Positive forestry: The effect of rubber tree plantations on fruit feeding butterfly assemblages in the Brazilian Atlantic forest

- We evaluated the role of rubber tree plantation on butterfly biodiversity in Brazil.
- Plantation harbored a diverse fauna but results depended on management regime.
- Management with undergrowth suppression led to less diverse butterfly assemblage.
- Low herbicide application groves contained more diverse butterfly communities.
- Strategies to promote understory growth should be encouraged by industry.

Agroforestry systems have increased in area in tropical regions in recent decades and many studies have sought to evaluate their impact on native biodiversity. Yet, few have assessed the impact of perennial plantations such as rubber-tree harvesting on native biodiversity. The goal of our study was to assess the effect of rubber tree plantations on fruit-feeding butterflies of the endangered Brazilian Atlantic Forest in Brazil. To do so, we sampled fruit- feeding butterfly species in a landscape mosaic composed of primary forest, rubber tree plantations under two management regimes (active production with intense management and undergrowth suppression and low management plantations with no undergrowth suppression), and forest fragments immersed in rubber tree plantation matrix. By trap-baiting butterflies for a year, we captured 5800 individuals of 85 butterfly species. Species richness was higher in unmanaged (no growth suppression) plantation and forest fragments (57-60 species) and lower in managed plantation (with growth suppression) (47) and primary forest (43). Ordination analysis suggests three main community groups formed by primary forest samples, a cluster combining unmanaged plantation and fragments, and managed plantation. There was substantial variation in butterfly abundance in the landscape, but our data suggest that several forest specialists species are able to occur along the mosaic on the landscape, and despite differences in management the entire landscape can contribute for a rich biota. Loss of understory vegetation led to simplified communities, with skewed dominance of a few species. By allowing understory development, a low impact management can provide adequate habitat for native butterflies. Yet, current rubber tree plantation technology does not normally use this method, opting to use the high management approach instead. We hypothesize that these minimally benign plantations may serve as conduits for butterflies in forest patches. Thus, we suggest that rubber tree plantations near Atlantic forest fragments should encourage understory development and establish a landscape mosaic, allowing forest fragments immersed in plantation matrix to be able to exchange individuals and colonize more complex plantation habitat. Intensive suppression of undergrowth should be avoided, except for trail maintenance, and isolation of fragments in this matrix should be kept to a minimum. If undergrowth suppression cannot be avoided, then establishment of stepping stones in plantation matrix should be encouraged to reduce isolation of fragments.