Ipe is the most common tropical hardwood decking material in the United States, but the way it is harvested has raised concerns among ecologists. 

By Jane Hutton

“This John Chipman bench was planted 500 years before Columbus sailed for America,” reads a Landscape Forms ad from a 1973 issue of this magazine. The familiar slatted bench is shown towering over a forest canopy. Its base is anchored to a colossal redwood stump. “When you have a site furnishing job to do, think about Chipman in 1,000-year-old redwood,” the ad says. “Even if your benches only have to last another 100 years.”

Old-growth redwoods yield beautiful, warm-toned lumber with a straight grain. The wood is low in resins and rich in polyphenols, which makes it both fire resistant and impenetrable to fungi and insects. Because of these desirable traits and the wood’s wide availability in the midcentury, modernist landscape architects in California used it extensively. Thomas Church even acted as a spokesman for the California Redwood Association in a 1956 ad, calling redwood one of his “most versatile materials.”

By the 1980s, landscape architects’ enthusiasm for old-growth redwood had waned. Harvest rates plummeted because of the near decimation of populations, and many of the remaining stands were incorporated into parks and preserves. As the use of old-growth redwood declined, other materials appeared on the market: second-growth redwood, chemically treated softwoods, and tropical hardwoods. When the redwood decking of Church’s Fay Garden in San Francisco was restored in 2006, it was replaced with a tropical hardwood called ipe (see “Degrees of Preservation,” LAM, January 2009).

Most ipe (pronounced ee-pay) comes from rain forests in Brazil and Peru. Like redwood, ipe lumber resists decay and is dimensionally stable; unlike redwood, it is extremely hard and dense—nearly five times as heavy as old-growth redwood. Freedonia Group, a company that provides information for businesses, estimates the U.S. decking market will grow to $5.7 billion by 2016 and “among wood types, tropical hardwoods will see the fastest growth.” Ipe has become the wood of choice for many public landscape architecture projects. It can be found in the renovated Coney Island and Atlantic City boardwalks as well as in the first phase of New York City’s High Line.

As with old-growth redwood, ipe’s use is controversial. Four months after the High Line’s opening in 2009, people involved with the Rainforests of New York campaign hung a banner at the park’s West 17th Street amphitheater, which is made with ipe certified by the Forest Stewardship Council (FSC). “High Crime on the High Line: FSC Lies, Amazon Wood Is Not Sustainable,” it read. The campaign, initiated by members of Rainforest Relief and the New York Climate Action Group, criticizes the use of tropical hardwoods such as ipe in public landscapes. New York City is the largest consumer of tropical hardwood in North America, it says.

When Rainforest Relief began speaking out about this issue, it promoted the use of FSC-certified tropical lumber, explains Tim Keating, the group’s executive director. But since then, it has become skeptical that certification is a reliable indicator of sustainable production, citing the FSC’s willingness to certify old-growth forests in the Amazon.

The issues surrounding ipe are typical of a new set of material challenges that landscape architects face today. We are increasingly interested in where materials come from and what their production entails from an ecological and social perspective. But it is often hard to find good information on this subject. I’ve specified ipe myself, and in an effort to understand more about this popular wood, I followed some back to its Brazilian habitat.

Belém, the capital city of the Brazilian state of Pará, is strategically located where the Rio Pará—the southern arm of the Amazon River—pours into the Atlantic Ocean. The city has been the port of trade for goods harvested in the Amazon basin for several centuries. Established as a Portuguese colony in 1616, the city saw economic booms from cacao in the 17th century and rubber at the end of the 19th century. Today, it is home to a plethora of major environmental protection and research organizations such as the Amazon Institute of People and the Environment and the Amazon Environmental Research Institute as well as lumber exporters, including Timber Holdings USA—the lumber supplier for the High Line.

