Abstract
The rewilding of abandoned agricultural lands opens up opportunities for the recovery of forest ecosystem extent. Frugivorous animals not only take part in the regeneration of unaltered forests, but leave a visible footprint in restoring areas in the form of the number and spatial distribution of new trees recruited from dispersed seeds. Nevertheless, their contribution is conditioned by how environmental factors affect both the patterns of seed dispersal and the fate of post-dispersal regeneration stages throughout the whole ecosystem. Here, we evaluated the role of avian seed dispersers in tree regeneration in woodland pastures resulting from anthropic deforestation. Using an integrative approach, considering the different tree regeneration stages, we dissected the ways in which forest loss conditioned the contribution of frugivores. Habitat structure influenced bird activity, mainly restricting seed dispersal to forested areas. Tree recruitment was severely reduced during early regeneration stages, but maintained the initial forest-biased spatial distribution. However, the presence of scrub in deforested areas, which protect against grazing at late regeneration stages, drastically increased the relevance of tree recruitment outside the forest. Frugivorous birds made a significant contribution to tree regeneration in the woodland pastures under study. The interplay between seed dispersal by birds and the protective role of scrub was fundamental in facilitating the recolonization of deforested areas. If we wish to encourage this natural reforestation, we will need to preserve populations of frugivorous birds while favoring landscape configurations that encourage seed dispersal outside the forest and species that promote tree establishment (like nurse scrubs).
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Acknowledgements
We thank C. Guardado, J. Rodríguez, R. Pérez, and D. O. Pastene for technical support and R. Lendrum for linguistic advice. We are also grateful to K. With and three anonymous reviewers who provided helpful suggestions to improve the manuscript. Field work was conducted with the permission of the Wildlife Service of Asturias. Funding was provided by the Spanish Government and the European Social Fund (FPI BES2009-25093 Grant to DM and CGL2008-01275, CGL2011-28430, and CGL2015-68963-C2-2-R Grants to DG).
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DM and DG contributed equally to the conception and the design of the study. DM performed the research and the analysis of the data, and wrote the manuscript. DG contributed substantially to the research and the writing.
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Additional information on sampling methodologies (DOC 910 kb)
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Spatial Simultaneous Autoregressive models (DOC 88 kb)
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Direct, indirect and total effects estimated in Structural Equation Models (DOC 69 kb)
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Martínez, D., García, D. Role of Avian Seed Dispersers in Tree Recruitment in Woodland Pastures. Ecosystems 20, 616–629 (2017). https://doi.org/10.1007/s10021-016-0043-6
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DOI: https://doi.org/10.1007/s10021-016-0043-6