The Heckscher Museum of Art invites you to observe Earth Day on Saturday by perusing a pair of environmentally themed exhibits inspired, directly or indirectly, by Henry David Thoreau, who was born 200 years ago on July 17.

“Thaddeus Holownia: Walden Revisited” and “Earth Muse: Art and the Environment” will remain on view at the Heckscher through the Thoreau bicentennial, each closing on July 30.

WALDEN TREES

Holownia, a Canadian photographer, created his “24 Tree Studies for Henry David Thoreau” over a period of two years, two months and two days — the same span of time during which Thoreau conducted his experiment on “simple living” on woodland his friend and mentor, Ralph Waldo Emerson, owned near Concord, Massachusetts. “Walden; or, Life in the Woods,” Thoreau’s book published in 1854, reflects the author’s belief that solitude, contemplation and oneness with nature bring humanity closer to the divine. It became a classic in American literature, and Walden Pond is now a National Historic Landmark.

At first, Holownia intended to document Walden Pond as it appears today, starting with panoramic landscape photographs, two of which are in the Heckscher show, along with a photo of Thoreau’s gravestone. But later he came up with more intimate means of conveying the affinity with nature that Thoreau sought. The 24 black-and-white tree images making up the vast majority of “Walden Revisited” resemble portraiture. Some trees appear almost anthropomorphic. One seems to be looking back at you with a single large eye. Scars from lightning strikes, ravages of time and various other deformities tell a story of the tree’s life.

Heckscher curator Lisa Chalif arranged the photos to create “an immersive experience, as if you’re standing in the middle of a forest.”

EARTH AND SKY

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To get to “Walden Revisited,” you encounter the related “Earth Muse” exhibit of works by seven artists — six of them Long Islanders, full or part time.

Photographer Barbara Roux creates literally reflective images with a mirror in “The Earth Views the Sky” and “Ecology: Glass.” Alex Ferrone’s coastline aerial photos, with no readily identiable reference points, are disorienting bird’s-eye abstracts. Winn Rea’s 3D topographical “maps” of the Adirondacks, with shadows cast over wide swathes, deliver a similarly puzzling effect. Melissa Fleming’s photograms, created by immersing light-sensitive paper in ocean waves, captures sand and other sediment in random, swirling patterns.

In Peter Beard’s “Machine in the Garden” collage, man’s imprint on the African wild appears shockingly direct and violent. Michelle Stuart applies earth directly to her art with dirt from sites — one is in the Yucatán — surrounded by snapshots of nearby landmarks. More ecologically disturbing is Stuart’s botanical series of extinct plant life. It’s displayed next to New Orleans artist Brandon Ballengee’s Audubon colored prints of animals in which the now-extinct creature among them has been cut out. Ashes from cremated cutouts of the gone-forever beasts are placed in rest-in-peace etched-glass urns.