The Instituto Floresta Tropical (IFT), which is also in Belém, straddles these domains of environmental protection and forest extraction. The group conducts independent research and provides training and certification in sustainable forestry for logging companies, government agencies, and community landholders. I asked Marco Lentini, the technical manager of IFT, to show me some ipe growing in its natural habitat. Lentini invited me to the Roberto Bauch Forest Management Center, an eight-hour drive to the southeast of Belém. But he warned that we might not see many live trees: “Looking for ipe is like following a trail of stumps.”

Marlei Nogueira, who leads courses in sustainable forestry practices, drove us to the research center, where we began our search. He cleared a path through the vines and the dense undergrowth toward a single mature purple ipe. At a meter and a half in diameter and 40 meters high, the tree dwarfs those around it. The species, Tabebuia impetiginosa, is locally known as ipe roxo for the flush of purple flowers that appear after the dry season—a trait that makes it a popular urban street tree.

T. impetiginosa and T. serratifolia (known as yellow ipe) are two of the most exploited in the group of about 20 species collectively marketed as “ipe.” These two species range from the Brazilian Amazon to Mexico, yet they appear at low densities; a mature tree is found once every three to 10 hectares, according to the ecologist Mark Schulze and his colleagues. Their slight, winged seeds get caught in foliage as they fall from the canopy and are quickly consumed by tapir and deer on the forest floor. The seedlings, once established, require specific lighting conditions controlled by the size of forest gaps. Lentini explained that these traits, along with characteristic slow growth (less than 0.5 to 0.7 cm growth in diameter at breast height [DBH] per year), produce a population structure that comprises mainly old, large adults with few juveniles.

Nogueira made a small incision behind the tree’s bark and removed a slice of the sapwood for us to inspect. At his prompting, we tried to rip the shiny, yellow tissue with our fingers and found that it is impossible. Ipe species have thick-walled fiber cells that produce extremely dense and strong wood. The Janka hardness test, the industry standard for measuring the hardness of wood, determines the pressure required to embed a small steel ball into the surface of a wood board. At 3,680 pounds of pressure, ipe’s Janka score is three and a half times greater than teak, and nearly nine times that of second-growth redwood, according to the U.S. Department of Agriculture. Ipe wood is so hard that the U.S. Navy considered it for producing ball bearings during World War II; it is so heavy that it sinks in water. Furthermore, as the tree grows and sapwood is converted to heartwood, biochemicals known as extractives are deposited into heartwood cells and make the wood highly resistant to decay. These qualities make ipe a valuable commodity. According to Brian Lotz of Timber Holdings USA, a cubic meter of ipe lumber products is worth some $3,000. At that price, a single mature tree could be worth nearly $9,000.

We spotted a seedling at the base of the large tree. Nogueira picked off one of its five-leaflet leaves and showed us how it matches the logo on his IFT uniform—a stylized ipe leaf. He explained that ipe was chosen as the institute’s emblem because it represents a great conundrum for the region. The desire for highly valuable, yet sparsely distributed trees like ipe has exacerbated the processes that drive deforestation in the Amazon. The typical sequence of uncontrolled deforestation involves the cutting of valuable species, the clearing of remaining biomass for charcoal production, and finally the planting of crops for cattle grazing. As desired species are eradicated, the logging frontier and associated road construction advance further into unlogged interior forests.

The harvest of big-leaf mahogany (Swietenia macrophylla)—also prized as a decking material in the United States—is a textbook example of these dynamics. In 2003, big-leaf mahogany faced commercial extinction owing to illegal logging and a rampant export market—60 percent of it bound for the United States—and so it was listed in Appendix II of the UN-chartered Convention on International Trade in Endangered Species. This regulation still allows the wood to be traded but limits the quantity and sizes of trees that can be harvested. It has alleviated some of the pressure on mahogany populations, but similar exploitation patterns are being repeated with other species like ipe, whose export market increased by 500 percent between 1998 and 2004. Schulze and his colleagues assert, “Tabebuia appears as vulnerable to uncontrolled logging as mahogany.” Ipe, they conclude, is “the new mahogany.”

