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Ecological restoration in degraded drylands: The need to improve the seedling quality and site conditions in the field

Abstract:

Ecological restoration represents an important tool for combating land degradation and increasing ecosystem resistance and resilience to disturbance, thus favoring the recovery of functions and services. Degraded drylands constitute very harsh conditions for the natural regeneration and rangeland restoration of the ecosystems. Scarcity of rainfall after planting, inappropriate seedling quality and unfavorable hydro-physic and chemical characteristics of the soil often affect the success of ecological restoration projects. Therefore, there is a need to improve ecological restoration techniques in degraded drylands. In this paper we analyze innovative nursery and field techniques oriented to reduce outplanting stress on the basis of the researcher experience of the CEAM Foundation's Forest Restoration Programme1 and the Ecosystems Management and Biodiversity group in the University of Alicante's Department of Ecology2 though several RTD projects funded by the Valencia Regional Government, the Government of Spain and the European Commission. In the nursery, the main research lines are directed towards improving seedling quality, especially its resistance to water stress, by means of the use of containers gauged to the different root growth patterns of the species, the use of hydrogel to improve the water holding capacity of the substrate and reduce post-planting stress, the use of drought preconditioning to induce mechanisms for drought resistance, the use of fertilization according to field conditions and target seedlings for restoration projects and the use of growth regulators to control the biomass distribution within the seedlings. Other research lines are focused on ameliorating site conditions in the field, particularly soil and microclimatic conditions, by using: microcatchments to improve runoff harvesting and soil water availability to seedlings, deeper planting holes according to species growth patterns, treeshelters to reduce environmental stress, hydrogels to improve soil water-holding capacity, organic amendments like biosolids to improve soil fertility, and biotic interactions to facilitate seedling establishment. Then, we present the demonstration project on the restoration and management of semi-arid areas affected by desertification in Albatera (Spain) as an example of the implementation of these innovative techniques. This project has shown that increased technological investment in forest restoration ensures acceptable results in seedling survival and growth, and gradual ecosystem recovery. Finally, the challenges and opportunities for ecological restoration in dryland are discussed on the basis of the results shown and future climate projections. © 2009 Nova Science Publishers, Inc. All rights reserved.