Habitat loss and fragmentation can alter trophic networks and drive biodiversity loss. We examined fragmentation-induced changes to the dietary niche and abundance of a generalist predator, the forest wood scorpion, Cercophonius squama, in an experimentally fragmented landscape. Our study site was the Wog Wog Habitat Fragmentation experiment (NSW, Australia). We aimed to understand how habitat fragmentation impacted the structure and complexity of the invertebrate food web. We examined the response in abundance to fragmentation of C. squama and the impacts of fragmentation on the d15N and d13C isotope ratios present in scorpion tissue to understand how fragmentation altered the invertebrate food web. We predicted that 1) scorpions would decrease in abundance as a result of experimental habitat fragmentation, 2) scorpions would feed on average, at a lower trophic position in experimental fragments compared to controls due to trophic downgrading, and 3) individual variation in scorpion diet would be lower in fragments relative to continuous forest controls.
Results/Conclusions
Experimental forest fragmentation did not alter the abundance of C. squama. The d15N values of scorpions were on average, 1.10‰ and 1.16‰ higher in fragments and matrix, respectively, compared to the continuous forest controls. The isotopic niche of the scorpion, expressed in a d13C and d15N bivariate plane, was greatest in the pine plantation matrix, followed by the experimental fragments and the continuous forest. Our research contributes to other findings from fragmented forest landscapes showing that fragmentation may not impact the abundance of generalist predators. Our research further illustrates the complexity in the response of food webs to fragmentation. In particular, we show that fragmentation might not always drive predictable food web simplification; scorpions in fragments and the matrix, on average, fed at a higher trophic level than in controls. Finally, we show that in fragmented forest landscapes, both fragments and the matrix support diverse invertebrate communities, ultimately contributing to greater individual variation in a generalist predator’s diet than in continuous forest controls.