Last Night's TV: Lost Land Of The Jaguar, BBC1<br />The Burning Season, BBC4

Lost Land of the Jaguar is a funny old beast. Not so much a nature documentary as a documentary about a nature documentary. Its setting, Guyana in South America, is home to one of the largest patches of pristine rainforest in the world, but nefarious logging companies are just aching to chop the place to bits. So a team of scientists, conservationists and film-makers went to the uncharted region to survey its flora and fauna, and use their findings to persuade the Guyanese government – and the international community – of the importance of protecting it. A second, unseen camera crew filmed the first lot for posterity, and this programme was the result.

This is all very admirable, but it doesn't always make for compelling television. Last week's opening episode began promisingly, with a luscious overhead shot of the spectacular Kaieteur Falls that was worthy of Planet Earth. But soon we were bogged down in an unsatisfying compromise between top-class nature porn and behind-the scenes exposition.

When you're watching a family of elusive howler monkeys hopping through the forest canopy, wouldn't you rather listen to a blast of Sigur Rós than some wildlife cameraperson whispering unscripted platitudes? "Ooooh... Oh, yeah... That's lovely... That's amaaazing!" Well, it might be amaaazing to someone who's been 30 metres up a tree for two days waiting for a glimpse of another primate, but those of us on the sofa are seasoned wildlife watchers now. We want spectacle: some death-defying tree-to-tree leaps, a monkey fistfight, or at least a bit of shagging. Instead, we got a few seconds of solemn leaf-munchery.

More exhilarating were the travails of the team. Steve Backshall, a telly naturalist and climber with the enthusiasm and high-pitched timbre of a schoolboy, began the episode caught in the open during a raging electric storm. By the end of it he was trying to catch 40 winks in a tent pitched halfway up a perilous 300-metre rock face. He and some pro-climber colleagues were scaling the remote Mt Upuigma to reach its untouched, Lost World-style plateau, but large chunks of the cliff had a habit of coming away in their hands.

The irony of Backshall's antics is that, since his safe return from Guyana, he broke his back in a fall at home in Gloucestershire, an injury from which he's still recovering. But this is where the show really got interesting. Forget about animals and rainforests in peril. What about the humans?

A late-night safety briefing gave them their first inkling that, much as the forest is fantastic and nature is great and all that jazz, it really would like nothing better than to kill and eat them. There were scorpions scurrying around the camp, a tarantula the size of a terrier nesting nearby, five species of deadly snakes and, if the scientists fancied a dip in the river, they had to negotiate the whopping great cayman that lay basking in the shallows. Possums purloined the humans' breakfast, a venomous centipede loitered in the ladies' dorm. But the team were undeterred. Beardy bugs expert Dr George McGavin is the sort of chap who ventures out after dark in search of the world's largest spider and its inch-long fangs. Last week, he was bitten by a zealous army ant. Last night, he was stung by a scorpion. What will it be next time? Swallowed whole by an anaconda?

Backshall, meanwhile, leapt into the piranha-filled river to net some tiny vampire catfish. They're the ones that swim up your pee and lodge themselves inside your penis with spikes. And there I was hoping they were just an urban myth.

Back in the forest, a platoon of army ants were about to feast on some just-hatched wren chicks, before mum turned up to shoo the insects away. The natural world may be amaaazing, but it sure is nasty. If there's one thing this programme managed to demonstrate, it's that humans should steer well clear of the rainforests, with or without chainsaws.

The Guyanese president is hoping to keep his forests upright in return for carbon credits, which were also the subject of BBC4's latest Storyville documentary, The Burning Season. Dorjee Sun, a young Australian entrepreneur with the same boyish energy as Backshall, was trying to find a business model for the protection of Indonesian rainforests from loggers and palm-oil plantations. The economics were complex, and confused not only me but the conscientious governors of three Indonesian provinces, bigwigs at Starbucks and eBay, and, at times, Sun himself.

Essentially, he wanted the Indonesians to sell the carbon-busting power of their forests to the emissions villains of the developed world in a carbon-offsetting programme. Carbon-offsetting and its dubious benefits are a controversial topic in the green community, but saving the rainforests is not. You only had to watch the lonesome orangutan picking through the remains of his fire-ravaged home at the start of the film to feel their loss viscerally. As his plan started to come together in the final reel, an exhausted Sun told us, "I feel like I'm coming down with something, and it could be hope." Now that's one rainforest bug I wouldn't mind catching.