I am of the opinion that when replanting woods the seeds/trees should be sourced from as close to the place where the restocking is taking place as possible. Which is not what the ‘experts’ are now saying. I recently wrote to Living Woods magazine about this and my letter is in their latest edition.
If you would like to see the magazine and my thoughts then click …..http://www.pocketmags.com/viewmagazine.aspx?titleid=975&title=Living+Woods However they will charge you a small amount and look for the letters page.
So this is a copy of what I said.
I am concerned that the message that is being promoted at the moment is that we need to plant trees which have been sourced ‘from provenances 2-5 degrees south of their current location and from the same position relative to the Atlantic’. This is to account for climate change.
There are two problems with this approach. One is that it assumes that we know what the weather patterns and other environmental factors are going to be for the next few hundred years. The second problem is that even if our weather predictions are right, then will trees sourced from further south be suitable for all our conditions?
Let’s explore first the predictions for our future climate. I recall that only a few years ago it was called global warming. Now, just 10 years later it is called climate change because we now think that the globe is not going to get universally warmer. We do know that Britain is subject to the warming influence of the Gulf Stream and were it not for its influence we would be considerably colder. What we do not know is if the Gulf Stream is going to continue in its same pattern for the period of time it is going to take for an acorn planted today to reach the mature tree stage. There are suggestions that the melting of the artic ice could dramatically change its direction or even its existence at all which ironically would lower our average temperatures to something similar to Newfoundland. We also do not know what the atmosphere will be like in one or two hundred years time. Will carbon dioxide levels be much higher? What level of u.v. radiation will be penetrating? What pollutants might be about – there may well be some we have not even invented at present. Consider also what will be the value of woodland in the future? Will we still require timber? Possibly we will be able to grow oak planks in some form of tissue culture, and woods may become just a place for chilling out and wildlife.! I think it is once again a situation where man thinks he knows better than nature and we can manage the future confident in the knowledge that winters will be wetter, warmer and windier and summers will be drier and that situation will remain for the next two hundred years.
Now let’s turn our attention to sourcing seeds from further afield. First of all let us remind ourselves that locally sourced seeds will have a vast array of genetic traits which have developed over thousands of years that suit that species/ variety/race to its exact location. The soil type, soil structure, microclimate, local populations of fungi, bacteria, invertebrates and larger organisms such as the bird life will all be catered for and will be fine tuned to that particular location. The genotype will also be tuned in to the climate, but this is just one part of what the tree needs to survive. The seeds will also have a range of genes which help protect the species from diseases which have affected the population in the past. Furthermore within any gene pool there will be considerable variability, so that some seeds will be better able to cope with warmer conditions, some will be better able to cope with colder conditions and of course the majority will be best suited to the conditions which are prevalent at the moment. It is my belief that even if the predicted climate change occurs then we would still be better off planting locally sourced seeds because the local seed bank will cope better as it will have genes suitable for all the factors other than climate which the trees will have to cope with and some will also have genes suitable to deal with a changed climate, whatever that might be.
Importing seed from 2 to 5 degrees south of any location will bring a quite different gene pool. A few of the genes might be suitable for a new climate. Many of the genes will be those associated with immunity to pathogens from that area, but they may not have immunity to local diseases, or even a mild pathogen which our native trees have learnt to live with but a race from further south might find quite hard to cope with as it has never come up against it before. We all know how important the micro flora of the soil is to the growth of trees, and this will be quite different in other regions of the country or Europe so how will trees sourced from these areas cope with an alien micro flora?
‘A dog is not just for Christmas’ – an acorn is not just for our short span on earth. We do not know what conditions will be like in one hundred years time let alone what they will be like when the tree planted today finally dies so lets not think we know best and rush into an ill conceived solution.
Alan Waterman B. Sc. and local woodland owner.