Enhancing seedling production of native species to restore gypsum habitats

Abstract

Gypsum habitats are widespread globally and are important for biological conservation. 20Nevertheless, they are often affected by human disturbances and thus require restoration. Sowing and planting have shown positive results, but these actions are 22usually limited by the lack of native plant material in commercial nurseries, and very little information is available on the propagation of these species. We address this 24issue from the hypothesis that gypsum added to a standard nursery growing medium (peat) can improve seedling performance of gypsum species and, therefore, optimise 26 the seedling production for outplanting purposes. We test the effect of gypsum on emergence, survival, and growth of nine native plant species, including gypsophiles 28 (exclusive to gypsum) and gypsovags (non-exclusive to gypsum). We used four treatments according to the proportions, in weight, of gypsum:standard peat, i.e. high-g 30 (50:50), medium-g (25:75), low-g (10:90), and standard-p (0:100).Our results showed that the gypsum treatments especially benefited the 32 emergence stage, gypsophiles as group, and Ononis tridentata as a taxon. In particular, the gypsum treatments enhanced emergence of seven species, survival of 34 three species, and growth of two gypsophiles, while the use of the standard peat favoured only the emergence or growth of three gypsovags. Improving emergence and 36 survival in the nursery can provide a reduction of costs associated with seed harvesting, watering, and space, while enlarging seedlings can favour the 38 establishment of individuals after outplanting. Thus, we suggest adding gypsum to a standard growing medium for propagating seedlings in species from gypsum habitats, 40 thereby potentially cutting the costs of restoring such habitats. Our assessment enables us to provide particular advice by species. In general, we recommend using between 42 25 and 50% of gypsum to propagate gypsophiles, and between 0 and 10% for gypsovags. The results can benefit not only the production of widely distributed species 44 commonly affected by gypsum quarrying, but also of narrow and threatened endemic species that require particularly efficient use of their seeds. In addition, our study 46 shows the importance of using an appropriate growing medium to propagate plants characteristic of special soils such as gypsum soils. 48

Trade-Off between Facilitation and Interference of Allelopathic Compounds in Vegetation Recovery: The Case of Rosmarinus officinalis in Degraded Gypsum Habitats

“…The emergence of O. tridentata subsp. crassifolia was very low in all the treatments probably due to its commonly low germination rate (≤20%) [ 46 , 47 ], together with the low ratio of sown seeds for this species compared to the others. L. subulatum presented an especially low emergence rate in those treatments somehow influenced by a rosemary plant, whereas it found its peak of emergence in the “Bare Soil” treatment, suggesting that this species is especially sensitive to competition and allelopathy interference.…”