The author's collectivist approach involves fallacy for a number of reasons.

For example:
“The total cash cost to buy all the world’s remaining areas of high biological diversity at current local land-sale prices is estimated at $20 billion per year for ten years. This is less than annual US expenditure on soft drinks. So yes, the world can afford it.”

It’s like saying the value of the housing stock in Australia is $x billion, a figure derived by adding up the notional cost of each house. Since as a matter of fact no-one is ever in the position of buying all the housing at the same time, consequently the price data are a fiction. They have no application, and no meaning, either in theory or in practice.

It is not valid to regard all the world's property as held in common, and “the world” as a decision-making entity, with the author exercising a God-like supervision, and a power to decide for everyone in the world including all those who disagree with him.

If it were true that the author represented everyone in the world, the solution would be simple: just buy the remaining areas of high biological diversity. The fact that people aren’t doing that is because they are motivated by different values from the author, a well-fed westerner using a long time-frame, and purporting to decide the fate of the whole world. The author doesn’t agree with their values, but then, he doesn’t know what they are either, does he?

He is right that private businesses should not be publicly subsidised. But how anyone can think that natural resources will be better conserved by expanding the tragedy of the commons is a mystery.

You are exaggerating the importance of wilderness. While wilderness does provide the benefits that you claim- such as acts as a filter of air and water, provides a resource of exotic chemicals useful for medicine and also provide tourism dollars- the extent is not as important as you claim.
Firstly, wilderness does clean the air of man made particulate pollution- however, the VAST majority of particulates are removed by gravity (for large particles) and precipitation. Also, it is ANY tree that removes pollution- not just wilderness, ie: planted forests and farmed crops and planted ornamental/recreation space trees will also remove pollution. Indeed, since high levels of pollution occur in cities, planting more trees in and around a city has a much greater effect on air quality than preserving a native wilderness area hundred's of miles away.
Secondly, I agree that many medicines are derived from compounds found in other species. However, since we have areadly found cures for the diseases that used to cause the greatest problems (such as polio, small pox,..,etc) we are now left with diseases that effect much smaller sets of the population (except possibly for AID/HIV). So we are getting diminishing returns on medical research. Hence it becomes a question of greatest good, ie: will destroying a wilderness to produce food and materials keep more people alive/healty than would die/be sick from an illness with a cure potentially availalbe due to some species unique to that wilderness. I think any rational person will see that the answer is yes because this is what the evidence tells us-- there are now more people alive today than at any other time in history-- because we have destroyed the wilderness are replaced it with farms and industry. Also these days computer modelling for drugs is used more and more in medical research reducing the need for perserving exotic naturally occurring compounds. ... continued below...

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Thirdly, the tourism point is just an economic question of which is more profitable: the tourist dollar or the money made from "destroying" the wilderness. This question is best answered by the economic practice of the population- since if people want a wilderness then they will pay tourist dollars to keep it is kept as a wilderness. It is not answered by an individual or a small group who thinks that they are high and mighty and know what is best for the rest of the population.

Oh no Ralf, people with policy analysis skills are on to you. Hide!

I know where you're coming from but honestly, we're not consuming several times more (insert subject) of what the earth can produce. One reason is that logically it can't be done. We only consume what the earth produces, no more, no less. I think you're trying to say we're eating the future.

Someone recently hit the nail on the head and talked about the amount of pollution that developed nations are producing. Here you're on strong ground. The problem never has been the NUMBER of people, it's the waste that high consuming developed nations produce and their inadequate waste disposal policies.

Why is it that these blokes always talk about trees, when ever they talk wilderness. By far the greatest wilderness is the ocean. Always was, even when the dinosaurs ruled, & always will be. This wilderness does five times more than all the trees, in cleaning up polution, & oxygenating the air.

Then we get this love of wild jungle, as if it was something warm & cuddly.

What rubbish. Unless Ralf is 100 times more practical than he sounds, I could kill him real quick, just by dumping him a kilometre from the coast of a few of the Whitsunday tropical paradise islands. He'd never be seen again. Cuddly is one thing wildenress aint.

It can be funny though. I was part of many search & rescue missions for people who did not think wilderness would bite.

On one occasion a couple of German back packers, wandered off from Palm Bay, at lowish tide one afternoon, down the foreshore of Long Island. They spoke to no one, as they were only going beach combing.

Two hours later, & only 1500 yards from the resort, they found the beach they had combed, was now under a a lot of warer, with the incoming tide. They tried returning just above the tide line, & although they wore sneakers, & had large towels to wrap around themselves, in just shorts, & a top for her, they were soon ripped to bits, & gave up.

When the tide was low, in the early morning, they found it too dangerous on the foreshore, in moon light.

They had been missed, & at first light next morning, 4 boats, & a couple of aircraft set off looking for them. An Air Whitsunday plane called that he'd found them, even mentioning the girl was wearing a black bikini. I was nearest, in a 23 Ft shark cat, & went around.

I found a snall herd of goats, one of them black & white. That pilot was known as Goaty for months. A little later a large ferry spotted them.
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I was in the only small boat that could get in close, so I picked them up. It was hard to see any spot of skin, on either of them, that was not scratched, or bitten. Typically tough german tourists, there was not a word of complaint, just gratitude at being rescued, & perhaps some excitement at their adventure.

I have been involved in a number of these rescues from the mild "wilderness" in that area. In many other real jungle places, it's not worth looking.

So If you want a real wildernes experience, rather than a nice safe national park walking track, stick to the wet one, at sea, those trees can get nasty.

Oh, & if you are ever on one of those national park walking tracks, don't ever try to take a short cut through the bush, even if you can see your destination a few hundred metres away, more than a few have died doing that.