How do you put a price on nature?

That's exactly what the British government has just decided to do: they've set up a Natural Capital Committee to assess the economic value of every tree and butterfly in the land.

This week, One Planet speaks to the chair of the Committee, economist Dieter Helm. We ask him what natural capital is, why he wants to put a value on it - and Mike puts some of London's trees at risk by asking the public how much they'd pay him not to cut them down.

Also on the show, an investigation from award-winning photographer Toby Smith - are journalists reporting on environmental issues increasingly vulnerable to attacks and intimidation?

And we hear from Liberia, where foreign investment is finally starting to flood in after years of civil war. Big international companies are arriving and taking over vast areas of the country - in a move some local farmers and activists describe as a land grab

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