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  • Writer's pictureSim Elliott

Heyshott, Ambersham & Graffam Commons; Sussex Lowland Heath and Climate Change. 10.07.23

North West Sussex, just north of the South Downs, has an area of lowland Wealden heathlands (all called commons). Theses heaths are on the Folkestone Beds of the Lower Greensand; this is an area very different to the South Downs chalk downland and the High Weald ghyll woodland of Sussex; these heaths are geologically, biologically and historically fascinating. The Serpent Trail is a long distance path linking these heathlands, see South Downs Walks: The Serpent Trail. I walked part of this trail, going through Heyshott, Ambersham & Graffam Commons. Heathlands are now rarer than rainforest and one of our most threatened habitats, covering only 1% (1,595 hectares) of the South Downs National Park. ... 80% of {Lowland Heath] has been lost since the early 1800s, often through neglect and tree planting on previously open areas. Explore the Serpent Trail - South Downs National Park Authority

I reached these commons by getting the train to Chichester from Brighton (55 minute, 2 trains an hour) and then the 60 bus from Chichester to Cocking, just south of Midhurst (35 minutes, 2 busses an hour) 60 Bus Route & Timetable: Chichester - Midhurst | Stagecoach (

From Cocking, I walked through the chalk planation of Hoe Copse to Heyshott Green. I walked north through an old Drovers Way to join the Serpent Way. I then followed the Serpent Way through Heyshott Common, Ambersham Common and Graffham Common. From Graffham I walked through Selham, on country lanes, to Halfway Bridge. This is road walking with no pavement or verge, so care needs to be taken; although there was very little traffic on the lanes. From Halfway Bridge I caught the 1 bus to Midhurst 1 Bus Route & Timetable: Worthing - Midhurst | Stagecoach ( (once an hour, 6 minute journey), and then took the 60 bus to Chichester and the train to Brighton

All sections of text in italics are quotations, sources sited.

The photographs in this post are presented chronologically (in the order in which I saw things)

I am only an amateur naturalist; thus all identifications are provisional; if you note a mistake in identification please feel free to tell me. If you want to contact me about any aspect of this blog, email me at simeon[underscore]elliott[at]gmail[dot]com.

... Passing through purple heather, green woods and golden valleys, simply follow the Serpent Trail way marker discs to explore some of the most breath-taking countryside in the South East.

On the [Serpent]Trail you will see the beautiful and internationally rare lowland heath habitat, ... It is based upon the sandy rocks and soils from which its name derives and has characteristic habitats of heathland, woodland, acid grassland and acid bogs. Explore the Serpent Trail - South Downs National Park Authority

The Lower Greensand: The Folkstone Beds. From the Hampshire border eastwards to Washington, the Folkestone Sand outcrop forms a belt 1.0 to 1.5 km broad. It consists of a series of small undulating or sloping plateaux often capped at about 200 feet above mean sea level (c.60m) by a thick layer of flint pebbles, the plateau gravel, deposited here as part of a prehistoric river flood-plain. ...

The Folkestone Beds are a coarse, ferruginous sand containing beds of ironstone or even sandstone locally. In earlier times they seem to have been forested, probably with open Oak-Lime-Hazel wood, but clearance began locally (as at Iping Common) at least by Mesolithic times, and by the close of the Bronze Age, nearly all of it seems to have been cleared of forest: it was comparatively easy for early man to clear and cultivate on these light soils, while heavier substrates (such as the Gault clay) seem to have retained woodland in many places up to the present day. Early clearance seems to have been for pasture rather than arable; in Bronze Age times, many burial mounds or tumuli were erected on this sandy belt and many can still be seen.

Deterioration through leaching, and perhaps overgrazing of the deforested soils, seems to have led to the formation of the type of soil profile known as a Podsol. Francis Rose, The Habitats and Vegetation of Sussex, p.12

Climate change and heathland.

Walking round these commons I saw much dead heather. I had never been to these heathlands before so I don't know if the extent of dead heather is typical of these commons. However, when I walked around Iping and Stedham commons a few weeks ago I saw much more dead heather than had seen the year before (2022) and I also saw a reduction in the number of Siler Studded Blues at Iping (these butterflies are not extant at Heyshott, Amblesham and Graffham) and Iping for whom Heather is an important nectar source and caterpillar food, see Flowering plants, Butterflies & Birds; Drought & Reduced Abundance. Iping & Stedham Commons.16.06.23

In older literature describing these heathlands e.g. Habitats and Vegetation of Sussex Paperback, 1995, by Francis Rose Much richer in species are the wet-heath areas where the the water table is near or above the surface in winter; these occur on terraces, above seems of clay on gentle slopes where water seeps to the surface or bordering valley bogs. p. 13. I found the extent of bog and wet heath on these commons was much less than that which is described in Rose.

