Butterfly distribution along altitudinal gradients: temporal changes over a short time period

Abstract

Mountain ecosystems are particularly sensitive to changes in climate and land cover, but at the same time, they can offer important refuges for species on the opposite of the more altered lowlands. To explore the potential role of mountain ecosystems in butterfly conservation and to assess the vulnerability of the alpine species, we analyzed the short-term changes (2006–2008 vs. 2012–2013) of butterflies’ distribution along altitudinal gradients in the NW Italian Alps. We sampled butterfly communities once a month (62 sampling stations, 3 seasonal replicates per year, from June to August) by semi-quantitative sampling techniques. The monitored gradient ranges from the montane to the alpine belt (600–2700 m a.s.l.) within three protected areas: Gran Paradiso National Park (LTER, Sitecode: LTER_EU_IT_109), Orsiera Rocciavrè Natural Park and Veglia Devero Natural Park. We investigated butterflies’ temporal changes in accordance with a hierarchical approach to assess potential relationships between species and community level. As a first step, we characterized each species in terms of habitat requirements, elevational range and temperature preferences and we compared plot occupancy and altitudinal range changes between time periods (2006–2008 vs. 2012–2013). Secondly, we focused on community level, analyzing species richness and community composition temporal changes. The species level analysis highlighted a general increase in mean occupancy level and significant changes at both altitudinal boundaries. Looking at the ecological groups, we observed an increase of generalist and highly mobile species at the expense of the specialist and less mobile ones. For the community level, we noticed a significant increase in species richness, in the community temperature index and a tendency towards homogenization within communities. Besides the short time period considered, butterflies species distribution and communities changed considerably. In light of these results, it is fundamental to continue monitoring activities to understand if we are facing transient changes or first signals of an imminent trend.

Effects of Temperature Rise on Multi-Taxa Distributions in Mountain Ecosystems

“…These results indicate that butterflies can respond quickly to warming, determining new species assemblages, in particular at high altitudes and that the vegetation structure has the potential to buffer this response. Similar results were found analyzing observed temporal changes in butterfly distribution and community composition [106,107], also during a short time frame [108] and in the same mountain ranges considered here [53].…”

Climate warming drives divergence of montane butterfly communities in Southern Italy

“…At lower altitudes, a decline of high-elevation species and a general increase in semi-natural habitats of thermophilous ones have been observed, suggesting a causal effect of climate warming on the composition of butterfly communities (Zografou et al 2014). Short-term changes are less pronounced and cannot be univocally attributed to the recent increases in temperature, as individual species population dynamics can conceal such low level of changes (Zografou et al 2014;Cerrato et al 2019). Studies concerning individual species confirm the results obtained for the entire species assemblages, showing an elevational upward shift of about 200 m of their range (Wilson et al 2005;Scalercio et al 2014).…”

“…During this period, four sampling sessions were carried out, separated by no less than 14, and no more than 20 days during optimal weather conditions for butterfly activity (sunny days, no or low wind speed). In previous studies on the effects of climate change on Mediterranean butterfly communities along altitudinal gradients, not enough details were provided on changes occurring in the highest altitude communities as sites were grouped in wide altitudinal band (Wilson et al 2005(Wilson et al , 2007Cerrato et al 2019). In this study, we focused our attention only on the highest sites sampled by Balletto and collaborators, grouping sites into altitudinal band: (i) low altitudinal band (1470-1575m a.s.l.)…”

“…An increasing number of papers are devoted to describing the effects of climate change on the latitudinal and altitudinal range of butterflies. Studies across southern Europe (Wilson et al 2005(Wilson et al , 2007Zografou et al 2014;Cerrato et al 2019), and other geographic areas (Pounds et al 1999;Shoo et al 2006;Despland et al 2012;Molina-Martínez et al 2013;Dewan et al 2019), tend to lump high-elevation sites together into one "high" altitudinal band which fails to consider potential differences in species' responses to climate change within montane habitats. Specifically, mountaintop alpine environments often differ considerably from those just at or below treeline, although they are all typically considered "high elevation" habitats.…”

Editorial

“…For the terrestrial environment, papers in this Special Issue investigate the effects of climate variability and habitat use on the biological and biogeochemical components of ecosystems from the sea-level coasts to the peaks of the Alps in a variety of habitat types, such as forests, grasslands and dunes. Amongst the "sentinels" of environmental changes, the readers will find the high-elevation plants reported by Petriccione and Bricca (2019), which varied significantly in the species coverage, and the butterflies whose variations in species distribution and community composition was investigated by Cerrato et al (2019). Carbon and nitrogen cycles are influenced by climatic drivers, as well as by the atmospheric inputs and the study of these elements in the soil and soil solution provides important data on the ecosystem functioning, as outlined by Freppaz et al (2019) in the alpine tundra and by Balestrini et al (2019) in a montane forest.…”