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Web Ecology An open-access peer-reviewed journal
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Volume 18, issue 1 | Copyright
Web Ecol., 18, 67-79, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Standard article 26 Apr 2018

Standard article | 26 Apr 2018

Are post-dispersed seeds of Eucalyptus globulus predated in the introduced range? Evidence from an experiment in Portugal

Ernesto Deus1,2, Joaquim S. Silva2,3, Hélia Marchante3,1, Elizabete Marchante1, and Catarina Félix3,2 Ernesto Deus et al.
  • 1Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal
  • 2Centre for Applied Ecology “Prof. Baeta Neves”, InBIO Associate Laboratory, School of Agriculture, University of Lisbon, Tapada da Ajuda, 1349-017 Lisbon, Portugal
  • 3Coimbra Agriculture School, Polytechnic Institute of Coimbra, Bencanta, 3045-601, Coimbra, Portugal

Abstract. Plantations of Eucalyptus globulus Labill. have been expanding rapidly worldwide. The species is considered invasive in several regions. While in the native range, post-dispersal seed predation is known to severely limit eucalypt recruitment, there is no experimental evidence of seed predation in the introduced range. We hypothesised that E. globulus seeds largely escape predation in Portugal, which may explain its prolific recruitment in some locations. We tested this hypothesis in central Portugal by exposing E. globulus seeds to the local fauna. For comparison purposes, we also used seeds from locally common species: Acacia dealbata Link (alien, larger, elaiosome-bearing seeds) and Cistus salviifolius L. (native, similarly sized seeds). We installed 30 feeding stations across three study sites, each one dominated by one study species. Each feeding station featured four feeders with different animal-access treatments: invertebrates; vertebrates; full access; no access (control). We placed five seeds of each plant species every day in each feeder and registered the number of seeds missing, eaten and elaiosome detached over 9 summer days.

Eucalyptus globulus seeds were highly attractive to fauna in the three sites. Nearly half of E. globulus seeds were predated or removed, thus contradicting our hypothesis. Surprisingly, E. globulus and A. dealbata seeds were used by animals in similar proportions and C. salviifolius seeds were the least preferred. Vertebrates were the predominant seed predators and preferred the alien seeds. Invertebrates used all seed species in similar proportions. We found spatial variation regarding the predominant type of seed predators and the levels of seed predation according to the following patterns: predominance of vertebrates; predominance of invertebrates; negligible seed predator activity. Locations with negligible seed predation were abundant and scattered across the study area. Such spatial variation may help to explain the heterogeneous recruitment patterns of E. globulus seedlings found in previous studies.

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This study, conducted in central Portugal, shows that Eucalyptus globulus seeds are highly attractive to local fauna, including ants and rodents. Surprisingly, E. globulus seeds were as attractive as the exotic Acacia dealbata seeds and more attractive than the native Cistus salviifolius seeds. However, locations with negligible seed predation were abundant across the study area, which may help to explain the heterogeneous recruitment patterns of E. globulus seedlings found in previous studies.
This study, conducted in central Portugal, shows that Eucalyptus globulus seeds are highly...