Restoration of a degraded tropical dry forest in Macanao, Venezuela

Tropical forests appear to take longer to recover in dry than in humid areas, thus water has been recognized as a key structuring factor in tropical dry forests (TDF). We examine this hypothesis in arid ecosystems of the Macanao Peninsula, Venezuela. Opencast sand mining is one of the primary economic activities in the region, modifying the soil, degrading biodiversity and ecosystem services, and affecting key plant and animal species. We quantified growth and survival of five native trees (Tecoma stans, Bulnesia arborea, Piscidia carthagenensis, Prosopis juliflora and Cercidium praecox) under eight treatments, combining hydrogel, fertilizer and water. After six months in a nursery, 640 seedlings were planted in 16 field plots of 100 m2 each, two for each treatment. Eight months later, the treatment with the greatest impact on plant growth was hydrogel only; also the most cost-effective option. Our results support the water-limitation hypothesis, and show that improving water supply to seedlings greatly increases their growth and survival. Our experimental design is applicable to the restoration of any TDF where human disturbance has caused a large-scale modification to the ecosystem, preventing the progression of natural succession.

► Active restoration is required in degraded areas at the Macanao Peninsula. ► Seedlings grown in nurseries provide a viable option to recover degraded dry forests. ► Proper water supply is a key factor for plant growth and survival in dry forests. ► Hydrogel provides adequate water supply for plant growth at low costs.