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Question: How does the sowing of native species under different soil treatments contribute to the recovery of gypsum habitats affected by quarrying in Mediterranean environments? \ud \ud Location: Mediterranean gypsum outcrops in Granada (SE Spain; 37 degrees 2' N, 3 degrees 45' W). \ud \ud Methods: We conducted an experimental sowing of native perennial species from gypsum habitats (both gypsophiles and gypsovags) considering two factors: bedding materials and surface treatments. For bedding material we used: gypsum spoil, topsoil addition on gypsum spoil, raw gypsum and topsoil removal. The surface treatments were: control, sowing, sowing plus organic matter and sowing plus an organic blanket. There were five replicates per combination treatment (80 plots in total, of 25 m (2) each). The sowing was performed in Nov 2009. All subplots were monitored to estimate density, richness, survival, growth of seedlings and herbaceous biomass, in two monitoring periods (Jul and Oct). \ud \ud Results: No gypsophiles or gypsovags were found in the control plots (no sowing or surface treatment), and therefore natural succession proved ineffective in the first year. In contrast, sowing was very satisfactory, especially on gypsum spoil, where mean density was of more than 15 individuals m(-2). This result is noteworthy as this material remains after the end of gypsum mining activity. Spreading topsoil over gypsum spoil proved to be no more positive, since it provided not only seeds of target species but also of competitor species. Also, with regard to herbaceous species, this treatment produced a highly significant increase of biomass. The organic blanket increased plant density, whereas the addition of organicmatter had significant positive effects on survival and growth of the seedlings. The global high survival rate is remarkable, especially for the gypsum spoil treatment. \ud \ud Conclusions: We highlight the importance of implementing recovery measures in gypsum habitats. An appropriate selection of seed mixture and density, as well as the use of gypsum spoil (the most favourable bedding material, according the results), is sufficient to ensure presence of the key species. Both technical solutions tested, organic blanket installation and organic matter addition, improved the results in terms of density, survival and growth of the seedlings

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Ononis tridentata L. subsp. crassifolia (Leguminosae) is a narrow endemic plant restricted to gypsum outcrops in south-east Spain. Its habitat and populations are currently threatened by anthropogenic disturbance. Because of the paucity of information concerning its distribution, abundance and response to disturbance, we assessed its status and evaluated the impacts of quarrying, ploughing, grazing and afforestation. Distribution and population size were estimated by field surveys, censuses and mapping. We measured cover, plant volume, fruit and seed production, seed predation and seedling recruitment to asses any effects of disturbance. The species’ area of occupancy is 1.6 km2 and its extent of occurrence 337 km2, in 29 habitat patches and 16 populations between 705 and 1,125 m altitude, and its population size was estimated to be 531,605. Quarrying, ploughing, overgrazing and afforestation negatively affected the species, in this order. We recommend this subspecies be categorized as Vulnerable on the IUCN Red List. A species recovery plan is required, and the ecological restoration of altered areas would mitigate negative effects on the species and improve the overall conservation of gypsum habitats.

The establishment of gypsicolous vegetation of high conservation value on land impacted by quarrying requires restoration measures to overcome constraints imposed by the new landforms created in the process. The aim of this study was to assess the suitability of three standard hydroseeding methods to restore gypsicolous vegetation on quarry spoil slopes under a dry Mediterranean climate. The treatments were as follows: paper cellulose mulch, paper cellulose mulch + organic blanket, and wood fibre mulch, compared against a control. These treatments were tested on two slopes (10–15% vs 60–65%) and two contrasting aspects (north vs south). We evaluated the cover of all plant species 2·8 years after treatment, assessing both target gypsicolous species and non‐target species. Our results showed strong compositional and cover differences between hydroseeded and control plots. Control plots had a low cover of target species with a vegetation composed of early‐successional species that had the potential to hinder target species establishment over time. All hydroseeding treatments improved target vegetation cover, with wood fibre performing best in most situations studied here, 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 were more suitable for the recovery of gypsum vegetation by hydroseeding, compared to northern‐steep slopes where non‐target species developed more readily outcompeting target species. These results will help to guide management decisions to restore gypsicolous vegetation by hydroseeding in disturbed gypsum habitats. Copyright © 2017 John Wiley & Sons, Ltd.

Many studies have reported the phytotoxicity of allelopathic compounds under controlled conditions. However, more field studies are required to provide realistic evidences for the significance of allelopathic interference in natural communities. We conducted a 2-years field experiment in a semiarid plant community (NE Spain). Specifically, we planted juvenile individuals and sowed seeds of Salsola vermiculata L., Lygeum spartum L. and Artemisia herba-alba Asso. (three co-dominant species in the community) beneath adult individuals of the allelopathic shrub A. herba-alba, and assessed the growth, vitality, seed germination and seedling survival of those target species with and without the presence of chemical interference by the incorporation of activated carbon (AC) to the soil. In addition, juveniles and seeds of the same three target species were planted and sown beneath the canopy of adults of S. vermiculata (a shrub similar to A. herba-alba, but non-allelopathic) and in open bare soil to evaluate whether the allelopathic activity of A. herba-alba modulates the net outcome of its interactions with neighboring plants under contrasting abiotic stress conditions. We found that vitality of A. herba-alba juveniles was enhanced beneath A. herba-alba individuals when AC was present. Furthermore, we found that the interaction outcome in A. herba-alba microsite was neutral, whereas a positive outcome was found for S. vermiculata microsite, suggesting that allelopathy may limit the potential facilitative effects of the enhanced microclimatic conditions in A. herba-alba microsite. Yet, L. spartum juveniles were facilitated in A. herba-alba microsite. The interaction outcome in A. herba-alba microsite was positive under conditions of very high abiotic stress, indicating that facilitative interactions predominated over the interference of allelopathic plants under those conditions. These results highlight that laboratory studies can overestimate the significance of allelopathy in nature, and consequently, results obtained under controlled conditions should be interpreted carefully.

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