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     Updated: 20/03/2008

Portsdown or Portsdown Hill?

A lot of people talk of the hill when they mean the down.  Portsdown Hill, in my opinion, is the A3 road which runs from Cosham up the slope of Portsdown to Widley!  In support I claim the wording on the Ordnance Survey Explorer map of the area.

Physical description.

Portsdown is an outlying ridge of chalk detached from the main Hampshire anticline with a syncline lying between them.  You can see this physical phenomena best from the top of the Crookhorn golf course looking north.  Because it has never been re-submerged after being forced upwards by continental drift in the distant past it is a geologically unique feature. The ridge lies on a 9 kilometre east to west line across the north of Portsea Island which it dominates.  The eastern end is in Bedhampton while the west end drops down to the Wallington area just north east of Fareham.

Along the top of the ridge on both slopes the top layer of soil is very thin but as you move down the slopes thicker soil deposits are found including to the south Coombe deposits and on the north Reading  Beds, London Clay and Bracklesham Beds.

 In ancient times the down would have been covered by woodland forming a southern edge of the Forest of Bere.  Thousands of years ago in Neolithic times the clearance of the woodland to make space for crops or domestic animals began and later timber would have been extracted - if there was any left on the down.  Once cleared and in use for grazing, notably by sheep, and from Norman times having a significant population of rabbits, the down would be covered by a short fine downland turf.  The intensive grazing also affected the productivity of the soil which became nutrient-impoverished.

Flora and Fauna

The sheep have gone, there are only a few rabbits left in a few discrete areas and deer appear only very occasionally.  But where the grass remains close cropped the spectrum of flora and fauna is superb.  Sadly much of the area is now covered by scrub which, while it may help some birds and insects it, is inimical to true downland species.  The Portsdown Countryside Service financed by Portsmouth City Council and the Portsdown Conservation Volunteers are engaged in an ongoing battle to reverse the capture of the down by scrub.  If you look at old pictures, often reproduced in books in the book shops about old Portsmouth, you will see pictures taken as recently as the 1960s with the down almost bare of scrub.  Now in a few areas progress is being made in its removal but we will never beat it all and that is not what we want to do.  We aim for a mosaic with a variety of habitats, including scrub of various ages and heights and including some woodland along the bottom of the south slope.  In 2004 we acquired machinery with aid from English nature and Onyx ENTRUST that has enabled a much more rapid clearance and maintenance of cleared areas on all but the steepest slopes. On the northern slope we will do what we can to improve the existing hedges etc. but this is a relatively low priority.

Birds.

Portsdown is not a bird hot spot but there is much to please the careful seeker/listener.  In March 2008 there is a very regular buzzard over the central area and kestrels are sorting out which fort to nest on.

Throughout the year you will find the common range of 'garden birds' all along the hill and sometimes stonechats which used to frequent  the top of the Paulsgrove chalk pit and Portchester Common.

In the spring migrants arrive and the scrub areas support blackcaps, chiffchaff,  a few willow warblers and a significant number of common whitethroat.  Lesser whitethroat are also present but much much harder to detect.  When I first came to Portsmouth Cuckoos were common but in the last few years they have been very scarce on the down.  Yellowhammers breed but they have not been common since 2000.  In 2007 they seem to have had a good year.

Owls are about.  Tawnies breed around Christchurch and these and little owls are sometimes seen round the forts.

Possibly the fields and woods north of the hill are better bird hunting areas.  Here you can find all 3 sorts of woodpecker and scarcer species like marsh tits.  It is also worth watching here for buzzards which now breed in this area and migrating birds also pass over the down particularly in the autumn.  Other raptors that pass over the hill include kestrels  and sparrowhawks all the time and occasionally hobby, red kite and peregrine.  

Plants

This is probably the most significant element in the fauna and flora of the down although the diversity of chalk downland plants inevitably leads to a group of insects being present directly related to the plants.  Through the spring and summer there is a very rich and changing tapestry of colour, mainly yellow and white, to enjoy as you walk on the down.  Much of this has been obscured by scrub but see the Portsdown Conservation Volunteers page for information on efforts to hold or reverse the spread of scrub.

