Nature-based solutions can significantly contribute to restoration projects in areas affected by desertification processes, where they are necessary for reversing land degradation. Currently, one innovative solution is The Cocoon™, which has been designed as a new ecotechnology for improving seedling establishment. The Cocoon consists of a doughnut-shaped container made of recycled cardboard that provides water and shelter at least during the first year of a seedling, which is the most critical for plant establishment.

To determine the effectiveness of this ecotechnology under different conditions, the Cocoon was tested on a variety of soils, climates, vegetation, and land uses. Six planting trials were performed in Spain and Greece, which covered a range from humid to arid climates. With the objective of studying its functionality, the survival of the seedlings, their vigor, and growth were monitored for 2 years.

Compared with conventional planting systems, the Cocoon has effectively increased seedling survival, especially under dry growing conditions (low rainfall, soils with low water holding capacity). The Cocoon also allowed for higher growth of some species (olive trees, holm oaks, and Aleppo pines). Moreover, a positive correlation between the rainfall on the site and the biodegradation degree of the Cocoon device was observed. Overall, the Cocoon becomes more efficient in arid climates or adverse growing conditions.

As a conclusion, the Cocoon technology proved useful for reforestation in drylands. In general, conventional plantations showed higher mortalities and relatively lower vigour rates than planting sites using this ecotechnology. The direct and indirect water supply, the mitigation of plant competition around the seedling, the reduction of evapotranspiration, and the microcatchment effect, create a suitable set of conditions for improving the physiological state of plants, which increases their survival.

However, a case-per-case evaluation is needed before deciding on this technology. Cocoons have an added advantage when planting site conditions impose more drought stress (lower rainfall, sandy textured soils with poor water retention), and/or when tree species used are less adapted to drought stress in the early stages of development. However, Cocoons are less competitive than common techniques for planting in soils with high water retention capacity, or in Mediterranean humid climates, or for planting drought-tolerant species. Small differences in survival and growth, combined with higher costs of planting with Cocoons, make this ecotechnology less interesting in these situations.