A great big thank you to the volunteers of the South Downs National Park seen here on Saturday cutting back the strip of blackthorn on the eastern border of Pheasant Field. We were lucky enough to have a visit from Butterfly Conservation’s Neil Hulme who helped us to devise a four-year rotational plan for blackthorn management in Pheasant Field particularly for the rare Brown Hairstreak butterfly (see our posts of 26th September 2016 and 8th January 2015 below). Pheasant Field is a great opportunity to form habitats for Brown Hairstreaks and we look forward to seeing more of them in the coming years.
This year’s coppicing is a 0.25ha site at the North West tip of the wood near Misty Bridge. This very distinctive coupe is dominated by nearly forty oaks, many of them in the region of 150 years old. There is a small central section where tall ash coppice has reached the canopy but in all other respects this is the part of Lag Wood that most resembles high oak forest. While it has many majestic trees, the variety of tree and plant species is the lowest in Lag Wood with oak making up over 80% of the volume. There is quite a lot of hazel, some crab apple and birch in the understorey and, in the ground layer, there is a scatter of wood anemone in spring and a thin carpet of enchanters’ nightshade in summer. Other flowers, such as sweet violet, honeysuckle and primrose are rare here. Species common elsewhere in Lag Wood such as bluebell, campion or bugle are absent.
The dense oak canopy is a problem for the oaks themselves. The youngest of them are around 40 or so years old and these are suffering from the lack of light below the canopy. Two have died in recent years and a third is showing signs of stress. Age diversity becomes a problem in many neglected woodlands and improving it is a key aim for us in Lag Wood. To achieve it we are coppicing ash and hazel but we will also be taking out at least two of the larger oaks at the north end of the coupe. This should provide the light and space required for oak to regenerate. Oak seedlings have started to grow in the coppice coupe we completed last year (see pic) and this is something we want to encourage as far as is realistically possible. To help protect these youngsters, and the re-growing coppices, we will be erecting a temporary deer fence at the end of the coppicing season.
A debris dam on the Lag Stream in Lag Wood. This dam is the first part of a series of measures proposed by the Ouse and Adur Rivers Trust on the water courses upstream of Spitalford Bridge in Lag Wood and Butchers Wood. The dam is not intended to block the stream, simply to slow down the rate of flow after heavy rainfall and help contribute towards natural flood prevention for Hassocks. It is constructed out of materials from the wood and is located where the stream naturally tends to form blockages. It is designed to allow aquatic life to pass through it, and it is hoped that it will add to the habitat diversity in this rare chalk stream. Two further debris dams have been constructed along one of our ditches to help slow down natural runoff from the wood during periods of exceptional rainfall. A huge thank you all the local volunteers who helped to construct them on a suitably rainy day last Thursday.
We are very grateful to local farmer Gary and his nephew Michael. Their flail mower, mechanical rakes and baler made possible what would have taken nearly thirty people to do in the traditional manner.
We are so pleased to see a Brown Hairstreak. In 2013 a single egg of this endangered butterfly species was found on a Blackthorn bush in Pheasant Field. Part of the vulnerability of these butterflies lies in the interactions of habitat that they require. Blackthorn is the sole food plant of Brown Hairstreak caterpillars and adult females only lay their eggs on younger specimens. Adult males and females congregate to mate on Ash trees and may be seen lower down nectaring on Fleabane, Hemp-Leaved Agrimony and Bramble. With our abundant Blackthorn and Ash, large stocks of Fleabane and Bramble (and a patch of Hemp Agrimony) we felt we could provide a good habitat for the Brown Hairstreak. In January 2015, with the help of the South Downs National Park volunteers, we started managing Blackthorn to provide space for the younger bushes preferred by the female butterflies whilst not allowing it to encroach too much on the main part of the meadow. Last Monday we were sitting in the meadow discussing progress with a ranger from the South Downs NP. We had seen no sign of Brown Hairstreaks. Less than an hour later a female Brown Hairstreak appeared a few feet from where we were. Was she making a point? Perhaps it was that your opinions on habitat depend on who you are. We see a complex interaction of woodland, marginal shrubs, meadow flowers and grasses. The Brown Hairstreak sees all these things as one habitat. We would tend to agree with them.
It is very sad to report the arrival of Chalara Ash Dieback in Lag Wood. The first symptoms are clearly visible, blackening leaves and shoots, often remaining attached to the stem and formerly healthy green stems turning brown and producing little or no leaf. The picture of a recently coppiced Ash stool (taken in early September) shows the classic early signs of the disease. Over time dark lesions will appear where leaves and shoots join larger stems. The disease is an airborne fungus Hymenoscyphus fraxineus (formerly known as Chalara fraxinea) and its tiny mushrooms might be seen on fallen ash twigs and leaves this autumn. Chalara Ash Dieback is known to claim around 90% of Ash trees exposed to it. Many of our recently coppiced Ash stools are already affected, and it is a melancholy sight to see the abundant regrowth we saw in June now blackening with disease in September. Some of our younger un-coppiced Ash trees are also showing signs of the disease.
There is no doubt that Chalara will have a significant impact on the character of Lag Wood. By volume around 35% of this wood is Ash, and Ash makes up nearly half of the canopy. But while it is hardly happy news, there are some glimmers of hope. Many older Ash trees may take several decades to succumb and, unlike Elm, the natural genetic variation in Ash will ensure that a few survive unscathed to create a new generation of resistant trees. The impact on wildlife will be comparatively slow and many of our other trees, Hornbeam, Field Maple, Alder and hopefully Oak, will take full advantage of the opportunities it brings. There is very little that can be done to halt the progress of the disease but we will be looking out for potentially resistant trees and adjusting our coppicing plans accordingly.
Finally, after many false starts, the mud dried out at the end of August and we were able to get a vehicle into our coppice coups and extract some wood. The picture shows the first of many small truck-loads of wood from the trees that we coppiced in March. We think that this is the first time since the 1950s that wood in any quantity has been harvested here.
Most of our wood is not of timber quality and will go for firewood. But we have discussed the development of short-rotation hazel for traditional fences and hurdles, and there might be opportunities to explore with other skilled crafts-people such as musical instrument makers who have expressed an interest, particularly in Alder and Field Maple. Our reasons for coppicing remain the same, to maintain and improve the biodiversity of Lag Wood. But our long term aim is to break-even on the costs of doing it. This goes at least some small way towards establishing that it is feasible to do so. A good day all round.