Thinning does not reduce numbers of fruit-feeding nymphalid butterflies but may adversely affect regional endemics, in the Bossematié Forest Reserve, southeastern Cote d'Ivoire

Published source details Fermon H., Waltert M., Larsen T.B., Dall'Asta U. & Muehlenberg M. (2000) Effects of forest management on diversity and abundance of fruit-feeding nymphalid butterflies in south-eastern Cote d'Ivoire. Journal of Insect Conservation, 4, 173-189
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Summary

The Bossematié Forest Reserve in southeastern Côte d’Ivoire has been managed for the dual purposes of forestry and conservation since 1992. Two hundred and fifty two butterfly species have been recorded from the forest. This study monitored the effects of two different forest management strategies – thinning and afforestation - on the diversity and abundance of fruit-feeding Nymphalid butterflies.

Butterflies were monitored in three areas of the forest reserve – a 30 ha control compartment, a 30 ha compartment managed with ‘liberation thinning’ three years previously and a 15 ha compartment planted with three native tree species Terminalia ivorensis, T. superba and Triplochiton scleroxylon, five years previously (trees planted 6-9 m apart, grown to 10-12 m high). ‘Liberation thinning’ favours crop trees by cutting lianas and climbers, and killing (not felling) non-commercial tree species.

Fruit-feeding butterflies were monitored using 68 banana-baited traps set 1 m high in the understorey for six consecutive days at the end of the dry season between 21 January and 5 March 1996. Traps were placed 100 m apart, with 28 in the control and thinned areas, and 12 in the plantation compartment. They were checked every 24 hours.

In total, 97 butterfly species were recorded, all belonging to the family Nymphalidae (fruit feeders). All but four were tropical forest butterflies, with two savannah species and two ubiquitous species.

The average number of species was significantly higher in the control and thinned compartments (71 and 76 species respectively), than the plantation compartment (52 species).

Overall butterfly abundance did not differ between management types. Four butterfly genera were more abundant in the control compartment than in the plantation: the foresters Euphaedra, the nymphs Euriphene, the evening browns Gnophodes and Bebearia. One genus Charaxes was more abundant in the plantation compartment.

Five species were caught less frequently in the thinned compartment than the control compartment. Of these, four (Bicyclus abnormis, B. zinebi, Euphaedra crockeri and E. phaetusa) had restricted geographic ranges within Upper Guinea or West Africa. In contrast seven species caught more frequently in the thinned compartment were all widely distributed from western West Africa to Central or East Africa. This suggests that liberation thinning adversely affects specialised species with limited ranges.

Note: If using or referring to this published study, please read and quote the original paper, the abstract of which can be viewed at: http://www.springerlink.com/content/1366-638X