Functional responses
Finally, we found that Functional Richness (Fric), Rao’s quadratic
entropy (RaoQ), and the percentage of parasitoids species significantly
covaried with the vegetation structure, being higher in trees with
higher grass cover and taller herbs, independently of the treatment
(Parasitoids r2 = 0.10, p = 0.045; RaoQ:
r2 = 0.10, p = 0.030 and Fric: 0.15 p = 0.006; Figure
5B, Tables S15-16).
DISCUSSION
Thanks to DNA metabarcoding, we could perform the most thorough analyses
up to date on the effects of livestock on arthropod communities in
Iberian dehesas, the most widespread silvopastoral system in Europe
(Moreno & Pulido, 2009). We detected hundreds of MOTUs in a reduced
time compared to traditional methods. In control trees (livestock
present) vegetation cover and height were lower, and so were the
richness and diversity of arthropods at MOTU and Family level. Grass
cover started to increase just one year after livestock removal.
However, arthropod diversity and taxonomic richness did not peak at
long-term exclosures but at short-term ones. In long-term exclosures
arthropod community composition showed a higher differentiation, both
among them and compared to control and short-term exclosure ones.