Saturday, 14 July 2012

Personal Experience of Volcanoes and Wildlife 1

Over the last day or two, I have been thoroughly enjoying the BBC 2 series Volcano Watch. There have been some fantastic images, as well as links between volcanic activity and the wildlife associated with them. Over the last twenty years or so, I have had the great good fortune to be a leader of wildlife holidays and to lecture on cruise ships. This has taken me to many parts of the world and several have been in areas with considerable volcanic activity.

My first experience of a volcanically active part of the world was in Costa Rica  in 1990. Our local guide told us that in 1964 when President Kennedy visited Costa Rica, the country gave him a twenty one gun salute. This was the violent eruption of Volcan Irazu, a mountain over ten thousand feet, which can be seen from the capital San José. The eruption was considerable, and the city was affected by a layer of ash.

When I first visited Volcan Irazu in 1990, there was a whiff of bad eggs in the air, the crater which I was told at the time was the largest on earth was empty, and the cone sides contained masses of eroding ash.

The main, most recent crater of Volcan Irazu photographed
in 1990
The most recent crater photographed in 1994 and now
filled with a sulphurous lake
Cloud forest on the slopes of Volcan Irazu affected by
pyroclastic flow

By 1994 and my second visit, it had filled with water, and had a sulphurous lake in the cone, and the water appeared to be boiling. One of the highlights of the day for my group was to have a look at cloud forest on the upper slopes of Volcan Irazu.

Finding an open piece of woodland that would give a good opportunity to scan, I stopped the coach. The trees were stunted with considerable expanses of open grass between them. The terrain had a certain similarity with the New Forest, and I wondered what animals could be responsible for the grazing. Certainly, there was no evidence of large numbers of cattle or horses up in the mountains. One stunted tree supported a mass of flowers in its upper branches, which were only about ten feet above the ground. I noticed these flowers had attracted a tiny, jewel like hummingbird. This was the Volcano Hummingbird in its Mount Irazu form, a species confined to a very few of the higher volcanic mountains of Costa Rica. It turned out that this very unusual woodland had been created by a pyroclastic flow that had passed over the cloud forest, stunting it, killing most trees and creating a unique landscape and ecology.
Volcan Irazu photographed in
1994 in a more pensive mood

Volcan Poaz photographed with a plume of steam, and still
quite active

Saturday, 7 July 2012

Dynamic Woodland

The secret to understanding the ancient woodland cover in northern Europe and America is to appreciate the relationship between meat on the hoof, and deciduous woodland. Shortly after the last ice age, enormous herds of steak rampaged their way across the countryside, ripping, munching and felling the vegetation in the countryside.

Vinney Ridge. A large beech tree in New Forest woodland
    dominated by beech
Although European rainfall is higher, as they do in modern Africa, the northern equivalent of elephants, woolly mammoths, would have torn down trees, and brought down branches for food. All this dynamic activity would have had a profound effect on the ecology of those days. Native Americans saw the importance of this balance, and did not treat the huge herds of bison that roamed as an unlimited resource that would continue without some sort of management. Not so the stone age human equivalent in Europe. Here, bison and grazing animals were brought to the verge of extinction in prehistoric times through uncontrolled hunting and lack of management.

It was Franz Vera who, in his ground breaking book Grazing Ecology and Forest History, brought to the attention of ecologists the importance of the balance between grazing and woodland in the northern hemisphere. An understanding and appreciation of the finest, most natural non man managed woodland moved from forests in Poland to the British New Forest. The New Forest consists of a mosaic of habitats which have been created by herds of grazing animals. These animals create areas of grassland known locally as lawns. The ancient New Forest woodland contains little regeneration, a more open shrub layer and a particularly impoverished ground flora. The tradition in medieval Britain for deer hunting by the king and his nobles created the New Forest, and the English medieval deer parks. Since William the Conqueror, the New Forest has been managed, one way and another primarily as a food resource for grazing animals.