Some ten to fifteen million years ago, Iceland supported forests and woodlands of Redwoods (Sequoia), Magnolia and Sassafras.   The presence of such species suggests that at this time the climate was warm and temperate.  Later, in the Pliocene period, evidence from pollen studies, suggest that Pines, Larch, Birch and Alder had come to dominate; species that are associated with Boreal Forest - so the climate had cooled considerably. There then followed the glaciations of the Pleistocene (often simply referred to as the Ice Age) - a geological epoch which lasted from about 2,500,000 to 12,000 years ago.  Glaciers marched across the surface of the Earth, but retreated in the warmer inter-glacial periods. Read more...

As a species, we humans have only been present on the Earth for a ‘blink of the eye’ in geological terms.   The Earth is approximately some 4.6 billion years old. Geologists have divided up these years into a number of geological periods or epochs - from the Pre-cambrian (from the formation of the earth until about 540 million years ago) to the most recent - the Holocene, which started at the end of the last Ice Age - about 12,000 years ago. Modern Humans emerged out of Africa probably some 200,000 years ago, and since that time they have increased massively in number.   At the end of the C18th , there were probably about one billion people; now there are over seven billion. We have changed the Earth in many ways.   Read more...

How many trees are there in the world?  Four hundred billion was the figure often quoted; that is, until this month when a report in Nature has come up with a figure slightly in excess of three trillion.   This approximates to 420 trees for each person on the plant. How was this figures arrived at ?  Well, the team (an impressive array of scientists from Universities and research institutions all over the world) amassed data from national forest inventories, plus peer reviewed studies where forests and woodlands had been studied in detail; this information was then used to inform what was also being seen on satellite imagery. For the purposes of the study a tree was defined as "a plant with a woody stems larger than 10 cm at breast height".  Read more...

Yew woodland (in Southern England) tends to develop on the thin soils that form over chalk, often on the sides of dry valleys . They can be found along the North Downs, and in West Sussex on parts of the South Downs. Yew woodlands can also be found in the Cotswolds and in the Wye Valley (on limestone). In Ireland, there is a significant Yew wood near Killarney, again growing on top of limestone. Yew woodland may develop from chalk grassland, when grazing by sheep or rabbits is removed. With no grazing, Juniper and / or Hawthorn start to grow.  Then, between these, shade-tolerant Yew seedlings begin to grow.   Eventually, the Yew will overtake the Juniper / Hawthorn, and shade them out. The dead remains of juniper and hawthorn sometimes may be seen on the floor of a Yew woodland. Read more...

Birch is a pioneer species, that is often replaced by oak, beech or other species.   After the last Ice Age, birch moved in quickly as the glaciers receded.   Even now, after clearfell in almost any part of the country,  birch is usually the first to appear by natural regeneration (and can act as a nurse for planted oak etc.); some refer to it as the 'forester's weed'.    Birch woodland is generally “open” and the trees are often of a similar age and size. Birch regeneration is often respaced (thinned) with a clearing saw  (the resulting thinnings may be used for horse jumps - like the Grand National). However, birch woodland has mainly persisted (in the U.K.) where conditions are harsh and limit the growth of other species. Read more...

Beech woodland is native to Southern England and Wales (roughly, south of a line drawn from The Wash to the The Severn).  However, in some parts of the country, beech has been planted systematically, for example, John Holliday of Staffordshire planted some 94000 beech in 1791.  Beech is found throughout Central and Western Europe. It is generally found on freely draining (drier) soils (chalks, limestones and light loams) such as found in the Cotswolds, Chilterns and the Downs. Read more...

Today there are more deer in the UK than at any time since the last Ice Age.  They no longer have any natural predators in woodlands or fields. Total deer numbers are conservatively estimated at about 1.5 million and the rapidly expanding deer population threatens woodland biodiversity.  Over-grazing and browsing, particularly in ancient woodland, continues to have two very unfortunate consequences for conservation.  First, it can lead to a decline and loss in plant species in a given area, which often includes oxlip and bluebells.  Deer frequently damage saplings and cause other damage by stripping bark with their antlers. Read more...

There are some rare but beautiful woodlands around the coast of Britain nick-named the "temperate rainforest".  Yesterday, I visited one of these woodlands in North Wales and was mesmerised by it - ancient oaks and birch which had little timber value but immense ecological value - trees covered in different mosses, a carpet of soft and varied bilberries and ferns.  The wood had a damp and humid feel that encouraged liverworts, lichen and fungus and there was no obvious trace of human intervention - it felt just right for dinosaurs! Apparently these woods have evolved as a result of the Gulf Stream that keeps the area warm but also wet: this creates woodlands quite unlike any others in Britain.  From the top of this woodland you can see the sea.  Temperate rainforest woods like this must once have covered the Atlantic fringe of Western Europe from North West Scotland all the way round to the South of Portugal - they are rich in biodiversity and some species here are not found anywhere else in the world.  Bats love these woods, especially the greater and lesser horseshoe bats which enjoy the rich food source of invertebrates that thrive here. So the challenge for the owner is how to protect and manage these rare woodlands but it's not just a case of leaving them alone.  In the case of this particular woodland the plan is to graze it in the winter to protect the mosses, bryophytes and lichens and to ensure that natural regeneration takes place.  If the woodland isn't grazed the bramble and holly will create impenetrable conditions which will shade out the bryophytes and lichens as well as discourage birch and oak seedlings from emerging.  Even so, the intensity of grazing is important and Natural Resources Wales (NRW) suggests one sheep per hectare for the winter months.  Alternatively ponies can be used for such grazing but they need more management and attention than sheep. The damp and humid conditions are helped by the streams and waterfalls of these woods and the abundance of small plants means that there is constant evaporation.  In fact it is probably the difficult access and rugged terrain which has preserved these woodlands for so long - historically they were not suitable for agriculture or industrial forestry and so never got converted from their ancient state which goes back to the last ice age.  The sessile oaks are very important for wildlife but not very productive of good timber so they have often been left to grow quite mature.  Similarly the Birch trees have relatively low timber value which has been their salvation.   [caption id="attachment_20968" align="aligncenter" width="600"] Asymmetric distribution of moss on birch[/caption]