Santa Monica

Robert Lobe hammers thin sheets of aluminum around trees and boulders. Assembled in the studio, these fragmentary casts have a fragile air. Portions of the metal skin are torn and squashed--a quick motion of the hand could, one feels, reduce them to rubble. That vulnerability seems an apt metaphor for the status of the environment in this age of developer greed and chemical pollution.

But there is a good deal more sensual and metaphorical play in these pitted, ghostly forms. Copying the contours of nature is somewhat akin to making tombstone rubbings--extrapolating a mysterious essence from the surface texture of a thing. Stripping real forms of the accidents of color, these pieces also oddly embody noble permanence underlying the gnarled eccentricities of specific chunks of nature.

At the same time, many works incorporate subtle tonal distinctions between shiny aluminum passages that draw attention to sharp corners and dull, anodized areas that glide the eye over generalized masses. There is persistent emphasis on process, thanks to the frank visibility of seams and wrinkles and the holes where bolts once fastened metal to wood or stone.

Some of these sculptures stake out a large space, like “Harmony Ridge No. 23,” a floor piece in which two tree trunks, one with abruptly chopped-off branches, rise from a coffinlike mound. Other sculptures cling to the wall, evoking greater or lesser connection with an imaginable landscape. “King’s Bluff No. 22” embraces the shape of a bumpy tree trunk and then bulges out gently into a protrusion that seems to float effortlessly in the air. Such paradoxes are welcome aspects of this strong and subtle body of work. (BlumHelman, 916 Colorado Ave., to July 5.)