Diversity and composition of tropical butterflies along an Afromontane agricultural gradient in the Jimma Highlands, Ethiopia

Abstract

Afromontane landscapes are typically characterized by a mosaic of smallholder farms and the biodiversity impacts of these practices will vary in accordance to local management and landscape context. Here, we assess how tropical butterfly diversity is maintained across an agricultural landscape in the Jimma Highlands of Ethiopia. We used transect surveys to sample understory butterfly communities within degraded natural forest, semi‐managed coffee forest (SMCF), exotic timber plantations, open woodland, croplands and pasture. Surveys were conducted in 29 one‐hectare plots and repeated five times between January and June 2013. We found that natural forest supports higher butterfly diversity than all agricultural plots (measured with Hill's numbers). SMCF and timber plantations retain relatively high abundance and diversity, but these metrics drop off sharply in open woodland, cropland and pasture. SMCF and timber plantations share the majority of their species with natural forest and support an equivalent abundance of forest‐dependent species, with no increase in widespread species. There was some incongruence in the responses of families and sub‐families, notably that Lycaenidae are strongly associated with open woodland and pasture. Adult butterflies clearly utilize forested agricultural practices such as SMCF and timber plantations, but species diversity declines steeply with distance from natural forest suggesting that earlier life‐stages may depend on host plants and/or microclimatic conditions that are lost under agricultural management. From a management perspective, the protection of natural forest remains a priority for tropical butterfly conservation, but understanding functioning of the wider landscape mosaic is important as SMCF and timber plantations may act as habitat corridors that facilitate movement between forest fragments.

Butterfly Diversity and Abundance in the Middle Afromontane Area of Northwestern Ethiopia

“…Other workers have reported more taxa and less population than the present study [38,39]. Habitat differences are the plausible reasons.…”

Views from two mountains: exploring climate change impacts on traditional farming communities of Eastern Africa highlands through participatory scenarios

“…On the other hand, lower population density than in the Taita Hills provides higher chances for adaptive transformation and system resilience enhancement. Despite the positive effect of coffee presence in limiting the conversion of forest to annual-crop agriculture, intensification of coffee management under the coffee industry scenario could threaten forest dependent species biodiversity (Norfolk et al 2017b), including the genetic diversity of wild coffee (Hylander et al 2013). Moreover, in the coffee industry scenario farmers feared the increased dependence on food purchasing and on external market price fluctuations.…”

Land‐use change differentially affects endemic, forest and open‐land butterflies in Madagascar

“…These contrasting results can be explained by the different landscape settings of these studies. Landscape variables such as distance to forest or proportion of semi‐natural habitats are important to define the diversity of land‐use systems in the agricultural matrix (Barlow et al, 2007; Munyuli, 2013; Norfolk et al, 2017; Vasconcelos et al, 2015). In addition, butterflies vary in their ability to move across the matrix (Scriven et al, 2017).…”

“…Among insects, butterflies are a relatively well‐studied group, but data remain scarce for tropical butterflies even though they account for around 90% of all butterfly species (Bonebrake et al, 2010). Tropical forest conversion typically reduces butterfly diversity (Ghazoul, 2002; Norfolk et al, 2017; Sharma et al, 2020). However, not all tropical butterfly species are confined to the forest (categorised as ‘forest butterflies’; Koh et al, 2004), but many occur in human‐modified open or semi‐open areas such as grasslands, cropland, or secondary formations such as fallows (categorised as ‘open‐land butterflies’).…”

“…In such heterogeneous and highly fragmented landscapes, agroforestry is promoted as a profitable and yet biodiversity‐friendly land‐use option (Schroth et al, 2004). Structurally diverse agroforests can harbour forest butterfly species (Francesconi et al, 2013; Norfolk et al, 2017; Schmitt et al, 2020) as well as widespread (non‐endemic) butterfly species (Waltert et al, 2011). However, land‐use history affects the biodiversity value of agroforests depending on their establishment on fallow or forested land (Martin et al, 2020).…”