Managing hedgerows for biodiversity: Disentangling the effects of trimming, structure and connectivity on the use of linear features by bats

Hedgerows are key semi-natural elements in European agricultural
landscapes supporting diverse wildlife, including bats, that depend on
these linear elements for foraging and commuting. Despite replanting
initiatives, many hedgerows remain degraded due to intensive management
practices such as over-trimming. To develop effective and generalisable
conservation guidelines, more research is needed to understand how both
management practices and intrinsic hedgerow characteristics influence bat
species with different foraging strategies. We conducted passive acoustic
monitoring across 448 hedgerows to assess the influence of six
characteristics on bat activity: trimming method, height, width, foliage
density, connectivity, and woody plant diversity. We examined responses
for two species associated with hedgerow landscapes (Barbastella
barbastellus, Rhinolophus ferrumequinum), and three echolocation guilds:
short-, mid-, and long-range echolocators (SRE, MRE, LRE), corresponding
to clutter, edge, and open space foragers, respectively. Pollarding
consistently increased bat activity, especially for tree-dwelling species,
likely by maintaining mature trees with larger crowns and diversified
microhabitats. Coppicing generally reduced activity for SRE, B.
barbastellus, and R. ferrumequinum, while increasing LRE activity. Taller,
tree-filled hedgerows generally supported higher bat activity, whereas
width and foliage density had more limited effects. Finally, uninterrupted
hedgerow segments enhanced SRE and MRE activity, highlighting the
importance of local habitat continuity in creating effective corridors for
bat movement. Woody plant diversity was also positively associated with
SRE activity. These results were mostly consistent across simplified open
croplands and structurally complex bocage landscapes. Synthesis and
Applications: Our findings underscore the value of targeted hedgerow
management in promoting on-farm bat activity, and support the integration
of simple hedgerow quality assessment protocols into agri-environment
schemes. Consistent with previous research, we confirm the importance of
tall, tree-filled hedgerows and emphasize the need to preserve mature
trees. We also provide novel insights: hedgerow continuity and
low-intensity trimming methods can further improve habitat suitability,
particularly for tree-dwelling bats. Our management recommendations align
with evidence from other taxonomic groups, including birds and
invertebrates, and can contribute to broader biodiversity conservation
strategies.