Assessing the effect of the time since transition to organic farming on plants and butterflies

Abstract

1.Environmental changes may not always result in rapid changes in species distributions, abundances or diversity. In order to estimate the effects of, for example, land-use changes caused by agri-environment schemes (AES) on biodiversity and ecosystem services, information on the time-lag between the application of the scheme and the responses of organisms is essential.2.We examined the effects of time since transition (TST) to organic farming on plant species richness and butterfly species richness and abundance. Surveys were conducted in cereal fields and adjacent field margins on 60 farms, 20 conventional and 40 organic, in two regions in Sweden. The organic farms were transferred from conventional management between 1 and 25 years before the survey took place. The farms were selected along a gradient of landscape complexity, indicated by the proportion of arable land, so that farms with similar TST were represented in all landscape types. Organism responses were assessed using model averaging.3.Plant and butterfly species richness was c.20% higher on organic farms and butterfly abundance was about 60% higher, compared with conventional farms. Time since transition affected butterfly abundance gradually over the 25-year period, resulting in a 100% increase. In contrast, no TST effect on plant or butterfly species richness was found, indicating that the main effect took place immediately after the transition to organic farming.4.Increasing landscape complexity had a positive effect on butterfly species richness, but not on butterfly abundance or plant species richness. There was no indication that the speed of response to organic farming was affected by landscape complexity.5.Synthesis and applications. The effect of organic farming on diversity was rapid for plant and butterfly species richness, whereas butterfly abundance increased gradually with time since transition. If time-lags in responses to AESs turn out to be common, long-term effects would need to be included in management recommendations and policy to capture the full potential of such schemes.

Biodiversity conservation in agriculture requires a multi-scale approach

“…In addition to our primary search, we also reviewed the reference sections of several recent reviews and meta-analyses [10,26,29] and we also encountered and obtained data from two studies [30,31] via data requests for other studies. In total, we reviewed 822 published studies.…”

Functional identity and diversity of animals predict ecosystem functioning better than species-based indices

“…R. Soc. B 282: 20142620 (see [29] for design of the study). Earthworm communities were estimated from four soil samples (30 Â 30 Â 30 cm) per field, taken at least 20 m from the field edges and with a 20 m distance between each sample.…”

Generalist-specialist continuum and life history traits of Central European butterflies (Lepidoptera) - are we missing a part of the picture?

“…Specialists, in contrast, may be pre-adapted to habitat fragmentation (e.g., selection against mobile individuals, Komonen et al, 2004) (Habel & Schmitt, 2012;Habel et al, 2013). Consequently, specialists can be conserved by targeting their habitat patches, whereas conserving generalists may require land use adjustments over large scales (Rundlof & Smith, 2006;Jonason et al, 2011). As shown by Dapporto & Dennis (2013) for British butterflies, the currently most endangered species are "mid generalists", with intermediate positions on the generalist-specialist continuum, with too little dispersal ability for colonizing distant habitats and too high minimum area requirements to be able to survive in remnant habitat patches.…”