Sunday, 24 October 2010

Considerations when planting a new woodland

As the former owner of a forest tree nursery I have been asked this many times, there are no definitive answers to this question, the best guide that you have got is to look around your local area and see which species of trees are growing well and/or make up the most of the local woodland. This way you do not have to worry about your soil type or climate -nature has aready shown you what will do well.

natural regeneration of sweet chestnut less than 20 years after this pasture was abandoned. I thinned this area a year ago and removed about half of the less vigorous and poorly formed trees

Also you should have a clear goal in mind, are you planting for wildlife and conservation, or future firewood or timber production. Your main objective could be to screen yourself off from a neighbour or an ugly development, or it could be a combination of all these factors or many others.

Many people say plant willows, everyone knows that they grow quickly, but really what is the point unless you are a basket weaver or your land is a bog (you have very few other choices in this case), they are of generally speaking little timber, firewood or long term screening value.

I would imagine that cutting a large area of willow manually as a short rotation coppice for firewood could be mindnumbingly boring. (I find cutting hazel stools bad enough-they are a lot of work for not much wood). An endless supply of small round logs that are difficult to stack and burn away quickly on the fire. Volume production isn't everything when considering what species to plant. I am sure that these are great for totally mechanised woodchip production for biomass.

Poplars are also often advised, these are certainly quick with 2-3 meters per year possible with some of the newer clones. They have little firewood value but do have a timber value if they are grown and managed in the right way. I must say that a poplar plantation is about as interesting as the highly disliked conifer monocultures but without the winter shelter.

Another suggestion made by people who are just looking quick wood is the Foxglove tree (paulownia tormentosa) which can be grown to sawlog size in Europe in as little as 8 -15 years. This is a native of China and although its a rapidly growing tree it can also be very invasive. Recent advances in breeding have lead to clones being introduced that can resist temperatures of -15 celsius possibly even -20 celsius. As a wood it is lightweight being around half the weight of oak. It is also noted as being highly fire retardant, so perhaps best avoided as firewood! As a tree it is promoted as not subject to pest problems in Europe, there is a good reason for this-none of our native insect species can feed on it. Pollinating insects however do well as it produces very showy white/pink or purple flowers depending on the species.

After well over 30 years of looking at woodlands I have come to the conclusion that the best form of woodland establishment is to mimic the way that woodland normally colonises new ground. For example in my area any previously cultivated land that for whatever reason becomes abandoned is rapidly covered by blackberry, broom, silver birch, willow,aspen,alder and hazel.

Ok, you would be mad to want to plant blackberry and broom but it is easy to see that the birch and the others are colonising species (oak can also colonise grassland too if the conditions are right).

Oak natural regeneration at 5 years from germination. I'll keep the neighbouring broom bushes under control so that the oak is not crowded out

One the birch starts to gain a little height other tree species start to appear- oak,sweet chestnut, ash perhaps a scattered scots pine or douglas fir and finally beech. These grow better after the site conditions have been made more suitable for them by the colonising species. The colonisers are quick growing but generally short lived so that when they die they are replaced by the secondary species of tree that then go on to make the dominant trees over the longer term.

The problem is that everyone who plants trees wants it to look like a woodland as quickly as possible. It is my conclusion that you should plant a mix of colonisers planted for there quick growth and the other species that are going to make up the longer term which could at sometime in the future become a valuable asset.

7 year old self seeded scots pine growing together with sweet chestnut, beech and silver birch

This will however lead to future problems. It is likely that without management the quick growing pioneers will overtop and surpress or even kill the slower growing "crop" trees. So you need to be in there watching and managing your woodland, always keep in mind your long term goal(s) You cannot just let it do its own thing or your not going to get the result that you wanted.

Douglas fir that I planted 5 years ago inamongst my hardwoods-naturally regenerated sweet chestnut and ash and planted beech. As you can see I don't tend to plant in rows and prefer to plant in groups between the trees seedlings that arrive naturally. It gives a more natural appearance but does need managing regularly to prevent overcrowding problems.

It doesn't really matter because trees grow slowly don't they? Well they can but they don't have to. Everything that you do from even before you plant the trees influences how fast they will grow and develop. Think of your trees as you would the plants in your garden, if you neglect these and don't give them there optimum conditions they perform disappointingly. The same applies to your trees. I shall try to cover these issues in later posts.

Finally to the issue of conifers. To many people these are to be avoided like the plague but in my opinion they do have a valuable place in the woods. Firstly as an economic value, last year I felled 2 large douglas fir, 47 years old. They gave me wood to the value of over 800 euro's. Ok I had to fell the trees,extract them and get a mobile sawmill in to process them. But this is in only 47 years, if you grew an oak or beech you would usually need to double or triple that age to get something of a decent value.

At age 47 an oak can show great promise but not great financial value. I'm not saying lets plant only douglas - private forestry already does more than enough of this around here, but why not plant a handfull or a few dozen conifers inamongst your hardwoods? The birds like them for nesting and winter shelter. They are useful for screening and also add a bit of body to your young woodland during the winter months and can have a highly beneficial nursing effect on your broadleaves. Many species can be removed for Christmas trees. You can think of conifers as a temporary but beneficial addition to your woodland or leave a few for perpetuity like I do.

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