When one stands on any high point in Dorset and view the beautiful countryside laid out before you it is easy to think that it has always been the way it is now, a green and pleasant land. It is also hard to believe that plants and animals are in crisis. The truth is that the landscape you see has been continually altered and managed by human activity for thousands of years. Here are just a few key events that have shaped the countryside of today.Ice Age:The last ice age, now thousands of years ago, destroyed whatever habitat was here in Dorset before it started, although the ice itself did not reach quite this far. As the ice retreated the natural process of regeneration meant that pretty much the whole of Britain became covered in woodland, the 'wild wood'.Neolithic Man:Towards the end of the Neolithic period, around 3000BC, humans were developing a new way of living; no longer hunter/gatherers they were beginning to farm crops and animals. They were developing more efficient tools and they started clearing the 'wild wood' for fuel, building materials and to make way for new farming methods and stock keeping. Dorset has several Iron Age forts that date back to this time that enable us to imagine how they were living all those years agoThe Invaders:The coming of the Romans and then the Norman Conquest changed the way the land was managed and they brought with them crops and animals for food. We may think of deer, rabbits, pheasants and so on as part of our native fauna but they are not.In 1492 Columbus Sailed the Ocean Blue:This famous journey set in motion a series of voyages of discovery and started the collection of plants and animals from all over the new world. Called the archaeophyte age, plants and animals present before this date are generally considered to indigenous.Enclosure Acts 1605-1914:Over 5,200 parliamentary Acts of Enclosure between 1605 and 1914 transformed ownership of land and created the structure we know today. Self-sufficient peasants were forced to leave what was common land and go to work in the new factories of the industrial revolution. Farming and land management changed with fields created and hedgerows established to form boundaries.Agricultural Revolution:In 1701 Jethro Tull invented the steam powered seed drill that started a revolution in farming and other mechanised farm machinery soon followed. Not as effective as modern machinery of course but it did have a considerable impact on the way the land was farmed. Also around this time the British Empire started to form, it increased world travel and fuelled a passion for creating exotic gardens and more plants and animals where brought here from faraway places. Grey squirrels, sika deer and Canada geese, just some of today's problem species, were brought here in Victorian times to adorn gardens.Dig for Victory:The Second World War brought severe food shortages as U-boats attacked convoys in the Atlantic. This forced many areas not previously farmed to be ploughed and cultivated. Countless acres of precious countryside were lost forever in the fight for survival. After the war there was, naturally, a feeling that we did not want to get into the same position again and an emphasis on increased farming efficiency emerged along with new mechanised equipment and 'pest' controls.You Never had it so Good:In the late 1950's and early 1960's increasing economic growth meant a greater demand for raw materials, housing, roads and employment and many more acres of countryside were lost to the development of towns and cities and to mineral extraction and mining. This time was reflected in Harold MacMillan's famous election slogan "You have never had it so good!"Nature Reserves:If you thought that we have always had nature reserves think again! The response to the dramatic loss of natural habitat in the twenty years from 1939 onwards led to a move to start protecting what was left of the best wildlife sites and the 'nature reserve' came in to being and along with it organisations like the wildlife trusts dedicated to the protection of our natural environment. The course of human history over the last 5,000 years or so has brought us to where we are today with our natural environment and the pace of change is probably increasing and new pressures on the countryside are emerging, not least the effects of climate change.