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Advisor(s)
Abstract(s)
Increasing food production while avoiding negative impacts on biodiversity constitutes one of the main chal-
lenges of our time. Traditional silvopastoral systems like Iberian oak savannas (“dehesas”) set an example, where
free-range livestock has been reared for centuries while preserving a high natural value. Nevertheless, factors
decreasing productivity need to be addressed, one being acorn losses provoked by pest insects. An increased and
focalized grazing by livestock on infested acorns would kill the larvae inside and decrease pest numbers, but
increased livestock densities could have undesired side effects on ground arthropod communities as a whole. We
designed an experimental setup including areas under trees with livestock exclosures of different ages (short-
term: 1-year exclusion, long-term: 10-year exclusion), along with controls (continuous grazing), using DNA
metabarcoding (mitochondrial markers COI and 16S) to rapidly assess arthropod communities’ composition.
Livestock removal quickly increased grass cover and arthropod taxonomic richness and diversity, which was
already higher in short-term (1-year exclosures) than beneath the canopies of control trees. Interestingly,
arthropod diversity was not highest at long-term exclosures (≥10 years), although their community composition
was the most distinct. Also, regardless of treatment, we found that functional diversity strongly correlated with
the vegetation structure, being higher at trees beneath which there was higher grass cover and taller herbs.
Overall, the taxonomic diversity peak at short term exclosures would support the intermediate disturbance
hypothesis, which relates it with the higher microhabitat heterogeneity at moderately disturbed areas. Thus, we
propose a rotatory livestock management in dehesas: plots with increased grazing should co-exist with temporal
short-term exclosures. Ideally, a few long-term excluded areas should be also kept for the singularity of their
arthropod communities. This strategy would make possible the combination of biological pest control and
arthropod conservation in Iberian dehesas.
Description
Keywords
Livestock exclusion Metabarcoding Arthropods Intermediate disturbance hypothesis
Pedagogical Context
Citation
Canelo, Tara, et al. «Effects of Livestock on Arthropod Biodiversity in Iberian Holm Oak Savannas Revealed by Metabarcoding». Journal of Environmental Management, vol. 365, agosto de 2024, p. 121619. https://doi.org/10.1016/j.jenvman.2024.121619.
Publisher
Elsevier