-180

180

90

-90

Kingdom

Animalia

Class

Arachnida

ADMINISTRATIVE_POINT_OF_CONTACT

Terceira Island (area: 400.6 km²; elevation: 1,021.14 m) is one of the nine islands from the Azores archipelago, located in the North Atlantic, roughly at 38°43′49″N 27°19′10″W. The climate in the Azores is temperate oceanic, with regular and abundant rainfall, with high levels of relative humidity and persistent winds, mainly during the winter and autumn seasons. Terceira Island is known for the presence of some very important pristine areas at high elevation (Gaspar et al. 2011). However, few natural areas still remain at lower elevations, notably in Praia da Vitória’s council.

At all plots we applied the optimised and standardised COBRA (Conservation Oriented Biodiversity Rapid Assessment) sampling protocol for temperate forests (Cardoso 2009). Different variants of the COBRA protocol for spiders have already been applied in oceanic islands (Emerson et al. 2017) and tropical forests (Malumbres-Olarte et al. 2016, Malumbres-Olarte et al. 2017). Although originally developed and optimised for mainland habitats, COBRA has been recently proposed to be the standard protocol for inventorying and monitoring island forest ecosystems (Borges et al. 2018).

The forest COBRA protocol consisted of: four night aerial samples (1 hour / sample), two day sweeping samples and two night sweeping samples (1 hour / sample), two day beating samples and two night beating samples (1 hour / sample) and 12 pitfall samples (4 traps / sample). In addition, we collected the following samples to cover beetle diversity (Borges et al. 2018): two diurnal active aerial searching under bark, lichens and bryophytes (ABS) (1 hour / sample) and two diurnal active aerial searching in decaying trunks, dead wood on the ground and under stones (GWS) (1 hour / sample). The protocol for dry open areas was composed of: four night ground samples (1 hour / sample) and four day sweeping samples and four night sweeping samples (1 hour / sample). Sampling occurred in August 2016 (forest habitat plots of Madeira) and April 2017 (dry habitat plots of Madeira and Porto Santo).

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 contains 562 records (eventID). One extension data table also exists with 3281 occurrences. The extension supplies extra information about the core record.

We established twenty-two 50 m x 50 m plots grouped according to habitat and between-plot distances. Twelve plots were located in areas covered with laurisilva, and grouped in two sets of six. Within each set, plots were placed at increasing distances from a first, reference plot: 0.1, 1, 5, 10 and 20 km (Fig. 1). The remaining 10 plots were located in areas of open dry habitat, five on Madeira island and five on Porto Santo, also at increasing distances (0.1, 1, 5 and 10 km). This design allowed to test distance decay patterns on beta diversity in a log scale for the MACDIV project.

We applied two versions of the optimised and standardised COBRA protocol (Conservation Oriented Biodiversity Rapid Assessment) (Cardoso 2009), the one for temperate forests and the one for open habitats, to forest and dry habitat plots, respectively. The COBRA protocols have been proposed as part of standard inventorying and monitoring programs on island and continental ecosystems, and have already been used for a number of studies on spiders and beetles (Cardoso 2009, Borges et al. 2018, Malumbres-Olarte et al. 2017, Malumbres-Olarte et al. 2018). The forest COBRA protocol consisted of: four night aerial samples (1 hour / sample), two day sweeping samples and two night sweeping samples (1 hour / sample), two day beating samples and two night beating samples (1 hour / sample) and 12 pitfall samples (4 traps / sample). In addition, we collected the following samples to cover beetle diversity (Borges et al. 2018): two diurnal active aerial searching under bark, lichens and bryophytes (ABS) (1 hour / sample) and two diurnal active aerial searching in decaying trunks, dead wood on the ground and under stones (GWS) (1 hour / sample). The protocol for dry open areas was composed of: four night ground samples (1 hour / sample) and four day sweeping samples and four night sweeping samples (1 hour / sample). Sampling occurred in August 2016 (forest habitat plots of Madeira) and April 2017 (dry habitat plots of Madeira and Porto Santo).