Ancient trees and woodland management at Hatfield Forest

Hatfield forest is an incredible survival of a landscape little changed from medieval times. Here under the flightpath of Stansted airport there are hundreds of trees that were growing during Shakespeare’s lifetime, coppice woodland, pollard trees, flower rich meadows, marsh and a history of land management little changed for 1000 years. 

Hatfield has a special meaning to me, I lived and worked on the forest for 3 1/2 years, we had no car at the time and I often didn’t leave this 1000 acre wonderland for weeks at a time. The woodland historian Professor Oliver Rackham felt Hatfield was so important he wrote a whole book about it called “The Last Forest“.

Today in common usage the word forest tends to be used to describe a large woodland and forestry is woodland management, in medieval times the meaning was different. The word forest is a Norman term and it did not necessarily mean woodland at all, it meant an area with special laws particularly regarding the rights of hunting and tree cutting. Most forests were areas of open ground particularly heathland sometimes with areas of woodland which provided cover for game. This was the case with Sherwood, the New Forest, Epping, Dartmoor and Exmoor, the Forest of the Peak and many more. These places provided the crown not only with a playground for hunting but a source of game and timber.

Hatfield is a small forest but a remarkable survival in that it is pretty much unchanged from the earliest descriptions and maps. A popular misconception is that woodlands disappear when cut down. This is not the case, British woodland trees if cut down will regrow from the same stump and at the same time as light hits the woodland floor seeds germinate creating a thicket of new growth. This is an area of woodland at Hatfield that I helped cut down 19 years ago.

 The thing that destroys woodlands is grazing animals which eat all the undergrowth, shoots from cut tree stumps and seedlings. For this reason in traditional woodland management woods were fenced against grazing livestock. The main product of woodlands was fuel wood and in the days before chain saws firewood was ideally small diameter. The woods would typically be cut once every ten years, the trees regrow from the same stump and in ten years each stump will produce maybe a dozen shoots, each the thickness of a mans wrist, perfect for cutting for firewood with an axe. The thin tops were all bundled into fagots for firing bread ovens, pottery kilns and such like. This system is called coppicing, here are some old coppice stools I cut 18 years ago.

Hatfield still has a large wild population of fallow dear and when the coppices are cut it is always important to keep the deer off. When I was there we used to cut very large areas which minimised the effect of browsing and also piled heaps of hawthorn brash over the stumps to protect the regrowth. I see they have recently got some mobile deer fence panels to temporarily fence newly cut areas which seems an excellent idea. In medieval times each coppice area was surrounded by a ditch and bank or woodbank which was topped by a fence made from the cut material. The fence only had to stay deer proof for maybe 4 years by which time the new growth was above grazing height. This is a woodbank seperating the wood on the left from the open grassland or “wood pasture” on the right.

Wood pasture is another very special element of the medieval forest. Here grazing animals and trees have to coexist, if the trees were cut at ground level the livestock would kill them so the medieval woodcutter cut the tree above the head height of the livestock. The tree would regrow and end up with a short fat stem and multiple branches which again could be cut on rotation every ten to twenty years. Much is still unknown about the practices, did they cut in winter as we tend to do today? or in late summer so that as well as wood the branches would be valuable for fodder, leaves and bark would be eaten.

These trees are called pollards and the continual cutting greatly extends their lifespan, they tend to be hollow and the rotten centre provides home to a huge range of invertebrates (Hatfield is in the top ten sites in the UK for dead wood related invertebrates) The old bark is also habitat for rare lichens. A tree has to cover it’s entire surface area each year with a skin of new cells. This means it is always growing fatter. If it has a big crown producing lots of food the growth rings will be wider, if it has just been pollarded and has a tiny crown the growth rings get very thin. So a very broad tree that has spent most of it’s life with a very tiny crown can be very old indeed. Around 120 years ago pollarding became very unpopular and the pollards were allowed to grow naturally. Here are a few of the 800 or so pollards of 8 different species that survive at Hatfield.

This one is field maple Acer campestre and at over 3 feet diameter amongst the largest in the country.

And this oak is the biggest on the forest, hidden deep in the southern scrubs no one knows it is there unless they have been shown where it is. No trick photography here, I do look tiny because the tree is that big.

When I was at Hatfield we were struggling with the problem that these pollards now have huge crowns balanced on top of thin hollow cylindrical trunks and in high winds they can literally be torn apart. Also they were an aging population with no new pollards created in 300 years. We set about creating new pollards and also gently reducing some of the older ones to balance the crowns and reduce the risk of wind damage. This is an ash which I topped out, I remember as the limb hit the ground a dazed tawny owl few out of a hollow. A previous experiment in the 70’s involved repollarding a number of trees in one hit but this massive shock had resulted in many trees dying. The new management of just rebalancing the crown was not ideal since it encourages growth high up rather than low down but it bought time. If I was still there I would think this tree is ready for cutting again now.

And this are some of the new “maiden” pollards.

 There was still a big age gap between the old trees and the young and one of the more exciting things I was involved with whilst at Hatfield was trying to bridge that gap by cutting bigger trees. Cutting larger trees straight down to pollard height could kill them but we found by gradual reduction over a few years we got better results. This is a tall pollard made from a larger maiden tree which has regrown well and could now be reduced to it’s final pollard height just above the lower branches.

It didn’t always work, this ash died but still provided excellent dead wood habitat.

