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Universidad de Granada (2018)

Restoration of gypsum habitats affected by quarrying : Guidance for assisting vegetation recovery

Ballesteros Jiménez, Miguel

Titre : Restoration of gypsum habitats affected by quarrying : Guidance for assisting vegetation recovery

Auteur : Ballesteros Jiménez, Miguel

Université de soutenance : Universidad de Granada

Grade : Doctorado en Biología Fundamental y de Sistemas 2018

Gypsum soils in drylands support important habitats for conservation of unique specialised flora that must be preserved. Gypsum habitats are destroyed, fragmented and degraded by human activities, and several limitations challenge the recovery of gypsum vegetation. However, the restoration of vegetation after disturbance has only been partially addressed. The aim of this thesis is to study several methods to assist in the recovery of gypsicolous vegetation affected by quarrying in SE Spain under Mediterranean conditions. We assessed habitat current conditions and studied local native plant communities to establish references for restoration, addressed the effect of gypsum on plant development, determined the suitability of various soil treatments and revegetation methods, and explored the potential of lichen translocation to recover gypsum biological soil crusts. We focused on characteristic gypsicolous species included in the habitat of Community interest 1520 ‘Iberian gypsum vegetation, Gypsophiletalia’ affected by quarrying in centre-west Granada province (SE Spain). In Chapter 1 we determined the distribution, abundance and response to disturbance of the narrow endemic Ononis tridentata subsp. crassifolia to assess its conservation status. Habitat depletion from quarrying, assuming the projected exploitation plan suggests this subspecies should be categorized as Vulnerable and that its recovery and the ecological restoration of altered areas are required. In Chapter 2 and 3 we tested the effect of gypsum at different stages of plant development under controlled conditions, with the final aim of gaining insight into the propagation of a selection of native species for habitatrestoration purposes. Gypsum improved the efficiency in propagation of O. tridentata subsp. crassifolia and other important species in gypsum habitats. In Chapters 4, 5 and 6 we assessed the suitability of planting and sowing methods on four substrates (raw gypsum, gypsum spoil, topsoil or marls) alone or combined with surface treatments (organic matter addition or organic blanket overlays). Raw gypsum has higher cost but remarkable benefits for gypsophiles, particularly for O. tridentata subsp. crassifolia, what must be considered in the design of restoration plans. Topsoil increases plant cover, but should not be routinely used to restore gypsicolous vegetation. The conclusion is reached that gypsum spoil is the most recommendable bedding material for the general habitat restoration due to its low cost, wide availability, and satisfactory establishment of target vegetation. Building on this finding, in Chapter 7 we assessed the suitability of three hydroseeding methods to restore gypsicolous vegetation on quarry spoil slopes considering the effect of slope and aspect. Hydroseeding with wood fibre is recommendable in most situations, alternatives being the cheaper but less effective paper mulch on shallow slopes, or the more expensive paper mulch + blanket on steep slopes in case of high erosion risk. Shallow and southern-steep slopes are more suitable for the recovery of gypsum vegetation by hydroseeding, compared to northern-steep slopes where target species are outcompeted by non-target species. In Chapter 8, we tested how a selection of adhesives could improve translocation of a representative gypsum lichen-species to quarry spoils in rainfall-simulation and field experiments. We found making quarry-spoils wet allowed thalli to remain longer in place after translocation without compromising lichen vitality. This thesis contributes to a better restoration of gypsicolous vegetation affected by quarrying and improves the understanding of plant life on gypsum that will help to develop future programs for the management of gypsum habitats.


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Page publiée le 30 janvier 2019