Tuesday, 14 July 2015

Bracken overload

At this time of year, the bracken is growing to a monstrous size, in some places becoming impassable without a struggle, making  parts of the wood no go areas. There seems to be much more of it in OC1 (South 15 acres)   where it is most insistent in the few small areas that  have been clear felled of birch and/or Scots Pine. This  has allowed the sun in, and the bracken to completely  take over from early June to late September.

During the winter of  20011 a new glade was created in the Scots Pine adjacent to the Pond.The spot was chosen because the pine was quite sparse , so not much felling was involved. Unfortunately, once  the pines were removed, the bracken immediately rushed in, growing taller each year until now it is impossible to get through. 

The felled pine trees in the new glade, cut to lengths

The resulting sea of bracken

A path, bracken bashed from the clearing to the cabin . Recently I disturbed a large grass snake while it  basked in the sun on the path, and watched as it  slithered away into the bracken.

There doesn't seem to be so much bracken in OC2 (North 15 acres) and this seems to be not always connected to light and shade levels, for example, the 'deer scallop' , the open area which joins up with a new track leading off from the car park, is very sunny , and covered with bluebells in May, followed by soft grasses and ferns in the summer, but there is very little bracken.We don't know why this is so. I suppose we have to live with bracken that takes over during the summer before it dies back in September, as long as the paths, tracks, Rides,  and other areas of high use such as around the Cabin, are kept clear - regular walking about and driving  in these places will keep it down anyway. There is not much bracken in the wetter areas of the wood.

Bracken  deprives other species of light, makes a deep litter of dead rust brown leaves in the Autumn and  produces chemicals that inhibit seed germination and seedling growth , thus  preventing regeneration.  Bluebells seem most able to survive it, primarily because they emerge before the bracken gets going,  though we've seen  increased bluebell cover where the bracken has been removed so it doesn't smother the bluebell bulbs in heaps of dead leaves.. Mosses seem able to flourish underneath it, but very little else. Historically, bracken was harvested for a number of uses, but since this ceased it has spread unchecked, particularly in dry acid soil, of which much of Old Copse is composed.  It spreads by underground rhizomes or on bare ground by spores.

Sarah, bracken bashing in the 'car park clearing', made in 2010
There are a few suggestions for
bracken control.  Treating with herbicide ,  except we don't want to use herbicides in the wood. Regular rolling - with what, we''re not clear;  and other manual methods such as frequent pulling, breaking, and top whipping  all of which can be done quite easily, it's not hard work, and children enjoy  it , especially if a small bribe is on offer - the problem is that it's time consuming. Some people advise getting a few pigs in -  but as well as rooting out the bracken and brambles (good), they'll eat the bluebell bulbs (not good).                                                                                                                                                            
 The first small clearing we made in the birch in 2010  was developing a nice line in foxgloves and   bluebells primarily because of our strict bracken control. However, recent monitoring indicates  reduced flowering . This would appear to be because control has been neglected in the clearing because the two of us simply do not have the time to do it as regularly as it needs. But it might also be because of the increased amount of grass which is growing taller each year and might add to the struggle that some ground flora will have.

It's not all bad news though. Bracken supports 40 species of invertebrates, and for 27 of these it forms an important part of their diet. 11 are found only on bracken. It is used as cover by birds , and shelters reptiles and mammals. But, like another 'thug'  - bramble, which  in moderation, also has its uses to wildlife, we don't want it at the expense of almost everything else. Biodiversity is proving harder to encourage than we originally thought.

 We plan to start some end of Summer mowing/strimming to see what difference this makes. This might help keep down the fast emerging brambles, which along with bracken gives us a double headache. Also, having learned from the clear felling episodes in OC1, we will pay close attention to light levels in any future felling project , and aim to keep a careful balance between light and shade,. Once the Scots Pine thin is completed, we'll do some replanting with broad leaves which, as they grow, will help to discourage rampant bracken growth .

Where the tractor and digger compressed and  turned over the ground during the cabin build last year, the bracken is making determined efforts to return to full strength, but it is easier to control around the cabin.. It's interesting to see what is coming up  in its stead. We haven't so far  identified all of the plants, and are hoping that the deer don't make a meal of  the new growth.