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The impact of habitat degradation on seed dispersal networks: Implications for habitat management in Montado forests
Başlık:
The impact of habitat degradation on seed dispersal networks: Implications for habitat management in Montado forests
Yazar:
Timóteo, Sérgio José Antunes, author.
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (172 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-09C.
Özet:
In this thesis I use a network approach to study seed dispersal by ants and birds in a traditional agricultural landscape of Portugal: the Montado. Human induced damage to natural habitats has become an area of considerable concern and one of the main causes of damage is farming. During the 20th century a fundamental shift has occurred from low input techniques in synchrony with natural constraints, to intensive management with a disruptive impact on ecosystems. The Montado provides examples of both these extremes and I use the range of habitats it hosts to explore the effect of disturbance on seed dispersal networks. In my first chapter I look at the overlap between seed dispersal by ants and birds. The groups have a minimal overlap in the species dispersed, thus having a complementary function. The species assemblage of both guilds changes as land management changes. In my second chapter I focus on seed dispersal by ants along a gradient of disturbance caused by land use, ranging from a complex forest with low human intervention, to grazed forest and crop fields. The effects were observed at the level of network structure, and mild perturbations improved the provision of this ecosystem function. In my final data chapter I present the results of a field experiment which compared the effect of the removal of an ant species from experimental plots to unmanipulated control plots; the experiment being replicated in three habitats. The networks showed an extraordinary ability to withstand extreme perturbations and retain functionality. The field data are compared to in silico simulations of species removal and while the models predict the loss of rare species, they overestimate the impact of species removal on seed dispersal and network robustness. The results are presented in the context of the conservation and utilization of the Montado.
Notlar:
School code: 5892
Tüzel Kişi Ek Girişi:
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(691223.1) | 691223-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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