Fig 1.
Study area and explanatory variables.
a) Spatial distribution of the 36 selected cells in the city of Rome, with indication of the: b) landscape, and c) local scale. The centroid of the cell is the study site where traps were placed. Maps obtained from OpenLayers Plugin, QGIS.
Table 1.
Description and statistics (mean, median and range) of the explanatory variables considered in the study.
Table 2.
Results from the generalized linear models testing the effect of the explanatory variables on: a) species richness, b) abundance, and c) evenness of sphecids and tachinids.
Only significant results after a backward stepwise model selection procedure (P < 0.05) are reported.
Fig 2.
Effects of local scale variables.
Plots showing the relationship between the distance from the street and: a) the evenness of sphecids, and b) the species richness and c) the abundance of tachinids. Panel d shows the effect of the coverage in buildings in a 50 m buffer on the species richness of tachinids. Only significant results were presented (P < 0.05). Plots include expected value (black line), and 95% confidence interval (gray shading).
Fig 3.
Effects of landscape scale variables: Percentage of urban.
Plots showing the relationship between the percentage of urban in a 500 m radius buffer and a) the abundance and b) the evenness of sphecids. Only significant results were presented (P < 0.05). Plots include expected value (black line), and 95% confidence interval (gray shading).
Fig 4.
Effects of landscape scale variables: Habitat area and contiguity index.
Plots showing the effects of the interaction of habitat area and habitat Contiguity index on a) the abundance and b) the evenness of sphecids, and c) the overall effect of habitat Contiguity index on the evenness of tachinids. Only significant results were presented (P < 0.05). Plots include expected value (black line), and 95% confidence interval (gray shading).
Fig 5.
Effect of the sub-regional scale variable.
Plots showing relationship between the distance from the city center and a) the species richness and b) the abundance of sphecids. Only significant results were presented (P < 0.05). Plots include expected value (black line), and 95% confidence interval (gray shading).