Rewilding: Pitfalls and Opportunities for Moths and Butterflies

Thomas Merckx

Abstract Small organisms provide the bulk of biodiversity. Here, we look at rewilding from their perspective. As an umbrella group for other terrestrial invertebrates, we focus on the diverse group of Lepidoptera. More specifically, we set out to explore their response to farmland abandonment. So far, studies have warned against farmland abandonment, which is for instance listed as one of the key threats to European butterfly diversity. Here, partly based on a case study within the Peneda mountain range, we argue (i) that the majority of Lepidoptera is to a greater or lesser extent forest-dependent, (ii) that effects on species composition should be considered at regional rather than smaller scales, and (iii) that habitat resource heterogeneity at multiple spatial scales is key. As such, we believe that rewilding does offer opportunities to Lepidoptera. However, we recommend rewilding not to be equalled to a hands-off approach, but rather to a goal-driven conservation management approach. It should monitor, and where necessary intervene to provide habitat heterogeneity at multiple spatial scales, in order to cater for the whole gradient of sedentary to mobile species. Given that sufficient levels of habitat heterogeneity are maintained, Lepidoptera are one of probably many taxa that are likely to benefit from rewilding processes on European marginal farmland. The resulting improved species composition will help achieve European species conservation targets. It may also lead to more viable populations of moths, butterflies and other invertebrates, which will foster more resilient food-webs and increased ecosystem functioning.

Keywords Farmland abandonment Habitat resource heterogeneity Spatial scale

Controlled Rewilding Lepidoptera

Rewilding Small-Sized Biodiversity Too

So far, the debate on rewilding opportunities for biodiversity has been mainly centred upon popular and hence large-sized taxa, such as large mammals and birds (see Chaps. 1, 4, 5, and 8). As home range extent is typically mirrored by organismal size, the relatively high mobility and large spatial footprint of large-sized taxa are mainly situated at the extreme end of a whole gradient. The bulk of biodiversity is smaller, less mobile, and hence operates at smaller spatial scales. Because of the considerable dimension of the amount of European agricultural land that is already being abandoned, and that is set to be abandoned over the next couple of decades (see Chap. 1), it is obvious why the rewilding concept provides a most welcome opportunity for wide-ranging and cursorial species, like wolves for example, whose ecology has simply not been compatible with the typically small nature reserves and the intensified countryside of Western Europe. However, for rewilding to be adopted as a credible land-use option and conservation strategy, it will need to provide more than only a handful of iconic large animals. The successful uptake of the rewilding approach may depend upon three main points: (i) rewilding will need to make (socio-)economic sense (see Chap. 10), (ii) ample supply of ecosystem services will need to be guaranteed (see Chap. 3), and last but not least, (iii) rewilding will need to make sense from a biodiversity conservation viewpoint too. As such, it needs to cater for all kinds of biodiversity, i.e. for rare, range-restricted and ubiquitous species, for generalists and specialists, for currently threatened and leastconcern species, for species operating at all kinds of spatial scales. With regard to this latter point, we here look at rewilding from the perspective of smaller-sized taxa. Although these taxa provide the bulk of biodiversity and ecosystem functioning, they are severely under-represented in conservation research (Clark and May 2002; Cardoso et al. 2011; Pereira et al. 2012). As an (incomplete) umbrella group for other terrestrial invertebrates (Thomas 2005), we focus on the ecologically diverse group of Lepidoptera.

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