Synergistic strategies for enhancing plant survival in arid land restoration

Abstract

Introduction: The slow recovery of native dryland vegetation caused by extreme temperatures, limited water and nutrient availability, and intensified by grazing makes its ecological restoration particularly challenging. In this context, facilitation among plant species plays a key role in improving microenvironmental conditions and providing protection against herbivory. Objectives: We experimentally explore the combined effects of four key factors influencing plant establishment in overgrazed drylands: facilitation among species, water and nutrient supplementation, and grazing exclusion. We hypothesized that subsidizing the limiting factors (water and nutrients), removing the disturbance, and enhancing facilitation among species, would synergistically improve vegetation establishment. We also assessed whether successional type of species (i.e. early, intermediate, and late) influenced species responses, according to their life history traits, expecting higher survival in early species than in the rest, and stronger facilitation between species of contrasting successional type (e.g. early–late) than between more similar ones (e.g. early–intermediate). Methods: We evaluated facilitation effects among species (species associations and nurse effects), water addition (hydrogel), nutrient supplementation (organic fertilization), and grazing exclusion (individual protection) on the survival of transplanted plants of several species. Results: Plant survival was highest when combining water and nutrient addition with grazing exclusion. Nurse species significantly improved survival rates, regardless of their successional type of species. Early successional species showed greater survival than intermediate and late species. Conclusion: The synergistic effects of subsidizing limiting factors and disturbance removal allow plants to better absorb and allocate resources to growth, enhancing vegetation recovery. Restoration efforts should focus on early and intermediate successional species for revegetation, while assigning conserving actions on late successional species. Implications for Practice: In dryland ecosystems, effective restoration could be achieved by subsidizing the limiting factors that restrain vegetation growth, enhancing interspecific facilitation, and removing disturbances, particularly overgrazing. These strategies are nature-based solutions for restoration practices. The hydrogel and organic fertilizers or amendments are practical, available, and cost-effective tools. Facilitation is a key process in active restoration that can be enhanced by selecting species according to their successional type: using early and intermediate species for revegetation purposes, and late successional species as nurses. The removal of grazing remains the greatest challenge, requiring the implementation of sustainable livestock management practices.