Soil type (grain size, pH, humus) is a vital part of any habitat formation but other factors play a part as well. Relief and Aspect:Relief is a term used to describe the height and shape of land; a relief map shows the height of land by use of contour lines and colour shading. In general, higher ground is cooler than lower ground and some plants prefer cool conditions, others need warmth. Aspect describes the direction in which a slope faces. A north facing slope will have less light and be cooler than a slope with a southerly aspect. The Purbeck Ridge in Dorset has very different vegetation on its north side than its south side. The degree of slope can also be significant with steep valley sides forming differing habitat to that of flat areas towards the mouth of rivers. Steep slopes can also minimise human impact on habitats. Dorset is very much part of lowland Britain (but it does have some high hills!)Longitude and Latitude: The position of a site on the globe also has a profound effect on habitat. Southern Britain is somewhat warmer on average than northern Britain and temperature is important to plants and insects in particular. The west of Britain has a higher rainfall than the east and that affects plant growth too. The north and west tend to have higher ground, in places mountainous, formed from volcanic (igneous) rock whereas in the south and east the rocks are sedimentary. Sites close to the sea will be influenced by salt in water and in the wind; exposure to stronger winds will have an influence too causing soil erosion and structural damage to plants themselves. Dorset is in the south west and has a warm, moist climate influenced by the sea. The bedrock is totally sedimentary; chalk, limestone, sandstone and clay.Human Intervention:By far the biggest factor influencing habitat is human activity both now and historically. There are many ways in which we influence our environment and natural habitats including arable agriculture and livestock grazing, woodland plantations and timber felling, mineral extraction and mining, housing and industry, recreation, travel, the list goes on. It is not possible to over state the effect of human intervention on our natural habitats both directly by our daily activity and indirectly through side effects such as climate change. Human intervention has shaped the countryside as we see it today, not just what we do today but what we have done over thousands of years.