Growing cardamom impacts forests for decades

Over 25 years after people stopped growing cardamom in Sri Lanka's Knuckles Forest Reserve (KFR), the spice crop is still having an impact on the forest, according to a recent study in Forest Ecology and Management. The clearing of understory plants and the use of fertilizers continue to shape the forest in the protected area. Cardamom is grown in the shade of the rainforest canopy and so does not require deforestation like other crops. However, often forest vegetation beneath the canopy is cleared. In Knuckles Forest Reserve, researchers found a lower density of plants and different species in the cardamom crop forests versus untouched forests even though the crop was banned in the area since 1985. "We conclude that cardamom cultivation results in a net loss of tree stems through weeding and opening of the canopy to promote cardamom production," the scientists write. The researchers also found lingering changes to the soil. They measured higher levels of phosphorous and exchangeable potassium in the soil where cardamom used to grow, linking them to the use of fertilizers for the crop. But pesticides are another concern: a study last year in Kerala, India found water and soil contaminated with pesticides due to cardamom production, including DDT and mercury. For Knuckles Forest Reserve, which is home to over a thousand flowering plant species and nearly 250 vertebrates, the researchers recommend action to "mitigate [the] effects" of past cardamom production.