Long-term monitoring of Azorean forest spiders

Study Extent

A total of twenty 50m x 50m plots were sampled in two of the islands from the archipelago, 13 in Terceira and 7 in Pico. The areas where these plots were set constitute some of the most well-preserved wet forests in these islands, having small human disturbance (Borges et al, 2017). In Terceira the plots are dominated by endemic vegetation such as Juniperus brevifolia, Erica azorica, Laurus azorica and Ilex perado subsp. azorica (see Borges et al, 2017 for more details). In Pico, the plots at lower elevation (0-400 m a.s.l.) are dominated by Erica azorica and Morella faya, but with some presence of Pittosporum undulatum. At higher elevations (600-1000 m a.s.l.) the dominant vegetation is composed by Laurus Azorica, Juniperus brevifolia and Ilex perado zorica.

Sampling

Passive flight interception SLAM traps (Sea, Land and Air Malaise trap) were used to sample the plots in both islands, with one trap being setup at each plot, each one being 110 x 110 x 110 cm. In this type of trap 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, enabling also the preservation of DNA for future genetic analysis. 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 samples were collected every 3 months between September 2013 and December 2018 in Pico, and between June 2012 and January 2020 in Terceira. A monthly collection was also performed in Terra-Brava T18 on Terceira, which happened between January 2014 and June 2016.

Quality Control

All sorted speciments were identified by a taxonomical expert.

Method steps

1. The data has been published as a Darwin Core Archive (DwC-A), which is a standardised format for sharing biodiversity data as a set of one or more data tables. The core data table (events) contains 495 records and one data table extension also exists (occurrence), with 3025 records. The extension supplies extra information about the core record

Pico and Terceira islands in Azorean archipelago (Portugal)