I saw very little Cross-leaved Heath, Erics teralix, which was described as abundant in wetter areas of these heaths in Rose, 1995. And Bracken was much more common than Bell Heather, Erica cinerea Common Heather Calluna vulgaris. These features are described as possible impacts of climate change in volume 17 (Lowland heathland Climate Change Sensitivity: Medium) of Natural England's Climate Change Adaptation Manual Evidence to support nature conservation in a changing climate

Of course my observations are only anecdotal, and I have only visited these heaths once, so are not objective data; but I think it is reasonable to conclude that the effects of climate change predicted by Nature England.

Moreover habitat loss and global warming interact in complex ways in relation to biodiversity loss: Habitat loss and fragmentation affect sensitive species and ecosystem functions. The nature of the surrounding area will condition the quality of the heathland remnants by, for example, propagule pressure from invasive species. The dominant ericoid shrubs can be out-competed by vigorous perennial grasses with increased atmospheric nitrogen deposition, although interactions with climate and management practices may either counteract or enhance this process. Grazing or periodic burning promotes heath loss but site-specific combined treatments maintain species diversity and community structure. Climate change alone moderately affects plant diversity, community structure and ecosystem functions. Combined with other factors, climatic changes will condition heath development, mainly with regard to key aspects such as seed set and seedling establishment, rare species occurrence and nutrient cycling in the soil. It is essential to address the effects of not only individual factors, but their interactions, together with land-use history, on heathland development and conservation in order to predict habitat response to future scenarios. Jaime Fagúndez, Heathlands confronting global change: drivers of biodiversity loss from past to future scenarios, Annals of Botany, Volume 111, Issue 2, February 2013, Pages 151–172, Heathlands confronting global change: drivers of biodiversity loss from past to future scenarios | Annals of Botany | Oxford Academic (

Table on page 137 Climate Change Adaptation Manual: Evidence to support nature conservation in a changing climate (Vol 17 Lowland heathland Climate Change Sensitivity: Medium)

I started my walk from Cocking, on the A286 (Chichester to Midhurst road) just south of Cocking Causeway and walked through Hoe Copse to Heyshott Green and joined the Serpent Trail just north of Heyshott Green. However the Serpent Trail intersects with the A286 at Cocking Causeway, so you could start there and miss out Hoe Copse

After I walked through Hoe Copse, I walked through an old drovers road through the chalk of the foot of the downs to Oatscroft - where I joined the Serpents Way. The drovers road is clad with Soft Shield Fern, Polystichum setiferum. The route is probably medieval; getting narrower and narrower as I walked north. Walking through these routes you can feel the history of the landscape of Sussex

Tall anomodon, Anomodon viticulous, with Common Pill Woodlouse, Armadillidium vulgare

Dark Mullein, Verbascum nigrum

Before reaching Hershott Common the Serpent Trail path skirts Goldball's (pine) Plantation

Heyshott Common

Bell Heather, Erica cinerea

Very dry Juniper Haircap; Polythrichum juniperinum

Red Admiral, Vanessa atalanta; I saw Red Admirals all across Sussex in the week of this walk; a mass migration from Europe.

Betony, Betonica officinalis

Planted Scots Pine

Curled Dock, Rumex crispus

Red streams, "stained" by the ferruginous nature of the greensand soil

Small Copper, Lycaena phlaeas

Pendulous Sedge, Carex pendula

Sphagnum sqarrosum, a moss of wet woodlands

Wood Dock, Rumex samguineus

Ambersham Common

SSSI citation: Ambersham Common is one of the best remaining sub-atlantic heathlands in West Sussex. It supports a rich assemblage of invertebrates, including three nationally rare species, and has a diverse community of breeding birds.

The Common has developed on leached podzolic soils over the Lower Greensand. The dry dwarf shrub heath which covers most of the site has been colonised in places by woodland, scrub or bracken Pteridium aquilinum. There is a small raised bog on Ambersham Common which grades into wet heath. The former bog in the south west of the site has degraded into acidic marshy grassland. Broadleaved woodland occupies the valleys of two small streams and also occurs along a disused railway in the north of the site.

The dry heath is dominated by heather Calluna vulgaris and bell heather Erica cinerea with dwarf gorse Ulex minor, petty whin Genista anglica and creeping willow Salix repens. A number of mosses and lichens are associated with the mature heather, including Dicranum spurium and Rhodobryum roseum (two mosses which are uncommon in the county) and the lichens Pycnobhelia papillaria and Cladonia strepsillis. In the areas of wet heath heather gives way to cross-leaved heath Erica tetralix and Sphagnum mosses, with deer-grass Trichophorum cespitosum and jointed rush Juncus articulatus.

