This manuscript is the first contribution of the project, "Matela – uma ilha de biodiversidade" ("Matela - an island of biodiversity"), that aims to restore the native vegetation within the Azorean Protected Area of the Terceira Island Nature Park known as the "Protected Area for the Management of Habitats or Species of Matela" (TER08), situated on Terceira Island, the Azores Archipelago, Portugal. This small fragment of native forest, positioned at a low-medium altitude (300-400 m a.s.l.), is facing some conservation impacts as a consequence of the spread of different invasive exotic plant species, mainly Pittosporum undulatum, Rubus ulmifolius and Hedychium gardnerianum. The database we present encompasses diverse taxonomic groups, including bryophytes, vascular plants, arthropods, birds and mammals. It is derived from intensive sampling campaigns conducted in 2022, but some data from a previous vascular plant survey in 2015 were also included. The objective of this study was to provide an updated inventory of bryophytes, vascular plants, arthropods, birds and mammals within this protected area. In this way we are providing the reference conditions necessary for the monitoring of the impacts of the current ongoing restoration efforts within the project "Matela - an island of biodiversity". Whenever feasible, the present inventory is juxtaposed with historical data from previous surveys conducted in Matela.

In the realm of bryophytes, our analysis revealed the presence of 75 taxa, comprising 44 mosses and 32 liverworts. Amongst these, 71 were indigenous, while three remained indeterminate and one, Campylopus introflexus, was identified as invasive. A comparison with previous historical data revealed a decrease in species richness, which was partially counterbalanced by the discovery of 23 new recorded species in the area.

Regarding vascular plants, we distinguished 54 species, comprising 28 indigenous and 26 introduced taxa. Almost 80% of the inventoried species (n = 43) were newly documented in Matela.

The study of arthropods encompassed a total of 103 taxa. Within the realm of soil arthropods, we documented eight indigenous and 25 introduced taxa, witnessing the disappearance of endemic species alongside a substantial increase in introduced ones between 2002 and 2022. Canopy arthropods, totalling 36 indigenous and 18 introduced taxa, exhibited few changes when compared with data from 2002. SLAM traps captured 24 indigenous and 15 introduced arthropod taxa and no historical data are available for comparison.

As for avian species, we noted 12 indigenous birds and one introduced species, confirming the presence of most of the historical recorded native species.

The mammalian census revealed eight introduced species, setting new precedents for Matela, alongside the identification of one endemic species: the Azorean endemic bat Nyctalus azoreum.