Population dynamics and the importance of habitat management for conservation of the butterfly Lopinga achine

Abstract

Summary1. Like many butterflies, the woodland brown Lopinga achine has disappeared from many locations in western Europe due to habitat loss. The population dynamics and the effects of tree and bush cover on population size were studied experimentally south of Linköping, Sweden. 2. Most populations in the study area were small (< 500 individuals) and fluctuated synchronously between years. Long-term population dynamics and occurrence were closely correlated with tree and bush cover. Populations occurred only at sites with ≥ 60% canopy cover, but population density decreased sharply where cover exceeded 90%. Survival from egg to adult was highest at the edges of glades (2·3 adults per female) and lowest in the deepest shade (0·7 adults) or open sun (0·6 adults). The annual rate of canopy closure at unmanaged sites decreased linearly with tree and bush cover, approximately 1% closure at 60% cover and 0·3% at 85% cover, making it possible to predict the impact of habitat changes for L. achine . 3. In 1992-95, vegetation was cleared experimentally to create new glade edges at six unmanaged sites where the risk of extinction was high because few glades remained. On average, population size at five of the managed sites increased by > 90%. The population at the sixth site, managed in 1995, decreased by 30%. 4. Cover of the host-plant Carex montana increased significantly at edges of new glades and decreased in closed unaffected woods. Successful restoration probably requires the presence of C. montana along edges of new glades from the onset of management because this plant was slow to colonize plots where it was initially absent. 5. Currently, 86% of the sites in southern Sweden occupied by L. achine are unmanaged. If this situation continues, the metapopulation in this study will probably collapse within 20-40 years. Recovery programmes for L. achine should emphasize metapopulation dynamics, host-plant cover and vegetation dynamics over time. As with many butterflies, successful conservation requires a blend of detailed autoecology and active site management to produce the required successional conditions.

Relative importance of habitat area, connectivity, management and local factors for vascular plants: spring ephemerals in boreal semi-natural grasslands

“…cross-validation correlation/AUC) for the six spring ephemeral plant species and their richness cvAUC/ROC, cross-validation area under the curve (AUC) of a receiver operating characteristic (Hybrid models including variables from all three groups of variables and hybrid models excluding radiation and connectivity Species richness semi-natural grasslands may provide synergetic conservation beneWts and improve the occurrences of both animals and plants (see alsoBergman 2001;Schultz and Crone 2005).…”

Fox-hunting in England and Wales: its contribution to the management of woodland and other habitats

“…The species has shown a slight re-expansion in range since 1982 but it remains a BAP Species of Conservation Concern. It is agreed that the loss of coppicing and encroachment of the canopy has had a detrimental effect on both butterfly abundance and diversity (Pollard 1977;McKay 1991;Greatorex-Davies et al 1992;Sparks et al 1994;Warren 1993Warren , 1995Bergman 2001). This is also true for other invertebrate groups.…”

Relative importance of host plant patch geometry and habitat quality on the patterns of occupancy, extinction and density of the monophagous butterfly Iolana iolas

“…Since about one third of individuals usually fly at the flight peak in butterflies (Bergman 2001;Välimäki and Itämies 2003), we estimated total population sizes by multiplying the population size estimate at the flight peak by 3. There were a variable number of small patches in which no individual was seen during transect counts but where there was evidence of I. iolas presence in that year based on egg occurrence.…”