Abstract
Isolated fragments of semi-natural habitats are often embedded in a landscape matrix that is hostile to organisms of conservation concern. Such habitat islands are prone to changes in their biota over time. For insects, few studies on long-term trends in species richness within conservation areas are available, mainly due to the lack of historical data. We here use moths in the coastal pine wood reserve Pineta san Vitale (Ravenna, NE Italy) to assess how local fauna has changed over the last 85 years. This reserve has experienced massive changes in vegetation structure due to secondary succession. We compared historical collections (1933–1976: 107 species; and 1977–1996: 157 species) with our own samples (1997–2002: 174 species; and 2011+2012: 187 species). Over the last 85 years, the proportion of habitat generalists in relation to all recorded moth species increased from 20 to 33%. The fractions of woodland and open habitat species concomitantly decreased by 10 percentage points, respectively. Amongst woodland and habitat generalist species, gains outnumbered losses. In contrast, 18 species of open habitats and 10 reed species were lost over the decades. We attribute these changes to vegetation succession and to the isolation of the reserve. Generalist species are presumably better able to pass through anthropogenically exploited landscapes and colonise isolated habitat fragments than habitat specialists.
Highlights
Mediterranean coastal pine forests are vulnerable and rare ecosystems
In areas where anthropogenic influence has been severe over decades, long term studies are of great interest because they can mirror changes in an ecosystem best and shed light on the steady erosion of biodiversity (Habel et al 2016)
Historical records could be traced for 219 macro-moth species that were observed in PsV during the 20th century
Summary
Mediterranean coastal pine forests are vulnerable and rare ecosystems They provide habitat for many species, but have experienced massive contractions over centuries and are nowadays strongly at risk through anthropogenic land-use intensification (Gasparella et al 2017). Some species may persist for decades in conservation areas, but eventually get lost over time, be it due to ecosystem degradation or just attributable to stochasticity. This notion has led to the concept of an extinction debt and, only in the long term, can it be evaluated whether organisms are really safe in the reserves that have been set aside for their conservation (Carroll et al 2004, Halley et al 2016). In areas where anthropogenic influence has been severe over decades, long term studies are of great interest because they can mirror changes in an ecosystem best and shed light on the steady erosion of biodiversity (Habel et al 2016)
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