Abundance and diversity of moths in woodland habitats.
The abundance and diversity of moths and their larvae are compared in various
woodland habitats within Bernwood Forest in lowland England to assess the
impact of large-scale planting of introduced conifers and of conservation
measures including coppicing and ride-side management.
Light trap catches of moths in conifer plantations and in a recently coppiced
site contained significantly fewer individuals and fewer species over the year
compared with sites in adjacent overgrown coppice, but species diversity,
measured by Fisher's index 0<. , was higher because cat ches in the latter were
dominated by some very abundant species.
Only 14 of the 431 species of macro-moths recorded from Bernwood Forest
have larvae which feed on conifers but 138 species were found breeding on
native weed species in the conifer plantations. Densities of larvae on
individual native shrubs in conifer plantations were not significantly different
from those in broadleaved stands. Mark and recapture of adult moths
demonstrated considerable movement between habitats.
More moths of more species were caught in rides than in adj acent woodland
stands using Robinson traps. Heath traps in rides frequently did not catch
more species or more moths than within woodland stands. Catches in Heath
traps were generally largest in overgrown coppice. Catches at all sites were
related to the abundance of larval host-plants but were also influenced by the
distance over which the trap was visible and the amount of canopy shade.
Three methods of cornpensat ing for differences in shade between trap-sites
Heath traps at ride intersects captured on average 55% of the species at a
Robinson trap per night; in woodland stands catches averaged 68% of the
At least thirteen nationally rare species have disappeared from Bernwood
since timber clearance prior to conifer planting.
The implications for biological survey work and for nature conservation are