Long-term monitoring of Azorean forest arthropods: the BALA Project (1997-2022)

Abstract

The BALA dataset originates from various projects that employed a consistent sampling protocol to collect arthropods in the Azorean archipelago. Specifically, the Biodiversity of Arthropods from the Laurisilva of the Azores (BALA) project was initiated to comprehensively survey the invertebrate fauna of the Azores, focusing particularly on endemic arthropod species. The core sampling, conducted in three consecutive phases, targeted the identical 30 sites in a repetitive manner. Nevertheless, during the initial sampling round known as BALA1, spanning from 1997 to 2004, a collaborative endeavor from multiple projects led to the surveying of a total of 100 sites across 18 forest fragments in seven islands. During the subsequent rounds, spanning from 2010 to 2012 (BALA2) and 2021 to 2022 (BALA), only the 30 core sites, out of the original 100 sites, located within 15 fragments were revisited and resampled. Altogether, the collection amasses a total of 266,675 specimens of 543 invertebrate morphospecies (123,446 individuals and 404 species in the core dataset), of which 354 are identified at the species level. Of these species 77 (105,919 individuals) are endemic to the Azores, 97 (97,562 individuals) are native but not endemic, and 146 (32,267 individuals) are exotics.