دانلود رایگان مقاله بازتاب شیب استرس های محیطی اجتماعات میکرو شبپره

Abstract

Isolated conservation areas embedded in a hemerobic landscape matrix run the risk of losing their functionality through stress impacts from their surroundings. We studied insects in one of the last remaining coastal forest reserves in northern Italy, viz. the Pineta san Vitale near Ravenna, to assess whether local assemblages are shaped by gradients of external environmental stressors. Specifically, we asked whether proximity to the nearest sources of aerially transported pollutants and extent of soil salinity affect communities. We used nocturnal micro-moths as target group since their usually high degree of host-plant specificity and often small body size lead us to expect these insects to reveal community differentiation at very small spatial scales within the reserve. We sampled 6085 moths representing 157 species at 16 light-trap sites during the vegetation period in 2013. We then assembled a matrix of 37 traits relating to larval niche, body size, phenology, migration behavior and habitat preferences from literature sources. With these data we established that species composition and overall functional diversity of local micro-moth assemblages was strongly influenced by the distance to pollution sources, and less so by soil salinity. In contrast, species richness and species diversity were not effective in depicting influences of these two environmental gradients. Our results show that micro-moth communities respond sensitively to environmental conditions on small spatial scales, yet not all community attributes are equally suitable to uncover such relationships. Species composition and functional diversity emerged as far more informative than measures of local species diversity

Conclusions

Even though an analysis of Mediterranean micro-moth communities met challenges in terms of species identifi- cations and the assembly of a functional trait matrix, our study revealed that these organisms are highly suitable to unravel environmentally induced changes in species composition and functional diversity. We attribute this to the high host plant specificity and strong habitat fidelity shown by many species of micro-moths. For the conservation status of PSV we conclude that active management of habitat quality should be adopted immediately to counter-act adverse effects imposed by environmental pollutants from outside the nature reserve. Such effects are already visible in terms of vegetation structure (Uhl & Wölfling 2015) and, as shown above, have repercussions on organisms at higher trophic levels. For example, local measures to reduce soil salinization or assisted regeneration of degraded vegetation units would likely contribute to restoring herbivore insect communities (Summerville et al., 2005) whose biodiversity is currently eroding under the negative influences that are swamping the reserve PSV.