The Grove Wood in Upton Country Park has, in most people’s memories, always had a ground covering of Laurel and Rhododendron Ponticum. Dating back to at least the early 1900’s these plants were brought from Asia and Southern Europe and introduced to provide shelter from wind, create cover through the woods and, not least, to provide a dazzling show of colour for a few weeks when the Rhododendron flowered.
Rhododendron and Laurel invade areas both through roots and branches touching the ground and via seed. Rhododendron seeds are tiny and wind dispersed; each flower head produces between three and seven thousand seeds, so a large bush is capable of producing several million seeds each year.
Over time these plants have spread through the majority of the woods and dominated the woodland structure. The dense evergreen leaves prevent light from penetrating through to the woodland floor and inhibit the growth of other vegetation growth, such as new tree saplings to regenerate the woods, ground cover such as bramble and nettles and of course any native flowering plants such as bluebells, foxgloves or daffodils.
Without these native plants the insects, mammals and birds that depend on them in turn begin to be forced out of the woodland as they search for food or nesting sites elsewhere.
The leaves of the Laurel and Rhododendron are very acidic and give off toxic chemicals which means they are unpalatable to most species, including insects when feeding on buds and new growth, or deer browsing the leaves. Over time this toxicity begins to alter the condition of the soil, making it even more difficult for native plants and trees to establish and create new growth.
Once these species have been removed and eradicated the toxic soil layer still remains. Where this has built up over a number of years the resulting thick mat prevents natural regeneration. This layer can be removed where practical, or left to naturally return to a more balanced soil type that will allow native plants to grow. For this reason re-planting with new saplings is not advisable and the woods need plenty of time to recover.
The work was undertaken with the tractor and flail, which mulches the vegetation as it progresses through the woods; this is much quicker than cutting with chainsaws and either chipping or removing the arisings. The flail also removes part of the stumps and root systems meaning there will be less re-growth over the next couple of years.
Tree surgeons then went in to remove any dangerous wood from the trees. The majority of trees that needed work were left as standing poles, providing good habitat for roosting bats and insects, and a useful food source for birds such as woodpeckers and nuthatches on the hunt for insects.
Branches or tree trunks that were felled have been left on the woodland floor rather than cleared away, as this provides further habitat for insects as they start to decompose. Only trees that are a hazard to the public were felled.