The flora of the raised bog includes bog asphodel Narthecium ossifragum and common cotton-grass Eriophorum angustifolium with heather and bell heather forming drier hummocks over a permanently damp carpet of Sphagnum mosses. Hare’s-tail cotton-grass Eriophorum vaginatum and round-leaved sundew Drosera rotundifolia are locally frequent.

The area of acidic marshy grassland, formerly a valley bog, is dominated by purple moor grass Molinia caerulea, soft rush Juncus effusus and cross-leaved heath. This drying out process is largely the result of tree and scrub invasion. Bracken, gorse Ulex europaeus and birch scrub Betula species are widespread, and self-sown Scot’s pine Pinus sylvestris and Norway spruce Picea abies are found both as scattered trees and forming dense stands above the heath community.

Broadleaved woodland occurs around the periphery of the common. The majority is young birch and oak Quercus robur woodland although in the south east of the site mature oaks with some beeches Fagus sylvatica dominate in a more open woodland. Holly Ilex aquifolium is also present and the ground flora includes southern wood-rush Luzula forsteri, and moschatel Adoxa moschatellina as well as a number of ferns and bryophytes which are more commonly found in the west of Britain.

An area of acid carr, with alder Alnus glutinosa and Sphagnum, occurs as part of the same hydrological unit as Heyshott Common. The vegetation of this area is distinct from its surroundings, influenced by a chalk stream and supporting a base enriched flora. The ground flora contains good numbers of wild daffodils Narcissus pseudonarcissus and large amounts of the bryophyte Conocephalum conicum. This area also provides favourable conditions for a range of craneflies, including the nationally scarce Tipula livida, T. luna, T. helvola and Ula sylvatica.

The streams support a bankside vegetation which includes water mint Mentha aquatica, and opposite-leaved golden saxifrage Chrysosplenium oppositifolium. The tipping of chalk ballast along the disused railway line favours calcicole species such as cowslip Primula veris and yellow-wort Blackstonia perfoliata. A number of interesting invertebrates are also found here including the glow worm Lampyris noctiluca, the oil beetle Meloe proscarabaeus and two rare butterflies: the nationally declining pearl-bordered fritillary Boloria euphrosyne and the grayling Hipparchia semele. A calcicole vegetation is also found on Hoyle field which also supports a rich invertebrate fauna including the Red Data Book Ruby tailed wasp Chrysogona gracillima.

Ambersham Common is of national importance for its invertebrates, particularly Diptera (flies), Arachnids (spiders), Lepidoptera (butterflies and moths), Aculeate Hymenoptera (bees, wasps and ants) and Coleoptera (beetles). The Red Data Book Robber fly Entolmus rufibarbis, bee Heriades truncorum, fly Gymnosoma rotundatum and click beetle Dirhagus pygmaeus are present. The heathland also supports the nationally rare digger wasp Ectemnius borealis, (a species which is known from only three sites in Britain) and beetle Agrilus pannonicus the nationally scarce cranefly Tipula helvola, and many species which are rare or local in West Sussex including the bog bush cricket Metrioptera brachyptera and the wood grasshopper Omocestes rufipes (2 of 11 Orthoptera recorded at this site). A rich Lepidoptera fauna includes nationally uncommon butterfly species like the silver studded blue Plebejus argus and moths such as the red belted clearwing Synathedon myopaeformis and the clay fan foot Paracolax derivalis, as well as many others which are uncommon in the county.

The diverse breeding bird community includes three internationally important species listed on Annex 1 of the EU Birds Directive; nightjar Caprimulgus europaeus, woodlark Lullula arborea, and Dartford warbler Sylvia undata. Other bird species associated with the heathland habitat are stonechat, tree pipit, redstart, wood warbler and nightingale. Sand lizard Lacerta agilis, was introduced to the site in 1970 and is still breeding 1003996 (

Wet woodland (carr) with Soft Rush, Juncus effusus

Tufted Sedge, Carex elata

Gorse, Ulex europaeus, on either side of the Serpent Trail

Common Heather, Calluna vulgaris

Large White, Pieris brassicae

Birds-Foot, Ornithopus perpusillus

Tormentil, Potentilla erecta

Sharp-flowered Rush, Juncus acutiflorus

Lichens on a worked-wood footpath signpost. Usnea sp. possibly Usnea cornuta and Hypogymnia physodes

Soft Rush, Juncus effusus

Gorse, Ulex europaeus

Nomada sp. mining bee

Silver Y Moth, Autographa gamma. Probably the UK's most common immigrant moth. Silver Y | Butterfly Conservation (

A Holy Blue, Celastrina argiolus, nectaring on Bell Heather, Erica cinerea. Not a typical butterfly of lowland heath but their larvae can feed on gorse. Holly Blue | Butterfly Conservation (

Soft Rush, Juncus effusus

Neat Feather-Moss, Psuedoscleropodium purum

Red Admiral, Vanessa atalanta. There was a large influx of migratory Red Admirals in the week before my visit.

