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Drylands are among the most threatened ecosystems in the world because of the effects of global change and because they are not particularly resilient. Regeneration after disturbance is quite slow and secondary succession can be delayed to the point of nearly stop. This is exacerbated when the community is strongly dominated by a single species able to quickly respond after disturbance. One example of such monospecific dominance is the colonization of abandoned fields in SE Spain by an early successional and native tussock grass, Lygeum spartum, that seems to halt succession.Here we tested the competitive ability of Lygeum against Salsola oppositifolia, a shrub species that can be found interspersed with Lygeum in mid‐successional stages, and assessed how plant–soil interactions mediate the outcome of plant–plant competition. To do so, we sowed seeds and grew plants of Lygeum and Salsola in either intra‐ or interspecific competition under controlled conditions using sterile field soils inoculated with either live (i.e., with micro‐organisms) or sterile soil extracts from the understories of either Lygeum or Salsola. Soil nutrient content, seed germination rate, and shoot mass growth were determined after 5 months, and soil bacterial communities were characterized by sequencing.Lygeum soil micro‐organisms and soil properties, such as the high content of N and organic matter, enhanced seed germination rate of Lygeum individuals. By contrast, Salsola adults outperformed Lygeum when growing in interspecific competition.Synthesis. The enhanced competitive ability of Lygeum, which was mediated by soil micro‐organisms, may lead to complete dominance of Lygeum in the plant community right after abandonment of agricultural fields. However, when the plant community is already developed, Lygeum would be unable to enforce such dominance. We conclude that positive plant–soil feedbacks combined with certain plant traits such as clonal growth support the strong resilience of Lygeum and allow for its dominance in extreme habitats. [ABSTRACT FROM AUTHOR]

Aims: Human activities can dramatically alter natural plant communities which, after disturbance cessation, undergo secondary succession. In arid environments plant succession is quite slow, and its link to the carbon (C) cycle is not well known. We assessed changes in C balance on a semiarid plant community along a chronosequence spanning ca. 100 years after land abandonment in an arid environment in SE Spain to examine temporal changes in C following human disturbance.Methods: We selected 5 individuals of the dominant plant species along five plant community stages differing in the time since land abandonment occurred, and we used a closed-chamber infrared gas analyzer method to estimate the contribution of whole plants and bare soil to community C exchange. We estimated CO2 fluxes for each plant community stage and calculated temporal differences along the chronosequence.Results: Plant community composition and plant cover changed throughout the chronosequence. Carbon balance was related to changes in plant photosynthesis and plant and soil respiration along the chronosequence. Overall, community C exchange shifted from source to sink as plant colonization progressed. It took 65 years for the system to recover the equivalent C sink capacity of the undisturbed site.Conclusions: Recovery of arid plant communities after land abandonment may enhance long-term C sequestration and significantly contribute to C balance at the global level. [ABSTRACT FROM AUTHOR]