Coffee waste can boost forest recovery: Study

Coffee pulp, a waste product of coffee production, could be used to speed up tropical forest recovery on post agricultural land, suggests a new study. In the study published in the journal 'Ecological Solutions and Evidence', the team spread 30 dump truck loads of coffee pulp on a 35-40m area of degraded land and marked out a similar sized area without coffee pulp as a control.

"The results were dramatic", said lead researcher Rebecca Cole from the University of Hawai'i in the US. "The area treated with a thick layer of coffee pulp turned into a small forest in only two years while the control plot remained dominated by non-native pasture grasses," Cole added. After only two years, the coffee pulp treated area had 80 per cent canopy cover compared to 20 per cent in the control area. The canopy in the coffee pulp area was also four times taller than that of the control area.

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The addition of the half metre thick layer of coffee pulp eliminated the invasive pasture grasses which dominated the land. These grasses are often a barrier to forest succession and their removal allowed native and pioneer tree species, that arrived as seeds through wind and animal dispersal, to recolonise the area quickly. The researchers also found that after two years, nutrients, including carbon, nitrogen and phosphorous, were significantly elevated in the coffee pulp treated area compared to the control.

For the study, the researchers analysed soil samples for nutrients immediately prior to the application of the coffee pulp and again two years later. They also recorded the species present, the size of woody stems, percentage of forest ground cover and used drones to record canopy cover.