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Universidade de Coimbra (2019)

Bridging the roles of seed dispersal and plant mycorrhizal interactions as drivers of ecosystem structure and function

Correia, Marta Raquel Cardoso Lopes

Titre : Bridging the roles of seed dispersal and plant mycorrhizal interactions as drivers of ecosystem structure and function

O papel conjunto dos dispersores de sementes e dos fungos micorrízicos na estrutura e funcionamento dos ecossistemas

Auteur : Correia, Marta Raquel Cardoso Lopes

Université de soutenance : Universidade de Coimbra

Grade : Doutoramento em Biociências, na especialidade de Ecologia 2019

Résumé partiel
Mutualistic interactions like those established between plants and seed dispersers or mycorrhizal fungi are key drivers of plant population dynamics and ecosystem functioning. Seed dispersal is a crucial ecosystem function that allows plants to escape high mortality rates near the parent plant, occupy newly available niches, and expand their distribution range. On the other hand, mycorrhizas are ubiquitous mutualistic interactions between fungi and plant roots, which increase the uptake of water and mineral nutrients, protect plants from herbivores and pathogens, and improve their overall fitness. Despite their importance for plant colonisation and establishment, seed dispersal and mycorrhizal interactions have rarely been explored together. Advancing our understanding of the diversity and functioning of mutualisms is particularly important in the current scenario of rapid environmental degradation because mutualism failure could accelerate the effects of global change on biodiversity loss and ecosystem disruption. Thus, the main goal of this thesis was to explore the potential synergies and trade-offs between two essential mutualisms for plant recruitment, mycorrhizas and seed dispersal, and their joint implications for species distribution and ecosystem functioning. Different approaches were used : large community-level field studies, a review and analysis of information from large databases, laboratory work and greenhouse experiments. Ecological networks were used to evaluate the effectiveness of ecological restoration and to explore the intricacies between below- and aboveground interactions using data from Gorongosa National Park – Mozambique (hereafter Gorongosa), a tropical region of high biological and ecological diversity yet poorly studied. Seed dispersal has severely deteriorated in many ecosystems due to the current defaunation crisis. Despite this, there is virtually no information on how large-scale refaunation efforts can effectively reinstate seed dispersal service. A clear case of defaunation occurred in Gorongosa where a long-lasting war drove most large animals to the verge of extinction until a restoration project was initiated in 2004. One of the key actions of this project was the construction of a large (c. 62 km2) fenced area to protect wildlife from poachers and predators.

Mots clés  : diversity ; ecological interactions ; co-dispersal ; ecological networks ; Gorongosa ; mycorhizal fungi ; seed dispersal ; refaunation ; diversidade ; Interações ecológicas ; co-dispersão ; redes ecológicas ; Gorongosa ; fungos micorrízicos ; dispersão de sementes ; refaunação

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Page publiée le 22 mars 2021