The role of species niche, species dispersal and landscape factors in the assembly of novel woody communities in metropolitan Mediterranean regions
Biological diversity in a global scale has been threaten seriously by anthropogenic disturbances in ecosystems. Changes in land cover and land use affect biodiversity, causing habitat loss and species extinction, or colonization and establishment of new communities. Such effects could happen in an o...
| Autor: | |
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/462039 |
| Acceso en línea: | http://hdl.handle.net/10803/462039 |
| Access Level: | acceso abierto |
| Palabra clave: | Nínxol ecològic Nicho (Ecología) Niche (Ecology) Àrees metropolitanes Áreas metropolitanas Metropolitan areas Mediterrània (Espanya : Costa) Mediterráneo (España : Costa) Mediterranean Coast (Spain) Ciències Experimentals i Matemàtiques 574 |
| Sumario: | Biological diversity in a global scale has been threaten seriously by anthropogenic disturbances in ecosystems. Changes in land cover and land use affect biodiversity, causing habitat loss and species extinction, or colonization and establishment of new communities. Such effects could happen in an outdated way between the time of the disturbance and species extinction or colonization. Landscape history, connectivity between habitat fragments and the dispersion of organism, shapes species diversity and influences extinction and colonization process. On the other hand, exotic plant invasion could drive the assembly of plant community in newly formed forests as a result of changes in land use. The present thesis aims to contribute to the knowledge of the assembly of new woody communities in forests and bushes of the metropolitan region of Barcelona. For this, the legacy of five historical land use trajectories and the environmental factors on the richness, diversity and equity of woody species in shrubland were analyzed. In addition, we evaluated the relationship between environmental and historical factors and species composition (Chapter 3). The results revealed that species richness and diversity are associated with both elevation and historical trajectories of land use, while equity only to elevation. The study did not detect spatial effects attributable to dispersion. The results indicated that both trajectories and environmental factors (niche) equally drive local community assembly, while dispersal seems to play a secondary role. The richness and diversity of species are affected by the use of the soil in the recent past (1956) and the composition by the oldest uses (1900). Additionally, the effect of urbanization on plant community assembly process in new periurban forests (Chapter 4) was evaluated. We explored the relationship between plant species richness and composition (dispersed by vertebrates and non-vertebrates), and forest patches history (pre-existing and recent), landscape pattern (forest connectivity and urbanization), habitat condition (forest, prairie grass, synanthropic, other) and environmental variables. The results showed that landscape habitat and structure are the main drivers of plant community assembly. However, as a side effect of forest history, extinction debt of scrub-meadow species must be considered. In addition, we found a greater colonization of synanthropic species and a credit for colonization of forest species dispersed by vertebrates in recent forests. The assemblage of new forests was characterized by the presence of species of previous habitats, rapid colonization of specialists and an increase of synanthropic species. Finally, the patterns of invasion by exotic plants and the influence of dispersal mechanism, environmental variables and landscape anthropization in these newly formed periurban forests were analyzed (Chapter 5). The presence, richness and abundance of exotic species dispersed by vertebrates and non - vertebrates in recent and preexisting forests were compared, taking into account landscape and environmental correlations. The results showed that metropolitan forests are more invaded than the rest of the province and the exotic flora on these forests are dominated by species dispersed by vertebrates. However, at the regional level a bias was found towards species dispersed by non-vertebrates. Forest fragmentation was associated with the presence, richness and coverage of plants dispersed by vertebrates; while urbanization was related with coverage of species dispersed by non-vertebrates. We suggest an association between forest history and plant dispersion syndromes, with species dispersed by vertebrates in ancient forests. No associations between exotic species composition and environmental factors were found, but not with forest history. The study notes a high degree of invasion of forests by alien species dispersed by vertebrates, which could colonize unaltered forests and persist and even expand throughout forest succession. |
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