If you click to enlarge the photo you will see the amount of insect and woodpecker activity that has gone on here and there was also a hornets nest in the base. I only noticed as I looked down and saw dozens of then around my feet, thankfully I was stood just 18″ aside of the flight line.

And this is new woodpasture. The area was mainly hawthorn scrub with young maiden trees growing through, we cleared the scrub, pollarded the trees and 18 years grazing has done the rest.

There are lots of things to learn by revisiting places. This tanalised fence on top of a woodbank I know to be 45 years old, we were impressed when I worked there that it was 25 years old and still sound. I have also known tanalised fences that were rotten after 5 years, it would be nice to know how this treatment was different.

The good recorded history at Hatfield allows us to understand better what we are seeing and help date things that often folk can only guess at. This yew tree for instance most would think a yew this size would be ancient.

We know however that the earth bank that it is growing on is part of a dam built in the 1730s so the tree is less than 300 years old. Whilst the trees are fantastic at Hatfield the more closely you look the more you find, there are very high numbers of species of anything you care to study, bats, dragonflies, fungi. The grassland is very species rich too, I am not sure how well it shows in this photo but this grassland is covered in small mounds, they are ant hills created by trogladite yellow meadow ants Lasius flavus. The important thing about these is that they take many years to build an ant hill pushing grains soil up from underground, Whenever you see anthills like this in a meadow it tells you that it has not been ploughed or harrowed for many years and so is likely to be species rich.

Most visitors to Hatfield however just come top walk the dogs, run the kids and eat chips at the cafe.

And just yards from the cafe is one of the largest oaks in the country, it’s perfect proportions and high branching make it look smaller than it is. I once spent 2 days deadwooding this tree and even the lower branches feel a long way up. When folk next tell you how there are no big trees left in the UK any more show them this picture, this oak is far bigger than the biggest timber in any surviving building in the country.

9 Responses to Ancient trees and woodland management at Hatfield Forest

  1. Tico September 8, 2010 at 12:43 pm #

    Robin,This is a fantastic post. I've never understood the practice of coppicing and what pollards were. You have a great gift for explaining things.Thanks.

  2. Janice in GA September 8, 2010 at 3:08 pm #

    Your depth of knowledge and ability to explain what's going on really help me understand things better. I kinda knew what coppicing and pollarding meant, but seeing your pictures and reading your explanations really bring it to life for me.Many thanks for a great blog and great information!

  3. flyingshavings September 8, 2010 at 7:12 pm #

    This is an excellent post Robin. Many thanks. Wood is a massive continent with many highways and byways of fact, fiction, misunderstanding and enlightenment. I regard you as one of the reliable waymarkers – like one of the trees used to mark out the land, like the Laund Oak near my workshop which marks the division between the Forests of Knaresborough and Barden (of course you don't look quite as old as t'Laund – 800 yrs).

  4. Le Loup September 8, 2010 at 9:51 pm #

    Good post, I still do pollarding in Henry's Wood, Wychwood Forest.Regards.

  5. pfollansbee September 8, 2010 at 11:21 pm #

    Robinthanks for this & the previous post regarding trees, woodland, etc. Very nice to review that sort of material. Although I am far away, trees of Great Britain and their use & management is an important part of my studies; so it’s nice to get a fresh synopsis complete with the very clear photos. Historical timber use if often garbled; I hear several times a month about how there are no big trees in England any more! Nice work

  6. pegsandtails September 9, 2010 at 7:53 am #

    A joy to read the past few posts Robin. I am very surprised at your dating of that Yew. Could the ditch have been built around an existing tree. It's so huge!

  7. Jeff September 9, 2010 at 3:14 pm #

    Very informative and quite appreciated, Robin since pollarding and coppicing are virtually unknown practices here in the colonies.In fact, topping (pollarding) trees is very frowned upon here since it is known to promote disease and to weaken the structure of the tree particularly when subject to windy conditions. I wonder if the British practice is less harmful since it appears that the cuts are made rather frequently. Thus, the new, and structurally weak sucker growth is never allowed to get to a size where it would be as likely to be damaged in a storm. I also imagine that different species react differently, and that some are more favorable towards the practice. I do believe that Colonial Williamsburg has some pollarded American Sycamore trees.

  8. Robin Wood September 9, 2010 at 4:52 pm #

    Thanks for all the comments, glad the info was of interest. Traditional woodland management was my passion for many years. Having moved on to other things it is easy to forget that much of this stuff is not common knowledge.Peter there are probably more and bigger trees in Britain today than there have been any time in the last 1000 years, we just don't get out to the woods much and we don't cut our trees as often. We tend to import most of our timber and have been doing for many hundreds of years. My local sawmills all use French oak and it is 260 miles to Dover. Pegsandtails, the yew is on a very high bank 15 feet above the surrounding ground level so the dating is pretty secure, I posted the picture to show that size and age are complex. I once felled 2 ash both 10" diameter 100 feet apart. One was 30 yrs old the other 120. Like carrots in the garden some find the nutrient and thrive and some just hang in there.Jeff, you are right pollarding causes a potential weakness which becomes a problem as the branch grows big. It is common around the Mediterranean to grow pollard plane trees for shade (what US call sycamore) and they cut all the new growth every year. In London plane trees are sometimes topped high up (not really pollarding) this is a great way for tree surgeons to make money as it then needs doing every 10 years or the weak junctions fail as the branches get bigger.

  9. Jeff September 9, 2010 at 6:48 pm #

    "We tend to import most of our timber and have been doing for many hundreds of years."I sure wish that you would export more English Oak to the colonies!