Grassfed animals and tree density

https://vimeo.com/138177205

Most of Europe was forest before the rise of civilizations

http://www.nature.com/nature/journal/vaop/ncurrent/pdf/nature14967.pdf

https://www.facebook.com/nature/videos/10153246179773167/

http://www.washingtonpost.com/news/energy-environment/wp/2015/09/02/scientists-discover-that-the-world-contains-dramatically-more-trees-than-previously-thought/