Sir David Attenborough has voiced concerns over conservation and climate change with Donald Trump taking office.
The veteran broadcaster, who spent time with former president Barack Obama for a special BBC programme on the environment in 2015, hopes "more than I can say" that Mr Trump does not take the US out of the Paris Agreement.
The new president has previously described climate change as a hoax invented by the Chinese to undermine US manufacturing and pledged to withdraw from the Paris Agreement, the world's first comprehensive treaty to tackle greenhouse gases.
He has also pledged to back coal power and abandon President Obama's efforts to tackle US climate emissions through the clean power plan.
Sir David, 90, has previously warned Britain will struggle to get its voice heard in conservation debates if the country completely breaks away from the EU in the wake of the Brexit vote.
Speaking in Edinburgh, where he collected a £250,000 donation from the People's Postcode Lottery for conservation charity Fauna and Flora International, he said: "We will have to see what happens in the United States.
"One of the great causes for congratulations and optimism was in Paris where there were agreements signed about what to do about climate change and America was very, very important in that.
"As was China, as was this country and many others, and for those of us who have been working for world conservation it was a very important occasion.
"We'll have to see what President Trump thinks he's going to do about that. I personally hope, more than I can say, that America will not withdraw from those commitments."
Sir David said he was delighted at the reception for his recent series Plant Earth II but hit back at criticism from Springwatch presenter Martin Hughes-Games, who said the show "breeds complacency" around conservation by focusing on the beauty of nature.
He said: "It's very difficult to get people to protect things and work for things that they've never seen, or don't understand.
"People won't protect things if they don't know about them and it's very important that they should not only know about them, but understand the way they work.
"Human beings are dependent on the natural world for every mouthful of food and every breath they take, and they ought to be aware how dependent they are but also how precious the natural world is.
"The BBC does lots of different programmes and they certainly do programmes in which you see how splendid things are and how fascinating things are, and how valuable they are, but also that they're in danger."
The success of Planet Earth II, which attracted around 12 million viewers weekly, is to be followed up with a return of Blue Planet.
Sir David said: "Another success a few years back was Blue Planet about life in the sea, or life in the water.
"We are preparing, in the same way we had Planet Earth II, to get Blue Planet II too. It's on the stocks right now."