If size were all it took to make art count as bold, then the sculptures of Emilie Brzezinski would rattle any viewer. She takes the huge trunks of fallen or soon-to-be-felled trees and roughly carves and hollows them into massive, almost abstract forms. Her works can rise up high like living trees or they can hug the floor like storm-shattered hulks. Either way, it's not clear there's all that much value added to the wood by what Brzezinski does to it. Old tree trunks are glorious things, as any child who's hidden inside one knows, and Brzezinski's chain saw doesn't much alter the glory we've all already felt. Of course, the Katzen's super-aggressive spaces don't help these works impose themselves on us: Compared with what an architect can do in concrete and steel, nature's biggest creations can seem mild-mannered. To really compete with a space as powerful and raw as the Katzen's 6,000-square-foot concrete-walled sculpture garden, where some of Brzezinski's "trees" have been planted, you'd need the most aggressive products of today's art scene: raucous performances or huge experimental structures or rap-inspired turntablism. Leading institutions such as the P.S.1 Contemporary Art Center in New York have similarly crude open-air spaces, and they manage to find art alive enough to energize them.

At the Katzen, Brzezinski's sculptures risk looking like the absent-minded whittlings of some cheery forest giant.

Not out of the woods yet: A true trunk show.