By Mike Swan, GWCT Head of Education
6 minute read
Planting trees is very fashionable these days, and most people think it is good conservation practice. Aside from replacing what our ancestors felled, there is also a halo of virtue because of carbon capture and global warming. Like all such fashions, however, there are specific considerations that can make a big difference to how much good is being done.
Those who say that we are only restoring what our ancestors destroyed should take a long look at the pollen record; in previous interglacial periods there is little tree pollen. It is almost certainly the case that our post glacial history of dense woodland over most of the UK is man-made. As the ice retreated a growing human population killed most of the larger herbivores, allowing trees to colonise what would otherwise have been grassland. So, the concept that our country should be heavily wooded is a view based on just one phase of history, when humans were already having a major impact.
The importance of open country
Some of the most threatened species of wildlife that we still have in the UK inhabit open country, where tree planting would be the death knell. Alongside open country gamebirds, think lapwing, curlew, redshank, snipe, golden plover, skylark, corn bunting, yellowhammer and yellow wagtail, amongst many more.
Its also crucial to understand that tree planting can liberate soil carbon. Growing trees on carbon rich soils such as peatlands and long established pasture can shade out the plants that lock it up, allowing the carbon to escape, so that the balance becomes at best neutral, and very possibly negative. On top of that, planting on deep peat, and especially blanket bog, is pretty much doomed to failure. On nutrient poor soils like this, trees never flourish.
Woods where they are appropriate
So, where does this leave the shoot manager who wants to plant something more permanent than cover crop as a game habitat? Well, first off, if there are woods on your patch already, adding to that is likely to improve game holding without causing any problem for open country species. As well as helping you to hold and show your pheasants, linking up existing woods can help other woodland wildlife that may be teetering on the brink to gain a stronger foothold.
Please also think about scrub; this is one of our most neglected wildlife habitats, and yet it can support a huge range of species that are not at home either in big woods or open habitats. From the game point of view, well managed scrub with its little open suntraps between the bushes is likely to be much warmer, and more inviting for pheasants than a big dark wood, while redlegs will positively relish such a place.
Patches of hilltop scrub can replace cover crop as the focus for superb pheasant and partridge drives, without fundamentally changing the nature of the countryside. Unlike many crops, they will not break down towards the end of the season, and so can be relied upon as drives right up to 1st February. On the other hand, proper woods in the same places can become cold and open at ground level once they pass the thicket stage, losing their value for game compared to scrub.
What to plant
Much to my embarrassment, some of my predecessors in the GWCT advisory service seemed preoccupied with ignoring the value of our native trees and shrubs, while searching for easier alternatives from oversees, and promoting them as a panacea. Japanese Evergreen Honeysuckle (Lonicera nitida) is a classic example. Yes, it is a very shade tolerant shrub, and no, deer and hares don’t like it, so you can plant it without protection. But, given a few decades it can form dense cold thickets that are a game and wildlife desert, so I would always avoid it.
So, what should we put in? Well, these days I try to stick to native species, looking for locally produced stock of proper local provenance. If we do this, we minimise the risk of importing disease, and avoid any issues of genetic dilution when our plants mature and start to exchange pollen with the natives. In large measure following this advice also means that we will choose species that suit the local soil.
If I am planting a proper wood, I would always include oak in the choices. There may be a long wait for acorns, but when they come, pheasants love them. Many people fail to realise that there are two species to choose from. Pedunculate oak (Quercus robor) is perhaps the more familiar, producing majestic mature trees and favouring deep clay soils. Its name refers to the fact that its acorns have stalks, whereas those of the sessile oak (Q. petrea) do not. This species has a more western and upland distribution, doing well on thinner soils, so it is the one to choose for sandier situations.
Other woodland trees that are on my menu, depending on soil type, include field maple, wild cherry, common alder, and native willows, plus the odd chestnut. Ash would once have been high on the list, but since ash dieback has taken hold, it seems pointless to include it and hope. Beech, hornbeam and sycamore cast deep shade that suppresses ground cover, so I prefer to leave them out. At the lower level, and down into the shrub and scrub layer, I would add crab apple, holly, hazel, hawthorn, native privet and dogwood.
Please remember that even in a mature wood, open sunny areas, wide rides and scrub patches make for better pheasant and woodcock habitat, so please include these in the planting, along with an outer hedge to keep out the wind.
I would also always advise anyone who is planting a permanent habitat of this sort to take professional advice. The GWCT advisory team have been helping shoot managers to plan and design new woods and spinneys for many decades, and set against the cost of planting, and the impact on the shoot if it does not go well, the fees are modest.
Weed control
Aside from lack of protection, the other major cause of failure by new trees and shrubs is weed competition. Grass can strangle young transplants, so please do not skimp on herbicide treatment. Mowing is a mistake as root competition from mown grass is worse than if it is left rank. Also, cutting around trees has a habit of inducing what the forester calls “Sheffield Blight”, where the sickle cuts down the sapling along with the weeds. In the modern mechanised world, “strimmer blight” involves ring barking the tree with similarly disastrous results.
From Victorian times onwards, game managers have planted conservation friendly woods, to the benefit of our countryside and its wildlife. Today we continue with that rich heritage, but successful planting needs thought, care and planning. There must also be a commitment to ongoing management to get the best results.
Tree protection
If not protected, almost everything that you plant will be damaged by grazing animals. Rabbits, hares and deer between them can destroy a plantation, and even if they do not, growth will be severely restricted.
In the late 1970s tree protection was revolutionised by Graham Tuley, whose corrugated plastic tubes were the first economically viable option to protect individual trees in a woodland and forestry context. From here on, there was no need for forestry fences and their restrictive effect on movement of game. With tubes to protect the trees, it was now easy to blank pheasants and partridges through young woods.
Tubes even had built in obsolescence; if they were not removed, they would photodegrade, and fall off anyway, so avoiding strangling the tree. But, now that we understand the issue of micro plastic pollution, plastic tubes must surely have a limited future.
Where they are still in place, we should collect them in when they are no longer needed, and re-use or recycle. Meanwhile, properly biodegradable alternatives, using wool or cardboard, are now being tested, and I’m sure we can look forward to an ongoing future for Graham Tuley’s basic concept, but without plastic.
Just one extra thought on all of this; please make sure that you use guards that are tall enough. Roe height ones at 1.2m offer larger deer like fallow and red a succulent salad at nose height when the sapling emerges from the top.