Back in Belém, the forest engineer Eduardo Eguchi explained how the Brazilian government regulates logging. Companies must produce a “sustainable forestry management plan” that includes an inventory of all commercial trees with a DBH larger than 40 centimeters and a description of species to be harvested. The Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) is responsible for reviewing management plans, granting licenses, and conducting inspections. Within a licensed site, logging companies that use heavy machinery are limited to taking 30 cubic meters of lumber per hectare for each 35-year cutting cycle. Along with the protection of any endangered species, 10 percent of any species in a lot must be retained as a seed source, no species with fewer than three individuals per 100 hectares may be harvested, and, unless otherwise legislated, no trees smaller than 50 centimeters DBH may be cut.

Since 1969 it has been illegal to export whole logs from Brazil. The sawmills of the Icoraci District, to the north of Belém, process logs that arrive by river and road from various regions of the Amazon. Marcia Teixeira of Timber Holdings USA took me to one of the mills that her company purchases from. On the day of our visit, the mill was cutting ipe almost exclusively. Mounds of behemoth logs, some one meter in diameter, surrounded the roofed, open-sided structure. Inside the mill building, activity circled around the main saw: A colossal hook anchored to the trusses was lowered to catch the edge of a three-quarter-meter-square section log. The cumbersome hook flipped the log so that it was properly aligned as three men slowly guided it toward the blade.

At the front of the building are floor-to-ceiling stacks of smooth, warm-hued ipe two-by-fours drying. Teixeira works with the mill’s grader to check quality and to verify the moisture levels of the lumber. Boards are air- or kiln-dried before shipping to ensure lighter and therefore cheaper freight. The ipe that Timber Holdings USA buys comes primarily from the states of Pará and Mato Grosso. Logs are typically transported from interior forests to rivers by truck, and then by barge to port cities like Belém. Timber Holdings USA purchases sawed wood and ships it directly from Brazilian mills to New York City’s port. And from there it is distributed to warehouses in New Jersey, Texas, California, and New Hampshire.

In a hotel lobby in Belém, Teixeira walked me through the string of documents required to secure a legal shipment of lumber from Brazil to the United States. Each shipment of sawed lumber is associated with a unique number and set of documents that describe its cadera de custodia or chain of custody. In 2006, IBAMA instituted the Document of Forest Origin system, whereby all forest products are tracked digitally in real time. According to the Brazilian government, this system, along with new surveillance methods, has significantly increased its ability to control illegal logging and stem deforestation rates. Teixeira’s job involves the meticulous administration of Timber Holdings USA’s lumber on its way out of Belém, maintaining records of the locations, handlers, and licenses associated with each link of the chain, from forest to importation. Tightened regulations, along with amendments to the U.S. Lacey Act, which prohibits the trade of any illegally harvested plants or animals, have required companies to be even more diligent. Timber Holdings USA has developed a continuing education course to help clients navigate the controls and develop specification language, Brian Lotz told me. The paperwork is so arduous, Teixeira said, that “illegal companies can’t survive.”

On the road to and from the IFT field station, we regularly saw officials from IBAMA and SEMA (Pará’s Environmental Secretariat) stopping trucks loaded with logs to check their documents. But this legal paperwork can provide an administrative mechanism for concealing illegal wood, Nogueira said.

In 2012, the British Broadcasting Corporation reported that some logging operations had bribed or bullied landowners to produce legal forest management plans, which were then used to cover illegal lumber from a different forest. The scam is known as “heating” the wood, and the vast terrain and complex network of actors related to logging in the Amazon make it challenging to control. Illegal logging in the Brazilian Amazon fell by 50 to 75 percent in the past decade, according to a 2010 report by Chatham House, a policy institute in London. But estimates by the group suggest that 35 to 72 percent of all logging in the Brazilian Amazon is still illegal. Chatham House came up with these figures by contrasting the amount of legal wood produced with the total amount of wood consumed domestically or exported.

