Coffee pulp – a waste product that makes up more than half the coffee harvest – could be the secret ingredient to return rainforests to areas where they were destroyed, according to a new paper in the journal Ecological Solutions and Evidence. The evidence so far based on one small study area, but the effects there were astonishing.
Tragically, humanity gets little benefit from chopping down Earth’s richest ecosystems. Tropical rainforests grow in areas of abundant sunlight and water, but their soils are usually poor, so agriculture on former rainforest land seldom lasts long. That provides opportunities to bring the forests back, but that is often a slow process.
Dr Rebecca Cole of the University of Hawai’i is trying to speed things up, conducting experiments on a patch of former Costa Rican rainforest cleared for a coffee plantation in the 1950s. Non-native grasses have taken over, interfering with forest recovery.
The team dumped a layer of coffee pulp 0.4-0.5 meters (1.31-1.64 feet) thick on an area of 35 by 40 meters (115 by 132 feet) of this land. They didn’t try to replant either it or a neighboring control area, instead allowing plant seeds to arrive via animals and the wind. "The results were dramatic,” Cole said in a statement. Two years later, she reports in the new study, the treated area was 40 percent covered by trees more than 5 meters (16 feet) high, whereas the control had less than 3 percent cover. Woody stem density was also 20 times higher on the treated patch. The trees were a healthy mix of species with both wind and animal dispersed seeds.
Besides asphyxiating invasive grasses, the pulp at least tripled soil concentrations of carbon, nitrogen, phosphorus, and iron.
"This case study suggests that agricultural by-products can be used to speed up forest recovery on degraded tropical lands. In situations where processing these by-products incurs a cost to agricultural industries, using them for restoration to meet global reforestation objectives can represent a 'win-win' scenario." Dr Cole said.
It’s certainly too early to conclude that one of the world’s most serious problems is solved based on a single test area smaller than a baseball infield. Cole cautions the benefits may be restricted to flatlands, where the pulp won’t be washed away by the area’s 3.5 meters (10 feet) of annual rain.
Nevertheless, the prospects are exciting. Currently, coffee is marketed as “rainforest friendly” purely by doing no harm. Although better than beans from cleared land, purchasing this coffee doesn’t actively help the environment (except perhaps the buyer’s household). Widespread adoption of Cole’s idea, however, could offer coffee drinkers a warm inner glow knowing the more they drink, the more land gets restored.
Besides trying more diverse locations, Cole is keen to see if coffee pulp provides the land a special buzz, or if other forms of agricultural waste work just as well. Four years ago it was revealed orange peel had a similarly restorative effect on another patch of cleared Costa Rican forest. However, an interruption in monitoring of the orange peel site means that project needs repeating even more than the Cole’s work.