Dr Iain Stewart uncovers how, over thousands of years, the actions of mankind and the climate nearly led to the downfall of Scotland's trees and forests. It was only in the 18th century that man realised the extent of the damage to timber stocks, and measures were taken to re-populate the landscape. The impact was profound, but not everyone agreed with the results.

For centuries, the beauty and drama of Scotland's landscape has been regarded by most visitors as natural. But in 1950, an eminent ecologist concluded the Highlands had been devastated. Once it was rich and diverse he said, but humans had destroyed it and in the process created what he described as a wet desert. Dr Iain Stewart discovers how man made the proverbially beautiful Highlands.

This week Dr Iain Stewart reveals how our hearts, and not our heads, have ruled the least understood landscape of them all - the sea. The public's emotions have played a defining role in the fate of Scotland's maritime creatures and the upshot has been a form of lottery. While some species, like seals and sea birds, have been protected, others - like cod - have been fished nearly out of existence.

As 'natural' icons, Scotland's rivers and lochs represent how the nation imagines itself. However as Dr Iain Stewart discovers, the only thing that happens naturally is rain. As soon as it hits the ground it's ours and we do with it what we will. Today there are scarcely any rivers or natural large bodies of water left untouched by human activity. This is the story of how Scotland's waters became some of the most managed on earth.

During the Industrial Revolution, Scottish scientists and engineers helped unwittingly set off a chain of events that today we know as climate change - a process that is transforming our atmosphere and warming our planet. Professor Iain Stewart looks at how Scotland is on the verge of another revolution: the transformation of a carbon economy to a green one.