Planted forests for open coal mine spoils rehabilitation in Colombian drylands: Contributions of fine litterfall through an age chronosequence

•A clear pattern of greater fine litterfall was found at sites with older age of rehabilitation.•High contributions of fine litterfall fractions were associated to high Basal Area and Height stand values.•Rehabilitation activities with vegetation can increase the quality of edaphic substrates. The contributions of organic matter via fine litterfall to the soil were evaluated in three sites that were rehabilitated 7, 10, and 21 years earlier, respectively, located in an opencast coalmine at El Cerrejón (La Guajira, Colombia). We placed forty litterfall traps in four plots at each reclaimed site and in a tropical dry mature forest, which was used as a reference ecosystem. Fine litterfall (including woody material up to 2 cm in length) was collected monthly from October 2013 to November 2014. Values for the highest fine litterfall recorded in the 21-year-old site (2.3 Mg ha−1 year−1) were more than double those recorded in the 7-year-old site (1.1 Mg ha−1 year−1). Soil carbon and nitrogen contents were greater in the rehabilitated sites than in the unrestored substrate. Soil phosphorus (P) increased significantly 7 years after rehabilitation. The high return of organic matter and nutrients via fine litterfall in the three rehabilitated sites suggests that the rehabilitation approach employed in this opencast coalmine was successful in terms of enriching soil organic matter content and nutrient status and that it could serve as a model for the rehabilitation of similarly degraded mining habitats.