Monitoring arthropods under the scope of LIFE-Snails project – Baseline Data

The database we present is part of the LIFE SNAILS project (Support and Naturalization in Areas of Importance for Land Snails), which has the main aim of protect three species of terrestrial molluscs, two snails (Oxychilus agostinhoi and Leptaxis minor) and a semislug (Plutonia angulosa), which are endemic of Santa Maria Island, and whose populations are at high risk. In this study, we established a comprehensive database derived from a long-term arthropod monitoring campaign utilizing SLAM (Sea, Land, Air, Malaise) traps. While molluscs were not the focus, our findings present a credible proxy for assessing the overall habitat quality for endemic invertebrates, using arthropods as principal indicators.

Santa Maria is a small island (area: 97.2 km²; elevation: 590 m a.s.l.) of volcanic origin, belongs to oriental group of Azores archipelago (36°58′24″N 25°05′40″W). The sampling area consist on mixed-forests of endemic, native and exotic plant species. The main native and endemic species include, Morella faya, Erica azorica, Picconia azorica, Vaccinium cylindraceum or Laurus azorica. The exotic species include Pittosporum undulatum, Hedychium gardnerianum and also forestry plantations of Cryptomeria japonica. The climate is temperate oceanic, with regular and abundant rainfall, high levels of relative humidity and persistent winds, mainly during the winter and autumn seasons

Passive flight interception SLAM traps (Sea, Land and Air Malaise trap) were used to sample 11 sites located on mixed-forests of Santa Maria Island. This trap consists in a structure of 110x110x110 cm, where the trapped arthropods crawl up the mesh and then fall inside the sampling recipient (Borges et al. 2017). Each one is filled with propylene glycol (pure 1,2-PROPANODIOL) to kill the captured arthropods and conserve the sample between collections. Although this protocol was developed to sample flying arthropods, by working as an extension of the tree, non-flying species such as spiders can also crawl into the trap (Borges et al. 2017), enhancing the range of groups that can be sampled by this technique. Because of this, previous studies have used these traps to analyse diversity and abundance changes in the arthropod communities in Azores pristine forest sites (Matthews et al. 2019; Borges et al. 2020). The traps were installed during 30 consecutive days in three periods between September and December 2022, period after which samples were collected. Information of vegetation composition (dominant plant species in surrounding area) and elevation were recorded

Secretaria Regional do Ambiente e Alterações Climáticas, Project LIFE SNAILS (LIFE20 NAT/PT/001377