Assessing contributions of deterministic versus stochastic processes to local species assembly: A field experiment with annual plant-dominated communities in gypsum systems
1.The long-standing debate around the processes involved in species assembly has generated a conceptual gradient from deterministic to stochastic postulates. Environment selects traits to determine the species that ultimately participate in realized assemblages. However, neutral ecological processes...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | RUIdeRA. Repositorio Institucional de la UCLM |
| OAI Identifier: | oai:ruidera.uclm.es:10578/47732 |
| Acceso en línea: | https://doi.org/10.1111/1365-2745.70277 https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2745.70277 https://hdl.handle.net/10578/47732 |
| Access Level: | acceso abierto |
| Palabra clave: | Biological soil crusts Environmental filtering Functional diversity Macrochloa tenacissima Perennial tussocks Plant assemblage Secondary seed dispersal Seed availability Trait-based analysis |
| Sumario: | 1.The long-standing debate around the processes involved in species assembly has generated a conceptual gradient from deterministic to stochastic postulates. Environment selects traits to determine the species that ultimately participate in realized assemblages. However, neutral ecological processes (e.g., random seed dispersal, demographic stochasticity) can also lead to species co-occurrence in the community. Despite the current consensus that both filtering and unpredictable events drive the organisation of communities, little information is available regarding the actual contribution of each.2.We experimentally analysed the contributions of both functional filtering and stochasticity (i.e., lack of trait selection) to assembly processes at a fine spatial scale in a dryland gypsum annual plant-dominated community by evaluating the effects of seed availability (natural soil seed banks vs. seed-free soil) and main biotic filters (biocrusts vs. perennial tussocks) on realised assemblages. Species richness, cover, diversity, and functional properties were measured based on major plant traits defining fundamental life strategies in assemblages during four consecutive years.3.Biotic scenarios decisively affected community features. Biocrusts substantially promoted richness and productivity, whereas perennial tussocks restrained assemblage complexity in their vicinity. However, other than some weak filtering effects on maximum plant height and leaf dry matter content, the experimental treatments did not clearly select for either functional or compositional patterns in the community during four consecutive annual assembly events, which matched an unusual spring rainy period.4.Synthesis. Stochastic processes linked to active secondary, horizontal seed movements may play a prominent role in driving local species assembly at a fine spatial scale. Dryland gypsum soil systems have been described as harsh environments that impose strong deterministic filtering effects during plant assembly. However, even in restrictive, environmentally unpredictable habitats, the weightings of deterministic vs. stochastic processes can shift, making stochasticity an eventual force of species coexistence contributing to the maintenance of diversity in the regional pool. Importantly, our results suggest that environmental filters would operate not only through a spatial but also through an intensity hierarchy, in which the intensity of the local biotic filtering depends on that of the regional abiotic one. |
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