OK. I think we have been waiting long enough.......
The answer is;
1.How many ‘layers’ are there in woodland?
The are four recognised layers to a woodland.
2. What are they called?
Ground
Field
Shrub/scrub
Tree/Canopy
3. Why are some missing?
Not all woodland have the four layers. Some woodlands may not be old enough to have had the time to establish all of them.
If you have big deer population in your woodland, they can and do eat the ‘bottom’ out of the wood. Like must chains, if one link is missing the whole systems starts to malfunction.
One of the biggest reason’s is the simply that the bottom layers receive no light from above and the reason for this is because the canopy has closed and become over grown so shading out the plants below – no light- no growth- dead!
Don’t forget, the whole of the woodland is governed by light, to much or to little cause’s a whole lot of problems or advantages......depending on what you want.
Also bear in mind, that each would is profoundly unique to any other. If you look at a beech wood, it may be many centuries old but it may only own one layer and that is the canopy. As a rule, nothing grows under beech.......beech cast’s such deep shade.
Maybe you are not in a woodland, perhaps you are in a plantation, again plantations throw deep shade.
Overstood hazel coppice is a strange one. Hazel itself, lives in the shrub layer but if left is turns into the canopy layer but if coppice will revert back to the shrub layer.
The field layer fairs a lot better as this layer is very shade tolerant. The mosses being prevalent, again, do not take anything for granted in a woodland as they do have a habit of catching you out. Mosses like all year round moisture and they are quite often missing in our lowlands woods and are only found hanging on to fallen wood. I have worked one wood that had no moss at all, nowhere.
This woodland was used in WW11 as a ammunition and fuel damp for the RAF and the US 101 st Airborne. Gliders flew from here to take Pegasus Bridge on D-Day. During the war they sprayed the woodland floor with a chemical that no one knows off and since then, nothing has ever grown on it.
Incidentally, We drove 4 hours to go to Duxford air museum to commemorate D-Day and I had one of the greatest pleasure in my life, as I shook hands with one of the Glider Pilots who flew from the airfield to Pegasus bridge on D-Day. This man brought tears to my eyes. Very emotional feeling.
4. Why do some woodlands have the lot?
All four layers will have a strong presence in a well managed coppice because the coppice cycle works so well because we are managing the light over a seven years cycle. It is opened and then it is closed. In the open period, light, hence warmth ( by the way, the woodland soil temp is about 15 degrees at the moment) reaches the floor and the dormant seeds that have been sitting quite for many years, waiting for warmth of which they need to instigate their germination.
Bramble is good example to use for this.
Also the answer to this question, is the opposite to question 3.
5. Can we re establish the missing layers?
Yes and no.
If you have a beech wood, you aren’t going to have much luck, as we said earlier, it doesn’t allow any light to reach the woodland floor. But in a normal mixed broadleaved wood, you can control the layers by controlling the light. Of course, this can take more than a life time to achieve, but that is the very nature of woodland work.
6. Does it matter if there are missing?
Dam right!
If the shrub layer is missing, I have no job!
Remember, that within each layer, lives different species of insects, plants, fungi, birds and mammals. All depending upon each other for food, pollination, camouflage and shelter, if one of these layers is missing, then you will be missing it’s associated wildlife. You will have a less diverse ecosystem. The knock on effect is pretty endless.
Anything to do with such a diverse ecosystem as our woodlands ( they are the most diverse ecosystem outside the tropics) needs to be studied at great depths and with a great deal of understanding.........I watch them everyday and they never fail to astound me.
