by ecologists who examine rock pool life as a subset of the larger ecosystem.

The illustration above was done many years ago.  I now know that brittlestar (lower littoral specialists) and razor clams (sand living specialists) are unlikely to appear in any European rockpool.  You live and you learn.

Complicating factors: Exposure

It should also be remembered that the exposure of a rocky shoreline will have an enormous effect on the life there.  High exposure means it’s even harder to exist in the splash zone and Upper tidal.  More sheltered shores offer an easier existence.

Conclusion

This is truly a whistle-stop tour of the zonation of the rocky shoreline.  I have no doubt this blog is peppered with mistakes.  The FSC course tutor, John Archer Thompson probably has his head in his hands as he reads my version of his wonderful teaching.

As an excellent launch pad to much more on this subject, thanks to John, please check out his FSC rocky shore pages.

The post Rocky shore ecosystem illustration appeared first on Lizzie Harper.

Hawthorn Crataegus monogyna is one of the commonest trees in the British countryside, ranging from the far south to all but the most northern areas.  Although there are tons of mature hawthorn trees, both in woodland, fields, and uplands;  you also see it in hedges and scrub-land.

This tree provides one of my favourite sights in mid-winter.  A branch of hawthorn, still heavy with crimson berries, festooned with the pale ashy greys and greens of lichen is a thing of real beauty.

The trees can live for hundreds of years, often all that’s left of a long-vanished hedgerow.  Sometimes growing in harsh climates, their twisted and gnarled shapes make individual trees into landmarks.

Identification: Tree shape

Hawthorn trees are a modest 2 to 10 metres tall.  They have a straggly habit, often with emergent branches.  They often appear alone, perhaps on a limestone outcrop, or in the middle of a field of grazing sheep.

Having been used for centuries as a hedging plant, they frequently appear along field margins; both within hedges, and as remnants of hedgerows which have long since been neglected.

They’re easily identified by their spiny branches.

In winter, these can be confused with the branches of the Blackthorn Prunus spinosa which also bear spikes, although Blackthorn branches tend to look darker and more condensed than the hawthorn.  Also, the buds of Blackthorn grown on the spines themselves, whilst those of hawthorn emerge from the same point as the spines.

In summer and autumn, it’s hard to mistake a hawthorn for any other species.  The distinctive leaves, white flowers, and crimson berries make it a simple tree to identify.

Identification: Leaves

Hawthorn leaves start out as a vivid, pale, spring green.  They become tougher with age, ending up a dusty dark green colour.  Undersides of the leaves are paler.  The leaves are deeply divided, and toothed.

They’re about 6cm long and are often asymmetrical from the main rib.  Leaf shape is highly variable, even between the leaves on one branch.  Leaves turn yellow in autumn, before falling, leaving the berries behind.

Identification: Flowers

Flowers are white or pink, with five petals.  Anthers are a pinkish colour, turning to purplish or brown.  These flowers appear in May (hence the hawthorn’s other name) and form frothy masses in the hedgerows.  They grow in flat-topped inflorescences.

Their smell is sickly sweet, and flies love it.  Lots of people think it smells a bit unpleasant, and reminiscent of death.  This is no surprise, the chemical trimethylamine appear both in corpses and in hawthorn blossom.  In fact, people used to say that the flowers smelt very similar to the stench of bubonic plague.  This probably accounts for the custom of never bringing hawthorn inside the house.

Identification: Fruit

The berries of hawthorn are crimson, with yellow-orange flesh.  They’re referred to as “haws”.   Each one has one big pip in its centre.

The haw skin is shiny, and can be anything from vivid scarlet to an almost purplish deep crimson in older berries.  The fruits are a great source of vitamin C, and can be made into jelly.  More importantly, they provide vital nutrients for birds such as Redwing and Fieldfare, especially in the depths of winter.

Identification: Bark

Hawthorn bark is grey brown, with lots of small scales.  As hawthorn is so prevalent, you may well see it in hedges and waysides where the plant may not be large enough to have a proper identifiable tree-trunk.

Similar species

The Midland hawthorn Craetegus oxyacanthoides can easily be confused with the common hawthorn.  Differences are that the Common hawthorn has flowers with only one stigma, whereas the Midland hawthorn bears two.  And (logically), the Common hawthorn has only one seed per fruit, whereas the Midland hawthorn has two.  Berries of the latter are a brighter red, and more rounded.  Midland hawthorn leaves are rounder, and less deeply cut.

Habitats vary too.  Midland hawthorn is more of a tree than a hedge species, and is more tolerant of shade.  It likes chalky soils and is often found deep within shaded woodland.

Most garden cultivars are Midland, rather than Common hawthorn.

History: Folklore

Hawthorn is thick with foklore and superstition.

I have a friend from Ireland who was furious when I put a hawthorn log on the fire, and opined that the “wee folk” would come and get me.  He was dead serious, and from the look on his face that was NOT something one wanted to happen, so I took the log off again.

