An ancient horticultural practice is resurging, combining art and science, humanity and nature; this old practice has a modern name: arborsculpture. As far back as the 16th century, tree shaping was hinted at in paintings and literature. But it was not until the mid-20th century and the work of Axel Erlandson, the father ofmodern arborsculpture, that the art form truly flourished. As a young man, Erlandson was inspired by the sight of two conjoined branches in a hedgerow. He began experimenting and designing, and sculpted more than 70 trees into stunning horticultural and architectural specimens. In 1947, Erlandson opened a roadside exhibition in Scotts Valley, California, debuting his curiosities in the aptly named Tree Circus.
What Erlandson observed and used to great effect was a natural form of grafting known as inosculation. Rather common, the phenomenon occurs when trunks, roots, or branches in close proximity gradually fuse together; inosculation can arise within a single tree, or between neighboring trees of the same or different species. Over time, as touching limbs grow and rub against each other, the outer bark is worn off and the cambium layers of the branches heal together. The vasculature of both trees intermingle and are covered in new bark.
Besides grafting, arborsculpture also employs pruning, bending, weaving, and bracing to create the dramatic loops, twists, and knots of this art form. Many of the techniques are borrowed from related horticultural practices such as bonsai, espalier, and topiary. Not all species are suitable for such creative treatment. The trees to be shaped must be flexible and vigorous with thin bark that can be easily grafted such as willow (Salix), sycamore (Platanus), poplar (Populus), birch (Betulus), and Persian ironwood (Parrotia).
The potential of shaping trees for green construction is promising. However, arborsculpture is still based on the trial-and-error projects of a few pioneers. The movement is so recent, in fact, that Richard Reames and Barbara Delbol coined the term arborsculpture in their book, How to Grow a Chair–the Art of Tree Trunk Topiary (Arborsmith Studios, 1995). True to its title, living furniture is a popular application; so too is the prospect of living houses and architecture. The ability of growing trees to incorporate foreign materials such as metal and glass suggests that arborsculpture is a viable green alternative for urban design.
One exceptional instance of urban tree shaping lies in Germany. There, architect Ferdinand Ludwig’s Baubotanik, or Living Plant Constructions, showcases the brilliance of botanical engineering at its best. Among his creations are a three-story willow tower, an osier willow footbridge, and a silver willow bird-watching station. Ludwig’s Plane-Tree-Cube in Nagold, Germany, is a building that incorporates live sycamores on a metal structure that is open to the public.
Unlike their dead lumber-based counterparts, living architecture continues to combat soil erosion while providing oxygen, sustenance, and shelter. As integral parts of the ecosystem, trees can convert carbon into biomass, mitigating the effects of climate change. Even when harvested—essentially killing them—living architecture persists as a source of aesthetic wonder.
When asked how he was able to shape trees, the late Axel Erlandson often replied, “I talk to them.” Indeed, when mankind and nature work together, the results can be impressive.
An earlier version of this article first appeared in Living Green Magazine in April 2012.