Coffee pulp accelerates early tropical forest succession on old fields.
Abstract
Applying nutrient-rich agricultural by-products, such as fruit peels and pulp, to degraded land has been proposed as a strategy to overcome a number of barriers to tropical forest recovery. While such linkages between agroindustry and restoration represent win-win scenarios, practical applications remain largely unexplored. In this case study, we tested coffee pulp as an amendment to catalyze forest succession on post-agricultural land in southern Costa Rica. A 0.5-m-deep layer of coffee pulp was deposited across a 35 × 40-m area and an adjacent similar-sized control plot (no coffee pulp addition) was delineated. Over 2 years, we measured changes in soil nutrients, ground cover, understory vegetation, tree establishment and canopy cover across both coffee pulp and control treatments. Our results show that soil carbon, nitrogen, and phosphorous were substantially elevated in the coffee pulp compared to control treatment after 2 years. Coffee pulp addition significantly altered the ground cover characteristics, eliminating pasture grasses, facilitating establishment of herbaceous plants and increasing the percent area covered by leaf litter. Early-successional trees and shrubs established quickly in the coffee pulp treatment, reaching 30-fold greater mean basal area and 20-fold greater woody stem density (> 1-cm-dbh) compared to the control treatment. Structural metrics showed fourfold greater mean canopy height in the coffee pulp compared to control treatment. Canopy height > 5 m was ~40% in the coffee pulp but was negligible (< 3%) in the control treatment. Our study highlights the significant potential for using agricultural waste, such as coffee pulp, to jump start forest succession on degraded tropical lands and encourages further research to optimize linkages between agroindustry and restoration.