I often wonder what would happen to our landscape if humans suddenly vanished from the Earth. How would the landscape change? Given the amount of invasive plant species we have I’m sure a woodland would develop with a Rhododendron dominated mid-layer and riparian woodland with thick bank of Japanese Knotweed and Himalayan Balsam. That may be a little pessimistic of me and besides, given a thousand years or so, this would no doubt balance out, as nature takes on the challenge of creating a functioning, self balancing ecosystem.
This is one of the things that interests me most about nature, it’s ability to choose what is best for itself and sustain a course that eventually benefits such a wide range of biodiversity. It may not be apparent at first as, if left to its own devises, we would lose much loved habitats such as heathland and flower rich meadows, habitats that we praise for their abundance of biodiversity. They are however man made. Products of a system that once supported our needs for food, fuel and building materials.
Another thing that really interests me is paleoecology. This is the study of extinct ecosystems or the way they functioned in the past. This has influenced the new big buzz word at the moment doing the rounds in the ecological world. Rewilding. This is the process where you restore the key components of an ecosystem, the large herbivores, the predators that control them and then you simply step away and let nature take its course. As ecosystems once were, unspoiled and unaltered.
If you adhere to the Vera model (a theory created by Frans Vera), then what would happen is the creation of a fluid mosaic of woodland, punctuated by grassland, scrub and wetlands, continuously shifting with grazing pressures and storm events. Species would create holes in the woodland that would fill with wildflowers and grasses or heathland species. Over time successional change would cause the creation of scrub and then eventually high forest where the process would repeat. In some areas where grazing pressure is particularly high, the habitat would be maintained at certain stages. This has been shown in places such as the Oostvaardersplassen in the Netherlands, where a number of species where reintroduced and a policy of nonintervention was adopted.
But what could cause deforestation of large trees? I recently went to South Africa and witnessed a landscape of scrub, with large openings of grassland. Very few large trees persisted. This was the doings of Elephants. They can’t push over a large tree but they tear the bark off and cut off the supply of water and nutrients, flowing up and down the trunk, thereby killing the tree and dramatically changing the landscape.
But we don’t have elephants in the UK. Well we don’t now. We used to have several species of temperate elephant living in northern Europe. There is some really interesting evidence of this in every woodland in the UK, even possibly in your garden. Trees have adapted to the onslaught of large herbivores. Mid layer species such as Hazel and Blackthorn can regenerate from any point that it is broken. This is an adaptation from being repeatedly snapped. The latter of these species has thorns that are up to two inches long. Perhaps a little over the top for a few nibbling deer!
The point of this long ramble is to give an idea of what we are looking at with our woodland management. To the best of my ability I try and replicate a natural system, a tricky undertaking where you either have too much grazing or not enough and where you have to fill in the role of multiple species doing multiple jobs. I don’t really want to make the headlines for introducing large herbivores into a small reserve in an overcrowded south coast so when we go into an overgrown woodland we look at opening it up in a way where I sit there and think “what would an elephant do? What looks tasty?” Unfortunately no matter what I do, it will never be a truly natural system but it hopefully will bare some resemblance and therefore maintain all the benefits of a woodland that nature has created.
With that in mind we have spent a lot of time in Swanick recently, doing some large scale felling works. With many woodland sites across the country, at some point in the last hundred years or so, management stopped. This has led to the uniform growth of trees so that there is a thick canopy of predominately oak that is all at one level. Under this there may be some large, over-stood Hazel struggling on in the gloom of the understory. It looks dramatic but what we have had to do is come in and remove some of these larger Oaks. This isn’t something that we take lightly as I have a particular soft spot for Oaks and ones that are a hundred years plus, well they deserve some respect. It is however a wider picture thing and hopefully the benefits of a thinner woodland, one that resembles a more natural state, one that looks like it was engineered by nature, will have huge biological gains in the future.
We were lucky to have a great team with us last week. Over from the Isle of Wight we had Andy and the woodland apprentices.
Swanick Woods is within the the NATS (National Air Traffic Control) high security compound so working in there can be a bit tricky. Thankfully NATS are fully supportive of conservation works around Swanick and have been really helpful in getting us in and out of the site.
Arriving on Wednesday we were greeted by a lot of bramble and some very thick woodland.
After three hard days work we now have a nice sunny ride back and some much thinner woodland around the edges. Hopefully this will be a great area for butterflies. Purple Emperor are found in this part of the site.
As the site is completely fenced there is little deer browsing so a thick mid-layer has developed in some parts. It is however all of the same age, blocking out any light that makes it past the canopy of Oaks. Te result is that the only thing that grows on the forest floor is Ivy.
Acting like Elephants we came in, knocked a few of the larger trees out to great a few gaps in the canopy and then thinned throughout the Hazels, taking them out at random, leaving some young ones and some old ones to give a varying age structure. Standard coppicing procedure generally takes out an entire area to give a large light area called a coup. This has great benefits to wildflowers and invertebrates but what we are trying to achieve in this wood is a network of smaller patches throughout the woodland.
Very thick Birch and Ash regrowth in one area that had been clear felled perhaps 15 or twenty years ago. These pioneer species tend to be the first to colonise and with the appropriate grazing pressure they may have grown less uniformly.
We have now opened up the ride a bit more and thinned throughout, removing almost two thirds of the trees.
Removing some larger Oaks