5 research outputs found
Exotic fish in exotic plantations: a multi-scale approach to understand amphibian occurrence in the mediterranean region
Globally, amphibian populations are threatened by a diverse range of factors including habitat
destruction and alteration. Forestry practices have been linked with low diversity and
abundance of amphibians. The effect of exotic Eucalyptus spp. plantations on amphibian
communities has been studied in a number of biodiversity hotspots, but little is known of its
impact in the Mediterranean region. Here, we identify the environmental factors influencing
the presence of six species of amphibians (the Caudata Pleurodeles waltl, Salamandra salamandra,
Lissotriton boscai, Triturus marmoratus and the anurans Pelobates cultripes and
Hyla arborea/meridionalis) occupying 88 ponds. The study was conducted in a Mediterranean
landscape dominated by eucalypt plantations alternated with traditional use (agricultural,
montados and native forest) at three different scales: local (pond), intermediate (400
metres radius buffer) and broad (1000 metres radius buffer). Using the Akaike Information
Criterion for small samples (AICc), we selected the top-ranked models for estimating the
probability of occurrence of each species at each spatial scale separately and across all
three spatial scales, using a combination of covariates from the different magnitudes. Models
with a combination of covariates at the different spatial scales had a stronger support
than those at individual scales. The presence of predatory fish in a pond had a strong effect
on Caudata presence. Permanent ponds were selected by Hyla arborea/meridionalis over
temporary ponds. Species occurrence was not increased by a higher density of streams,
but the density of ponds impacted negatively on Lissotriton boscai. The proximity of ponds
occupied by their conspecifics had a positive effect on the occurrence of Lissotriton boscai
and Pleurodeles waltl. Eucalypt plantations had a negative effect on the occurrence of the
newt Lissotriton boscai and anurans Hyla arborea/meridionalis, but had a positive effect on
the presence of Salamandra salamandra, while no effect on any of the other species was detected.
In conclusion, eucalypts had limited effects on the amphibian community at the intermediate
and broad scales, but predatory fish had a major impact when considering all the
scales combined. The over-riding importance of introduced fish as a negative impact suggests that forest managers should prevent new fish introductions and eradicate fish
from already-occupied ponds whenever possible