Exhibitions, whatever their subject, should tell a story; occasionally, they can tell the story by way of a general survey of their subject - an artist's recent work, or their life, a movement, a cultural idea. The current exhibition at the Barbican, Radical Nature, succeeds in doing neither of these things, while coyly suggesting all the while that it is trying to do both.

One has the impression that somebody in marketing fixed upon art and the environment as a subject guaranteed to appeal to some target audience; the hapless curatorial team sets out with a rickety supermarket trolley (and the budget for a family camping trip), taking down from the shelves any product of artistic or architectural practice that has the word "eco" on the packaging. When this exercise begins to seem as silly as it sounds, somebody suggests that it might be dignified by the addition of random works by a few equally random great names from the sixties and seventies.

As a serving suggestion: up-end the cart in the Barbican's intransigent exhibition space, stir the stuff around a bit, half bake, and then dress with a fat catalogue.

To begin with the catalogue itself: an essay by the curator, Francesco Manacorda, that breathlessly (and half-heartedly) attempts to string the disparate pearls together; a think-piece by TJ Demos that preserves some dignity by omitting to mention the works of most of the practitioners represented; and an introduction by Jonathon Porritt, worthy but clearly demonstrating he hasn't a clue what this is really all about, finds it marginal, and doesn't much care.

Again and again, the exhibition falls victim to its own ambition. Take for instance the unavoidable (if unintended) juxtaposition of the relics of the Joseph Beuys's Honey Pump at the Workplace with the Philippe Rahm installation - commissioned for this exhibition - of a series of wind instruments connected by paper tubing to a inflatable diaphragm. The latter is the record of a noisy, uninteresting, performance event that might never actually have taken place - it did not help that the accompanying projector was broken; in contrast, the industrial fragments of the Honey Pump are at least as powerful as the wonderful machine itself, in use at Documenta in 1977, and now even more plangent for being inert. The key problem is probably just this: a younger generation preoccupied with making hermetic objects for exhibition that frustrate the central enquiry of the landscape debate for designers and artists, into time and memory, and above all into scale.

Such comparisons are irresistible, and often only too literal. What does Simon Starling's floating Island for Weeds do that Robert Smithson's Floating Island to travel around Manhattan did not manage with more grandeur, and with superb timeliness, in 1970 when it was conceived?

"The public would have more pleasure and more to learn with less effort from going for a walk in Hyde Park"

Or Lara Almarcegui's left-over urban spaces beside Gordon Matta Clark's; or Anya Gallaccio's gallery trees beside Smithson's (again). The saddest little moments in the show are the "recreations" of works from the sixties by Hans Haacke and the Harrisons. The objects are not any longer in themselves the real thing; their moment (and it was a very good moment) has passed. Besides, isn't there something new out there? This is a question one should ask as much about the later work of both artists, as about that of others.

In a sense, these curatorial failings are emblematic; they certainly provide one possible account of why the ecological movement in architecture just now so reliably produces so little that is either good architecture or coherent ecology.

The debate is too diffuse, too "correct", too divorced by current politics from an understanding that art and nature have been yoked in a pas de deux at least since Pliny. Even, perhaps, a bit feeble intellectually - we should all by now know Raymond Williams's declaration that "nature" is a word with one of the most complex sets of meanings in the English language.

And practice, by artists and architects both, is too afraid of itself, too critically self-conscious, to make the big gestures required. One can address the environment without having to be environmentally correct. Consider for a moment the carbon footprint of Michael Heizer or of James Turrell, neither represented in this show, both of them literally moving mountains in the American west for tiny audiences that can come only by invitation.

I have a feeling that the Barbican public would have more pleasure, and more to learn with less effort, from going one fine morning for a walk in Hyde Park. The line that connects Bridgeman and Brown to the land artists of the sixties is clearer, and the work on view is more convincing than anything contemporary on the same theme that one can, or should, put in a gallery.

URL:

http://www.bdonline.co.uk/story.asp?sectioncode=429&storycode=3145179&channel=783&c=2