Oxfordshire Woodland Group

A visit was made to Shirburn Hill Box Woodlands and Chalk Grassland on Friday 04th July 2014 by members of The Chiltern Box Woodland Project, Chiltern Woodland Project, Chiltern Chalk Grassland Group and The Oxfordshire Woodland Group.

This box woodland is located on the eastern margins of Oxfordshire in The Chiltern Hills and is an open access SSSI site covering 160 acres comprising part of a coombe valley that provides stunning uniterrupted views from the Chiltern Hills out over the Vale of Aylesbury and White Horse as far as Didcot and Oxford.

The chalk grassland is incredibly rich in diverse floral species that co-exist with large ant hills which are estimated to be 100 - 130 years old.

The box woodland stretches in ribbon like fashion along the side of the valley forming a fairly distinct boundary between chalk grassland and box woodland.

Some small box seedlings were observed to be present close to the woodland edge with none of these managing to develop into full sized box trees probably because of continual browsing pressure by rabbits.

Occasionally a large box bush is present on the chalk grassland growing well away from the main box woodland on the downslope side of the woodland. Rabbits are damaging the anthills.

Inside the box woodland navigation between the box trees is very difficult due to the multi stem nature of the box and is especially dangerous due to a multitude of dead snag braches being present. The woodland floor is totally devoid of vegetation with only chalk and flint scree evident. No box seedlings are seen inside the box woodland however some evidence of suckering and growth from layering was seen. A visiting box expert was of the opinion that the current box trees are in the region of 130 years old with little commercial value (not big enough).

On the upslope side of the box woodland a quite different mix exists with widely spaced declining and dead juniper trees amongst large anthills which are providing a host site for the establishment of box seedlings and bushes.

Many of the sites where box bushes have become established are either found between anthills and more usually on former Juniper tree locations. One of these box bushes was inspected by John Pepper (no website). His family has been working in Northamptonshire making skittles from boxwood since 1924.

The upslope box bushes are forming localised clumps in a fairly irregular woodland edge fashion when compared with the very distinct downslope side boundary.

Group discussions took place to help determine whether or not the box woodland was naturally ocurring or had been planted. Examination of the evidence present in the landscape demonstrates that the box wood exists as a result of succession and box dominance (climax species) over chalk grassland and other scrub trees including hawthorn, cherry, birch, yew, sycamore, spindle and most importantly juniper.

Some discussion took place about possible intervention in the woodland both at its edges and the interior which has given rise to a conundrum over which habitat is more valuable to preserve or conserve in a dynamic landscape e.g. chalk grassland with anthills or dense box woodland or chalk grassland with scrub trees especially Juniper which is locally scarce.

Unless grazing regimes similar to those that existed over 100 years ago can be reintroduced then manual intervention might be needed to help maintain the current status quo.

Immediate actions could include localised removal of outcrops of box both on the up and downside of the box woodland and reintroduction and protection of juniper from damage due to rabbits & voles on the upslope side of the box woodland.

The vectors that have created this rare woodland scene are not completely known or understood but the very strong prevailing wind plays a large part in broadcasting box seed upwards along with the presence of preferred box establishment sites under juniper trees that were present on the upslope area.

Given that the box woodland is a ribbon woodland that is gradually increasing it's width especially on the upslope side of the woodland this might suggest that this box woodland might simply have become established from an overgrown hedge that was planted rather than naturally ocurring box bushes and trees.

It would be helpfull if a number of box stems across a defined section of the woodland were cut and examined to establish a ring count that could be used to produce an age profile across the box woodland. This might help confirm just how this woodland has developed and grown over time.

Ken Hume