Key Takeaways - Learn About Tree Materials
- Tree materials preceded plastic, and they can displace it again. For millennia, humanity relied on trees for everything from shelter to insulation, adhesives, and more.
- Unlike plastic, trees regenerate and provide materials for centuries. Cork oaks regenerate their bark for about two centuries, rubber trees yield for 25 to 30 seasons, and carnauba palms produce for up to 50 years without one being felled. Petroleum can only be pulled out of the ground once.
- Waiting between harvests is what makes them renewable. Portuguese law allows a cork oak to be stripped only once every nine years. Where no limit is enforced the resource runs down and as wildfire and deforestation increase threats, restoring the land where these trees grow is critical.
Every NASA spacecraft that has landed on Mars got there behind a heat shield made partly of tree bark — a cork and silicone ablator that originated with the Viking landers of the 1970s, according to NASA. Cork remains a critical element of the core, and still line the core stage engine section of the Space Launch System, where four RS-25 engines produce two million pounds of thrust.
The trees those sheets come from grow primarily in Portugal, and are some of the most protected in the world. A cork oak cannot be stripped until its trunk reaches 70 centimeters around, which takes about 25 years, and Portuguese law forbids returning to the tree to strip cork for nine years after that. Only from the third harvest, around the tree's 43rd birthday, is the cork good enough for a wine bottle (or NASA spacecraft). Over roughly two centuries, a cork tree will support about 15 harvests.
Harvesting materials from living trees happens on a cycle set to the rate at which the plant can replace what's removed. Cork’s cycle is strictly enforced to nine years but other materials including latex, resin, kapok floss, rattan cane, and carnauba wax come off living plants on the same logic: taking just enough, infrequently enough, so the tree can keep producing more. These tree substances have been used by Indigenous communities for millennia, providing materials for packaging, insulation, adhesives, bedding, and fill for centuries. They provided income sources too as the market demand grew.
Then came plastic.
How plastic became the preferred material
Petroleum-based materials overtook nearly all of those markets over the course of the 20th century, category by category, on both price and durability. Kapok, which comes from the seeds of a tropical tree, filled life jackets and aviation clothing until, as researchers writing in Plants recorded, "in the 1960s, as a result of the massive production of synthetic fibers, the kapok trade declined substantially." Rosin lost ground the same way — petroleum resins "have gained dominance over natural rosin in some countries," FAO noted, though rosin held its edge on certain chemical properties.
The world now produces roughly 460 million metric tons of plastic a year, a figureThe Organisation for Economic Co-operation and Development projects could climb 70% by 2040 without stronger policy, and making it accounts for about 5.3% of global greenhouse gas emissions — more than aviation and shipping combined. The pressure runs the other way, too. WWF has warned that plastic stoppers and screwtops taking market share from cork could strip the economic value out of cork oak landscapes, leading to "conversion to other uses, abandonment, degradation, and finally loss." The market for the material is part of what keeps the forest standing.
How forest restoration supports regenerative tree materials
Cork comes out of a landscape the Portuguese call the montado — open cork oak woodland with cattle and crops working the ground underneath, the trees spaced wide enough to let the light through. Young oaks come up readily under an open canopy, but once scrub closes over the ground they nearly stop: 3.6 seedlings per square meter in open woodland against 0.1 in shrubland, researchers reported. Southern Portugal lost 31,312 hectares of montado between 2006 and 2018, mostly to wildfire and to trees dying of disease and pests, a 2026 study in Agroforestry Systems found. A landscape that renewed itself for centuries no longer does, which puts replanting efforts in the routine maintenance column.
This is the work One Tree Planted's projects provide. In Portugal, our work in Leiria has planted 1.3 million native, fire-resilient trees across nearly 1,000 hectares of the Pinhal de Leiria — a 700-year-old coastal pine forest that lost 86% of its area to a single wildfire in October 2017, in 24 hours — and cork oak is among the key species going in, alongside maritime pine and strawberry tree.
In Acre, Brazil, we’re helping to restore 150 hectares of deforested land with 150 families planting 300,000 seedlings in agroforestry systems — trees and crops on the same ground, which is the arrangement nearly every material in the first half of this list comes out of.
