Monday, 9 July 2018

Oaks - with an erratum

Part 1  Oaks around Byfield 

Several species of oak, Quercus species, occur in Britain including the evergreen Ilex or Holm Oak, Quercus ilex, to be seen in Byfield Pocket Park, and the Turkey Oak, Q. cerris, standing outside Byfield's village hall.

The Holm Oak or Ilex is evergreen. Byfield Pocket Park.
9 July, 2018
Some specimens of Red Oak, Q. rubra, a species from eastern North America, stand adjacent to Byfield's tennis courts.
The leaves of the Red Oak are very distinctive. Byfield playing fields.
9 July, 2018
I have seen the Red Oak with large, mature acorns at, for example, Stanford Hall, but in Byfield the acorns apparently fail to develop. (See erratum)
9 July, and the acorns of the Red Oak are still very small.
Turkey Oaks are very common and will hybridise with our Quercus robur. Though similar to our native oaks the timber is generally regarded as inferior. The leaf margins have up to ten lobes each side and these tend to come to a point.
The leaves of Turkey Oak are very distinctive.
Byfield Pocket Park. 9 July, 2018
The acorn cups bear long scales, pointing downwards and are instantly recognisable. At the time of writing those photographed in Byfield were some weeks short of maturity.
Turkey Oak. The seeds are held in a very distinctive cup.
Byfield. 9 July, 2018

These three are all to some extent naturalised here and there but we have only two species indisputably native to Britain.

Sessile Oak, Q. petraea, is not generally common in Northamptonshire, being a species of acid, well-drained soils and is the oak most often encountered in the north of Britain. It is frequent however on the mildly acidic soils of west Northamptonshire, particularly in woodlands around Preston Capes and I have also found it occurring around Newnham.

The commonest oak of the English lowlands is the Pedunculate Oak, Q. robur. Woodlands such as Salcey Forest, Yardley Chase and Rockingham Forest tend to be dominated by this species. The leaves have the wavy edge typical of our native oaks but usually have an extra pair of auricles (lobes) at the leaf base.
The leaves of Quercus robur in Byfield Pocket Park. 9 July, 2018
Part 2  Oaks in the landscape

Why do I bring up this topic of oaks? I am embarrassed to admit that, forty years ago, I was teaching that, prior to the introduction of farming, Britain's landscape was largely covered by 'closed canopy' forest, with oaks being the dominant trees. It was the received wisdom at the time, following the ideas of Sir Arthur Tansley, and up and down Britain thousands of teachers were probably spreading much the same message. But I - we - were almost certainly mistaken - on two counts. There is evidence to suggest that Small-leaved Lime, Tilia cordata, '...was once the commonest tree throughout lowland England' (Mabey, 1996) so I was wrong there. Furthermore, although there may have been extensive areas of closed canopy forest it would probably not have been oak-dominated. Oak seedlings need reasonably good light to flourish and the gloom of dense forest would not have suited them; seedlings would have perished or the acorns even have failed to germinate.

So, what would Britain's landscape have been like after the last ice had retreated at the end of the most recent - Devensian - glaciation and before humans began the inexorable program of change on a gigantic scale? This is the arguably the hottest topic currently exercising the minds of British naturalists and ecologists, and not just in Britain but across Europe and beyond. 

Evidence is accumulating to suggest that there would have been significant areas of an open nature, with the space created or at least maintained, by large herbivores - a megafauna. Some of the players, such as roe deer and red deer are still with us, but by and large the species involved have disappeared from the U.K. The gigantic aurochs, Bos primigenius, became extinct worldwide and the wild boar, Sus scrofa, was wiped out in Britain long ago, together with the omnivorous Brown Bear, Ursus arctos. On the continent the elk is greatly reduced in range and the Wisent, Bison bonasus, only survived thanks to a breeding program based on a handful of zoo animals. Attempts to recreate the aurochs by back-breeding from primitive cattle strains have only had partial success in the form of Heck cattle. The elk, Alces alces, and bison do not appear to have re-colonised Britain when the last glaciation came to an end.

Projects aimed at re-creating this landscape are being attempted in several places with perhaps the best known, and arguably the most successful so far, being at Knepp, in West Sussex, where 3,500 acres are being turned over to 'rewilding'. (Tree, 2018) Obviously with some animals extinct or unavailable it has been necessary to use 'proxy' animals, with English Longhorns standing in for aurochs (see below) and the extinct European wild horse, the Tarpan, being replaced by the Polish Konik. Lynx, wolves, wolverines? Not yet - but given time for the public and local farmers to come to terms with the idea, who knows?

One thing is certain: over the last decade teachers and lecturers will have been furiously revising their notes! With the wisdom of hindsight some objections to the 'closed canopy' idea are now glaringly obvious. Consider: was Stonehenge really constructed in the middle of a forest? The land there must have been largely open and yet at the time of its early phases the land would not have been cleared for farming. Some of the structures located in the immediate area date from around 8000 BC, Mesolithic times, thus predating farming. No: we are looking at land clearance by wild grazing and browsing animals, paralleled nowadays on the African savannah, and these large herbivores on the Salisbury Plain may be what originally attracted humans to the area.


I have now concluded that Byfield's 'Red Oaks' are Pin Oaks, Quercus palustris.


Mabey, Richard (1996) Flora Britannica  Chatto and Windus

Tree, Isabella, (2018) Wilding. The return of nature to an English farm  Picador

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