Creating wooded landscapes

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Tree Gardens: Architecture and the Forest

By Gina Crandell

A professor of landscape architecture in many of America’s finest institutions, Gina Crandell has created a fascinating book exploring the use of groups of trees in landscape design.  While many studies have examined how trees can be managed to improve water quality and retention, promote botanical diversity, provide lumber and shade, or support sports and recreation, this must be one of the first to examine how groups of trees – from discrete groves to grand forests – have been manipulated over the centuries for aesthetic purposes.  After briefly exploring the difference between art and nature, the tended and the unintended, Crandell goes on to analyse 15 exemplary arboreal landscapes, examining how such elements as scale, context, species and spacing have been employed to establish the unique mood of each site. 

The exemplars are presented chronologically, beginning with the defensive ‘wooded circle’ surrounding the mediaeval Italian city of Lucca.  This tree-planted earth-wall was created in the 16th century to provide a defensive barricade round the city, which sat in the midst of a large, open plain.  Eventually eleven separate allées were planted round the city, each of same species, to create a distinctive arboreal wall.  Charting its evolution from military barricade through grand carriage-drive to public pleasure ground, Crandell applauds the city’s careful preservation of the wall.  Rather than treat each tree separately, replacing the sick, old or dead as necessary, the authorities have treated each allée as a distinct entity, periodically renewing each, to continue the distinctive, layered character of the wall. 

At about the same time that Lucca was creating its arboreal wall, Cosimo de’ Medici (1389–1464) perfected the ordering of nature to transform wilderness into art in his Boboli Gardens in Florence.  The distinctive quincunx form, which he copied from classical sources, imposed a neat, geometric grid, transforming mundane, domestic orchards into controlled architectural spaces.  In 17th-century France, Andre Le Notre (1613–1700) transformed the rural hunting lodge of Versailles into one of the world’s grandest gardens, largely through the use of bosquets – walled thickets of trees cut with military precision, to create axes that extend his formal gardens into the surrounding forests.  Hundred-year planting cycles have maintained these grand forest gardens, which are as famous today as they were in Louis XIV’s own time. 

By the mid 20th century designers were looking to the distant past for inspiration.  Carl Sorensen’s Musical Garden was inspired by Viking landforms; expressing his faith in art as a social force, Sorensen embellished the grounds of a rural factory with a grand ensemble of geometric hornbeam enclosures, which, like the music which inspires their name, serve no practical purpose at all.

Much of recent landscape practice has been concerned with regeneration, transforming obsolete industrial sites into public amenities.  Crandell introduces this theme with the 1948 Gateway Memorial Park in St Louis Missouri, built on an old railway yard.  Here, Dan Kiley perfected his mastery of spatial proportion by creating a distinctly modern American forest garden, which pays homage to the city’s past as a fur-trading post, frontier town and gateway to the west.  Metaphor is also behind the birch groves that embellish London’s Tate Modern museum; as birch is a pioneer plant which colonizes post-industrial sites, its use here to balance the abstract geometry of the revamped power station symbolizes the process of renewal, in architecture and landscape alike.  Munich’s 1995 Riemer Park, created over a disused airport, also employs an austere palette, using tree masses and sculptural landforms to create a landscape of dark, wooded enclosures and contrasting open sunny meadows linked by runway-like pedestrian routes.   The site of Zurich’s 1996 Oerliker Park was so toxic that the soil could neither be rehabilitated nor moved, so a capping layer of asphalt was used.  On the top of this an unlikely urban forest was created through the careful selection of shallow-rooting species and a tight schedule of strategic thinning.

Throughout the book Crandell focuses on strategies for the installation, maintenance, regeneration and replacement of urban groves.  She notes that their continued health depends on the selection and care of the trees, both before and after planting, as well as the creation of scientifically calibrated growing environments.   The study ends with Reflecting Absence, Michael Arad’s memorial forest for New York’s 9/11 site.  Consisting of 400 Swamp White Oaks placed in 30 lines, Arad created a forest around the two massive waterfalls that fill the footprint of the former towers.  Here again, much ingenuity and engineering skill were required to support such a dense plantation.  Irregular spacing creates the randomness of untamed forest while ensuring that should a tree be lost it would not mar the design; careful planning ensures that the trees evoke the grid of Manhattan’s street plan and create a wall around the fountains. 

Planting trenches hold 40,000 tons of soil, while drainage and irrigation systems and underground maintenance corridors allow the forest to thrive.  Though uncommon in urban settings, Swamp White Oaks were chosen because their shallow root system allows them to grow well in wet, dry, or poorly drained areas; they also tolerate soil compaction, they are strong and disease resistant, they retain their leaves into winter, and their coarse-textured bark forms a dramatic contrast with the refined granite planks of the pedestrian paths. 

With such careful analysis of the planning, planting and management of urban groves, this book would be of interest to city planners and cultural historians as well as the landscape designers at whom it is primarily aimed.

Tree Gardens: Architecture and the Forest  by Gina Crandell  is published by Princeton University Press. 120 colour and 20 mono illus, £25.00. ISBN: 978-1-6168-9121-3