Orchids are perhaps the most dramatic of the flowers and we have through the year a succession of common spotted, pyramidal and bee orchids in abundance.  A  small population of fly orchids does well in a private location.  In August (possibly late July) autumn ladies tresses are doing well with growing populations in the areas grazed and /or protected from mowing with a fairly short grass sward.

Rock Rose and horse shoe vetch are responding to efforts to improve their sites and its interesting that a possible result of this has been chalkhill blue spreading from the main site.

Bastard Toadflax is nationally scarce but there are a quite a few plants to be found on the hill including some on the short grass right in front of the viewpoint car park just east of the George.  Even though this is a very accessible site its hard to find the tiny white flowers partly because other tiny white flowered plants like squinancywort and fairy flax enjoy the same very short turf habitat.  So does lesser centaury  and it was a joy to find some of this in the same spot in the summer of 2000.

In 2003 we were all surprised by a rarity which baffled even the experts called in to try and identify it.  Eventually it has been identified as sickle medic.  This is an example of the sort of surprise that awaits the careful observant walker on Portsdown but in 2007 it was not showing many flowering stems...  In 2005 one of our volunteers found a strange broomrape in the red barn estate at Portchester which after much tooing and froing was identified as a variety of ivy broomrape.  It is doing very well in 2007.

In 2006 and two new flowers appeared - common valerian in compartment 10 and dropwort in 9.  Both are present in 2007 with the former doing well but the dropwort showing 1 pathetic flower spike.

There are myriad other lovely flowers to see, often forming a very attractive carpet or tapestry among the longer grasses.

Butterflies

Chalk downland species are well represented with marbled white, chalkhill, common and small blues all appearing at appropriate times of the year.  Some species are increasing in numbers e.g. wall brown, green hairstreak. 

When migrants, like red admirals and painted ladies, arrive from the continent Portsdown is one of the places they appear fairly early.  We also tend to get clouded yellow most years and this year(2003) they have been moderately plentiful as they have everywhere else.

Fungi

The down is not a great place for fungi but keep your eyes open in the autumn. Coriolus versicolor is fairly common on old wood stumps, and  yellow brain, a morel, and an the earth star (geastrum triplex) have been found.

Compartment numbers

A rough guide is as follows:

Compartment 1:  Immediately east of Portchester Common below a field of grain and a set aside field.  The eastern boundary is a straight line down the slope from the Driving test centre.
Compartment 2:  This obviously starts at the west on the boundary of Cmpt 1 and extends east to a fance at the edge of the Paulsgrove chalk pit..
Compartment 3: This is all the thin strip of down above the Paulsgrove chalk pit.
Compartment 4:  This large compartment spreads form the chalk pit to a fence down the slope just west of the car park & burger van at the roundabout at the top of Southwick Hill.
Compartment 5:  This lies between Compartment 4 and a fence down the slop just below the roundabout.
Compartment 6:  The triangular area of land adjoining Southwick (hospital) hill.

Compartment 7:   Another triangular area between Southwick Hill and the edge of compartment 8.  This is the area that has been used extensively by motor bikes.
Compartment 8:  A slightly smaller compartment below the western end of Fort Widley.
Compartment 9:  The large compartment below the eastern end of Fort Widley.
Compartment 10:   The compartment below the burger van near the Churchillian.

Grazing

For a few years now the hill has been grazed in the winter in compartments that are fenced, mainly by cattle but in 1999 and 2000 a small herd of goats have been used.  More compartments are being fenced so that the Countryside Service can use this near ideal way of controlling grass length and scrub on more of the hill.

Grazing does bring problems - partly because we are so close to the Paulsgrove & Wymering estates

Two pictures taken on 16th March 2005.  The first is of a calf born the previous evening, and the second of the first crossing of Southwick Hill Road by grazing cattle.   This was the culmination of a lot of work fencing adjacent compartments, building the holding pens and acquiring the 'crossing gates'.

You can help.  Obviously the first thing is for you to be careful in animal areas yourself.  Enjoy their presence by all means but do not disturb them.  IF you ever see anything untoward like sick or disturbed animals, dogs or children attacking the animals or broken fences then let us know.  Phone the police on 0845 045 45 45; me (John) on 9222 1361 or 07970 902108, or Richard on 9238 9623 or 07958 353107, or.