Even if all illegal logging could be stopped, that might not stabilize ipe populations. To actually produce a sustained yield of a given species, the cutting intervals and quantities must be calibrated to match regeneration rates. The Tropical Forest Foundation, an international not-for-profit, asserts that conventional, legal logging in Brazil is “detrimental to the forests’ future.” The foundation and others promote “reduced-impact logging,” which involves longer cutting cycles, harvesting methods that protect neighboring trees and reduce soil erosion, and improved working conditions. These methods have been adopted by various certification programs that are trying to reduce the impacts of conventional forestry.

The FSC, established in 1993, has created the most recognizable third-party certification system for sourcing wood in the United States. It is the authority on certified wood for the Sustainable Sites Initiative, a landscape certification developed by the Lady Bird Johnson Wildlife Center at the University of Texas at Austin, the U.S. Botanic Garden, and ASLA, this magazine’s publisher. The FSC oversees third-party certifiers who administer two forms of certification: forest management and chain of custody. Companies, in return, may gain access to higher-price markets for certified products. Ian Hanna, director of business development for the FSC in the United States, estimates that approximately 5 percent of the forest product market in the United States (this includes everything from cardboard packaging to timber) is FSC certified. This is comparable to the current consumption of certified organic food.

Some seven million hectares of Brazilian forest have been certified by the FSC. Around 59 percent of that land is plantations. The remaining land is “natural.” This includes a spectrum of forest types from relatively old-growth forest to re-naturalized former pasture. The FSC doesn’t explicitly ban the harvest of old-growth forests, Hanna told me, except where they are exceedingly rare. The FSC maintains that the careful management of all types of forests is the best way to protect them. Unmanaged forests receive no protection, Hanna said.

The FSC’s forest management certification is based on 10 principles that address environmental impacts, the rights of indigenous peoples and workers, and maintenance of high conservation value forests, among others. Principle Five requires that harvesting occur at a level that can be sustained permanently. Hanna said at the level of the forest, the sustained yield of wood is strictly met, but he acknowledged that at the level of the species there is “slightly more slack.”

A 2008 study by Schulze, James Grogan, and Edson Vidal in Oryx challenged the assumption that FSC certification guarantees sustained yields. They studied all FSC certificates issued in the Amazon from 1993 to 2005 and found that although the standards are comprehensive, they are administered subjectively. This leads to inconsistencies in the ways standards of harvest operations, forest management, and monitoring are met, they said. If companies in the Amazon were strictly held to all standards required for certification, the researchers concluded that “no companies would currently qualify.” At the time of the study, FSC indicators required that cutting rotations, extractable volumes, and the percentage of seed trees retained must be based on individual species’ biology, but the authors found no evidence of species-level management plans at that time.

In another paper published the same year, in Biological Conservation, the same authors, along with Lentini and Chris Uhl, analyzed the population dynamics of T. impetiginosa and T. serratifolia, on sites harvested under conventional and reduced-impact logging regimes, and projected the impacts of future harvests. Their analysis found that even with reduced logging intensity, it is not possible to sustain production of ipe lumber under current “sustainable” harvest levels. The numbers of trees will continue to decline. The authors recommended further protection of T. impetiginosa and T. serratifolia similar to that which was eventually granted to mahogany. This would involve applying stricter regulations about how much of the species could be harvested from the forest and incorporating silvicultural techniques that could improve chances of seedling survival.

In the experimental plots surrounding the IFT’s Forest Management Center, these silvicultural techniques are being tested. The IFT establishes plantations in forest gaps from seedlings collected from mature trees. Paricá (Schizolobium amazonicum), mahogany, and ipe are planted together to take advantage of their distinct cutting cycles; paricá will be harvested every 30 years, mahogany every 60 years, and ipe every 90 years. We visited two plantations, one planted the year before and one planted 10 years earlier. The young plantation looks like a small garden of neat rows of seedlings. The 10-year-old plantation is barely discernible from the forest around it. Lentini told us that plantation timber, which grows faster than its forest-grown counterparts, tends to be inferior in quality. However, it is these techniques that might one day make the commercial harvest of slow-growing trees, like Tabebuia spp., a more tenable proposition.

