The potential of Eucalyptus plantations to restore degraded soils in semi-arid Morocco (NW Africa)

Abstract

Key message: Short-rotation forestry using eucalyptus in degraded oak forests in the semi-arid area of NW Morocco can be a useful strategy to avoid further degradation and carbon loss from this ecosystem, but it might be constrained by nutrient and water supply in the long term. Context: Land degradation and deforestation of natural forests are serious issues worldwide, potentially leading to altered land use and carbon storage capacity. Aims: Our objectives were to investigate if short-rotation plantations can restore carbon pools of degraded soils, without altering soil fertility. Methods: Carbon and nutrient pools in above- and below-ground biomass and soils were assessed using stand inventories, harvested biomass values, allometric relationships and selective sampling for chemical analyses. Results: Carbon pools in the total ecosystem were low in the degraded land and in croplands (6–13 Mg ha−1) and high in forests (66–94 in eucalyptus plantations; 86–126 in native forests). The soil nutrient status of eucalyptus stands was intermediate between degraded land and native forests and increased over time after eucalyptus introduction. All harvest scenarios for eucalyptus are likely to impoverish the soil but, for the moment, the soil nutrient status has not been affected. Conclusion: Afforestation of degraded land with eucalyptus can be a useful restoration tool relative to carbon storage and soil fertility, provided that non-intensive forestry is applied.