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Table 10 Summary of the main effects highlighted in the narrative syntheses

From: Can linear transportation infrastructure verges constitute a habitat and/or a corridor for insects in temperate landscapes? A systematic review

Specific question Group Main effects on insect biodiversity Type of evidence Susceptibility to biasb
Q1 habitat/management practices A: vegetation restoration + to NS 6 control-impact studies 6 medium
B: artificialization of the LTI − to NS 4 control-impact studies, 1 BACI study 1 low, 4 medium
C: mowing and grazing Difficult to synthesize (inconsistencies) 5 control-impact studies, 1 BACI study 1 low, 5 medium
Q2 habitat in LTI verges vs. at proximity D: Coleoptera in terrestrial LTI verges in comparison with other habitats Difficult to synthesize (inconsistencies) 10 control-impact studies 6 low, 4 medium
E: pollinators in terrestrial LTI verges in comparison with other habitats NS to + 8 control-impact studies 4 low, 4 medium
F: “unwanted species” in road verges in comparison with other habitats NS to + 7 control-impact studies 2 low, 5 medium
G: other groupsa in terrestrial LTI verges in comparison with other habitats NS to + 10 control-impact studies 6 low, 4 medium
H: all species in aquatic LTI verges in comparison with other habitats Not possible to conclude (too few and inconsistent studies) 3 control-impact studies 1 low, 2 medium
Q3 dispersal/management practices No article   
Q4 dispersal in LTI verges vs. at proximity Not possible to conclude (too few and inconsistent studies) 2 control-impact studies 2 medium
Q5 habitat/surrounding landscape I: urbanization in the surrounding landscape − to NS 7 control-impact studies 3 low, 4 medium
J: agriculture in the surrounding landscape − to NS 5 control-impact studies 1 low, 4 medium
K: natural or protected areas in the surrounding landscape NS to + 4 control-impact studies 1 low, 3 medium
L: forested areas in the surrounding landscape NS to + 3 control-impact studies 2 low, 1 medium
Q6 dispersal/surrounding landscape No article   
  1. + positive effect, negative effect, NS statistically non-significant effect, NS to + effects mainly statistically non-significant but sometimes positive, + to NS effects mainly positive but sometimes statistically non-significant
  2. aInsects different from Coleoptera, pollinators and “unwanted species”
  3. bMedium: study with medium level of susceptibility to bias, low: study with low level of susceptibility to bias