The Friends of the High Line opted to complete the project’s second phase with oil-treated teak instead of ipe; the teak was salvaged from industrial and agricultural structures being demolished in Indonesia. The decision followed a 2008 pledge by Mayor Michael Bloomberg, Honorary ASLA, to the United Nations General Assembly that he would reduce New York’s tropical hardwood use by 20 percent. Since then, NYC Parks & Recreation has stopped using tropical wood in park benches. San Francisco, Santa Monica, and Baltimore ban the use of tropical hardwoods completely for municipal projects.

Some problems surround New York’s agenda to reduce its reliance on tropical woods and to source more responsibly harvested wood. When repairing existing structures, replacing unusually strong materials like ipe with alternative materials that have different properties may not work. For example, the Brooklyn Bridge Promenade’s decking of tropical greenheart (Chlorocardium rodiei) can span the structure’s joists, yet replacement with a weaker wood would require an overhaul of the structure, according to New York’s Tropical Hardwood Reduction Plan.

Rot-resistant wood alternatives are hitting the market, including new products like heat-treated and silica-treated lumber. The NYC Tropical Hardwood Reduction Plan suggests using recycled plastic lumber, concrete and clay pavers, or domestic wood products. Black locust (Robinia pseudoacacia) appears to be particularly promising. It is a species native to the United States, it is harder than teak and white oak, yet it is fast growing. Due to its vigorous growth, it has been actively removed in certain contexts and the market for its timber is still nascent. The species was the focus of a 2011 ASLA presentation by the landscape architect Michael Van Valkenburgh, FASLA, and Don Lavender of Landscape Forms, which recently introduced black locust to its palette for site furnishings.

Where FSC-certified ipe might be allowable, it can be difficult to find. At the time of my visit to Belém, two of Timber Holdings USA’s lumber suppliers had access to FSC lumber, but neither had any certified ipe. Teixeira predicted that there would possibly be a small amount of FSC-certified ipe available a few months later, but it seemed like an exception in an otherwise vast market. FSC’s Hanna sees this limited supply of FSC-certified ipe as an indication of the careful management of an uncommon species. He believes that ipe is overused because it is specified by convention, not function. The specification of less common species, Amy Smith of the World Wildlife Fund (WWF) says, has the potential to shift value to the ecosystem rather than the single species and encourage the long-term management of the standing forest. She cites Angelim vermelho (Dinizia excelsa) and curupay (Anadenanthera colubrina) as two tropical hardwood alternatives to ipe. Later this year, the WWF, a longtime partner with the FSC, will be launching a set of tools for designers to find lesser-known timber species and navigate the dense literature on wood selection.

Ipe earned its place in the landscape because it can withstand decades of tough weather, but last fall, Superstorm Sandy revealed the wood is no match for a 13-foot storm surge. At press time, Keating and Rainforest Relief are battling with Avon, New Jersey, and its decision to rebuild its tropical hardwood boardwalk, ravaged by the storm, with ipe. A striking photograph in the New York Times showed the remains of the famous Rockaway Boardwalks—“a hardwood hodgepodge of Angelique, teak, pine, ipe, Cumaru, and greenheart,” as the paper wrote. The crumpled boardwalks triggered debates about whether wood replacements will be able to withstand the more frequent storms that some people expect to result from climate change. Keating sees the devastation of Sandy as an important alarm and sees a direct connection between the destroyed boardwalks and the status of the forests that their wood comes from. “Sandy wiped out boardwalks from Maryland to New York,” he says. “The fact that towns are willing to go back to tropical hardwood is incredible. Materials are not a free ride—they are taken from somewhere, and we forget that at our own peril.”

Jane Hutton is a landscape architecture professor at the University of Waterloo.  Fragments of this paper were developed from “Reciprocal Landscapes: Material Portraits in New York City and Elsewhere,” which was published in JoLA, Issue 15, Spring 2013.