There are many tales of Fairy queens and supernatural beings living in hawthorn.  To damage any part of the tree, especially of a lone tree, could bring down their fury with disastrous and fatal results.

As mentioned above, the smell of hawthorn is similar to that of a corpse, so it was not brought into the house.  To do so would be to invite illness and death in.  There’s a possibility that this referred especially to the Midland hawthorn, which was more prevalent in the 16th – 18th centuries and has a stronger smell than the common species.

However, boughs of May (hawthorn) would be put outside houses, and decorated with wild flowers.  Having the flowers outside was clearly not seen as a bad thing.

Before the Gregorian calendar was introduced in 1752, the month of May arrived a little later than it does now.  The timing of the hawthorn blossoming probably dove-tailed more accurately with the start of the month, and with May day.  The old adage, “cas’t ne’er a clout [vest] til May be out” refers to the blossom, not the end of the month.

History: Religion

There are many associations with pre-Christian religions.  Westminster Abbey is built on a site called “Thorney island”, after a sacred grove of hawthorn that grew there.

It’s the sixth tree of the Celtic Ogham religion, associated with love, protection, and the heart.

The flowers, coming as they do in the full burst of spring, have long been associated with fertility.  The Hawthorn tree was the precursor of the maypole.  Blossoming occurred around the time of the Celtic festival of Beltane.  Weddings often occurred at the same time, and there are records of boughs of Hawthorn being put on the beds of newlyweds to bring love and fertility.  How this tallies with the fear of inviting illness and death is unclear.

On May day, the May queen and the Green man would unite and bless the land with fertility for the coming year.  Hawthorn blossom played an important part in the ceremony.

Interestingly, the link between faith and the hawthorn did not stop with the onset of Christianity.  The crown of thorns and Moses’s burning bush are said to be hawthorn.

There’s also the legend of the Holy thorn of Glastonbury, planted by Joseph of Aramathea, who owned Jesus’s tomb.  He was also Mary’s uncle, and happened to be travelling with a chalice of Jesus’s sweat, and one of Jesus’s blood.  As you do.  Stopping, he thrust his staff into the ground where it grew into the Glastonbury hawthorn.  This plant (not, of course, the original tree) still grows on Glastonbury tor, and flowers twice a year; once in May and once at Christmas.  What Joseph used to replace his lost staff is lost in the mists of time.

History: Food & Medicine

Hawthorn leaves were eaten, referred to as “bread and cheese”, and haws were used for jellies and wines.

Medicinally, it was used in tincture to aid a whole slew of complaints: heart-trouble, anxiety, and loss of appetite.  In traditional Chinese medicine, it’s used to lower blood pressure.

Uses

Hawthorn has been used since the 16th century, when land enclosure first took off, as a hedging plant.  It forms spiky, impenetrable barriers.

It’s wood is hard and pale, and is used for wood-turning, veneers, and tool handles.  It burns at high temperatures, so is good for fire-wood and charcoal.  As long as you’re not worried by the folklore and superstitions, that is…

Young leaves are edible, as are the berries.  Berries are best made into jams and ketchups as they may cause mild stomach upsets in some.  Buds are delicious in salads.

It is a wonderful plant for both birds and insects. Not only can birds feed off the berries in winter, but the growth habit and thickets makes a perfect space for building nests.

Long-tailed tits Aegithalos caudatus in amongst Blackberry and Hawthorn blossom

Over 300 species of insect rely on the Hawthorn.  Moths relying on it range from the Lappet moth Gastropacha quercifolia, which resembles dead oak leaves as an adult, to the Light Emerald Campaea margaritata.  The latter turns up in my house on late summer evenings, and is a beautiful animal.

Bees, flies, and wasps pollinate the flowers and rely on the nectar.

Small mammals such as the Dormouse also eat the berries, which are packed full of anti-oxidants.

Hazel dormouse Muscardinus avellanarius with berries, (but not Hawthorn berries)

Hawthorn is a popular and wise choice for those wanting to encourage wildlife to their gardens.

Threats

Increasingly, hedgerows are being grubbed up to allow access to more efficient farm machinery.  Old hedges, which need a lot of maintenance, ore often replaces with barbed wire.

Hawthorn can be affected by fire blight, gall mites, and aphids.  However, there’s no suggestion that the hawthorn is about to disappear from out landscape, which is a big relief.

Conclusion

Hawthorn is common, and easy to recognise.  It’s flowers and berries make it a well loved tree and shrub, and it’s usefulness in hedging can’t be underestimated.  Providing a haven for wildlife, a wealth of history and folklore, and bearing edible leaves and berries; there’s a whole lot to recommend this tree.  It’s also very beautiful.

Sources for this blog include websites of The Woodland Trust, Trees for life, the Green Parent, and Naturespot.

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