Bell Heather, Erica cinerea, with significant areas of dead heather (probably as a result of last year's drought)

Probably Reindeer Lichen, Cladonia portentosa, with a sprig of Bell Heath, Erica cinerea and possibly a sprig of Cross-leaved heath, Erica tetralix

Many-forked Cladoniam Cladonia furcata, with Broom Forkmoss, D cranum scoparium

Juvenile Stonechat (very noisy!) Saxicola rubicola

Oak Bracket, Pseudoinonotus dryadeus

Scots Pines, Pinus sylvestris

Neat Feather Moss, Pseusiscleropodium purum

Four-banded Longhorn Beetle, Leptura quadrifasciata

Gatekeeper, Pyronia tithonus

Buff-tailed Bumblebee, Bombus terrestris, on Bell Heather, Erica cinerea


Probably Common Powderhorn lichen, Cladonia Coniocreae. N.B. not in situ; this clump had fallen off a sandy bank; I placed on this nearby tree stump to better photograph it

Migrant Harwker, Ashna mixta, on gorse

Pincushion Moss, Leocobryum glaucum

Ringlet Aphantopus hyperantus on, probably, a Great Willow Herb

Comma, Polygonia c-album on Bracken, Pteridium aquilinum

Beautiful demoiselles, Calopteryx virgo, on the sides of a stream

Meadow Brown, Maniola jurtina, showing its leaf camouflage of its underwings

Graffham Common

Sussex Wildlife Trust: There are two sites on either side of the Graffham/Selham road that make up the reserve, which is part of the wider area that was once Graffham and Selham Commons.

We purchased the reserve during 2009/10 as a key link in the historic chain of Greensand Heaths and have been restoring the pine plantation back to heath and heath-pasture by pine and Rhododendron clearance and judicious scraping of the pine and Bracken litter layer.

Forestry drainage ditches were blocked to allow the wet heath to re-naturalise. It responded brilliantly and the heather is returning from the buried seedbank. Heathland birds too have returned to their ancestral territories. Please help protect them by keeping dogs to the paths.

The site has been fenced to reintroduce grazing back into this ancient landscape with gates to allow access to the many tracks. There is a horse riding permit scheme in operation with the neighbouring landowner otherwise riding is restricted to the bridleways only.

The Serpent Trail, a long distance route encompassing many of the Greensand Heaths in the area, runs through both parts of the reserve. If you have the energy, walk to the top of Gallows Hill to enjoy distant views of Petworth House and imagine darker times when those guilty of relatively minor crimes may have been hanged from the gallows.

There are a few old sand and ironstone quarries that supplied iron for the iron industry below in the weald. In more modern times the site was used for training Canadian soldiers in preparation for the D-Day landings. There are signs too of even older heritage with a string of Bronze Age burial mounds running along the ridge of the hill.

There are some ancient open-grown pines to be discovered around the reserve, probably over 150 years old, a sign of the Commons’ open heathland past. Fallen trees and old branches are left where they fall if safe to provide deadwood habitat.

There are plenty of wet seepages creating ideal habitat for Cross-leaved Heath, Purple Moor-grass and Hare’s-tail Cottongrass. Reserve profile | Sussex Wildlife Trust

Looking from Gallows Hill: Heathland retuning (e.g. Cross Leaved Heath, and Bell Heather) as Scots Pines felled and introduced drainage ditches blocked

Wood ant carrying a pine needle. There was a huge ant nest; "thatched" with pine needles

The ant was very perserver-ant when it got stuck with its pine needle.

Probably Heath Plait-Moss, Hypnum jutlandicum

Probably the most unusual of the 7 sculpture designs [for the Serpent Trail sculpture commissions], it is inspired by a map, drawn in 1625 showing the area as common land. Following a thorough tour of the area by a Sussex Wildlife Trust ranger the sculptor Graeme was shown the primitively drawn map of the area in the 17th Century, a tiny drawing of animals (almost appearing to be standing on top of one another).

Based on these drawings, the sculptor intended to create a replica of the drawing in carved stone. This sculpture reflects the former use of the site as grazing land but also refers to the rare map of the vicinity.

The piece is the largest of the sculptures standing at about 4ft tall and is carved from sandstone. Graffham Sheep Pig - South Downs National Park Authority

Possibly Cladonia casepoticia, Stubbly-stalked Cladonia

Possibly Cladonia digitala, Finger Cup Lichen

Possibly Sphagnum palustre, Blunt-leaved Bog-moss

Soft Rush, Juncus effusus

Common Whitethroat, Curruca communis

Three Moles Pub sign in Selham, on the Selham road back from Graffham, to the bus stop on the Midhurst to Petworth Road



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