Biodiversity Data Journal : Data Paper (Biosciences)
PDF
Data Paper (Biosciences)
Vertical distribution of arthropod assemblages in native and exotic forests of Terceira Island (Azores, Portugal)
expand article infoSébastien Lhoumeau‡, Abrão Leite§, Laurine Parmentier‡, Clémence Massard|, Martha Vounatsi, Georgery Lucie#, Paulo A. V. Borges‡,¤,«
‡ University of the Azores, cE3c- Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group, CHANGE – Global Change and Sustainability Institute, School of Agricultural and Environmental Sciences, Rua Capitão João d'Ávila, Pico da Urze, 9700-042, Angra do Heroísmo, Azores, Portugal
§ Rua Fernando Pessoa, nº99 R/C DTO 2765-483, Estoril, Portugal
| Mestrado em Gestão e Conservação da Natureza, University of the Azores Rua Capitão João d'Ávila, Pico da Urze 9700-042, Angra do Heroísmo, Azores, Portugal
¶ Department of Ecology and Taxonomy, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
# UCLouvain - Unamur, Faculty of Biology, Louvain-La-Neuve, Belgium
¤ IUCN SSC Atlantic Islands Invertebrate Specialist Group, Angra do Heroísmo, Azores, Portugal
« IUCN SSC Monitoring Specialist Group, Angra do Heroísmo, Azores, Portugal
Corresponding author: Sébastien Lhoumeau (seb.lhoumeau@gmail.com)
Academic editor: António O. Soares
Received: 28 Mar 2025 | Accepted: 05 May 2025 | Published: 20 May 2025
© 2025 Sébastien Lhoumeau, Abrão Leite, Laurine Parmentier, Clémence Massard, Martha Vounatsi, Georgery Lucie, Paulo Borges
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Lhoumeau S, Leite A, Parmentier L, Massard C, Vounatsi M, Lucie G, Borges PAV (2025) Vertical distribution of arthropod assemblages in native and exotic forests of Terceira Island (Azores, Portugal). Biodiversity Data Journal 13: e154240. https://doi.org/10.3897/BDJ.13.e154240
 Open Access

Abstract

Background

In the summer of 2024, a study was conducted on Terceira Island in the Azores Archipelago, Portugal, aiming to characterise the vertical diversity and spatial distribution patterns of arthropods within native and exotic forest ecosystems. This study forms part of a broader research initiative designed to investigate how alterations in habitat structure influence the complexity and stability of arthropod food webs in Azorean forest habitats. By systematically sampling arthropods across multiple vertical strata —from forest floor to canopy the study aimed to generate detailed insights into the ecological dynamics governing biodiversity patterns and species interactions. Results from this monitoring will contribute significantly to understanding the ecological impacts of forest composition and management strategies, ultimately providing information for conservation planning and habitat restoration efforts aimed at preserving arthropod diversity and ecological resilience in island ecosystems.

New information

The current dataset comprises identified terrestrial arthropods collected using SLAM (Sea, Land and Air Malaise) traps and Pitfall traps across diverse forest strata. A total of 32,797 specimens were collected from the Arachnida, Diplopoda, Chilopoda and Insecta classes. A total of 18,372 (56%) were identified at the species or subspecies level, including 12,745 adults and 5,627 juveniles for taxa, such as Araneae and Hemiptera due to the availability of reliable identification methods. The resulting dataset encompasses 150 species and 11 subspecies, distributed across 21 orders, 81 families and 148 genera.

Hemiptera emerged as the most abundant identified order, with a total of 7,697 recorded specimens and Coleoptera stood as the most taxonomically diverse, encompassing 19 distinct families and 50 species and sub-species. The ten most abundant species comprise predominantly endemic and native non-endemic species, with two exotic species detected amongst them.

This comprehensive dataset serves as a significant augmentation of the existing baseline knowledge concerning the diversity of Azorean arthropods, thereby facilitating the formulation of future long-term ecological comparisons. It offers valuable insights into the vertical distribution of species abundance within both native and exotic forests of the Azores.

Keywords

occurrence, specimen, Arthropoda, Azores, forest stratification, SLAM trap, Pitfall trap, sampling event

Introduction

Forests represent amongst the most structurally complex ecosystems on Earth (Pan et al. 2013, Ehbrecht et al. 2021), characterised by distinct vertical strata that support a wide range of biodiversity (Oliveira and Scheffers 2019). The vertical stratification of forests plays a crucial role in shaping species distributions, ecological interactions and resource availability (Laurans et al. 2014, Thiel et al. 2021, Basham et al. 2023). The different forest layers — ranging from the forest floor to the canopy — offer distinct environmental conditions, including variations in temperature, humidity, light availability and plant composition (Chen et al. 1999, De Frenne et al. 2019). Consequently, many forest-dwelling organisms, including arthropods, exhibit strong vertical preferences and niche partitioning (Basset et al. 2003). However, despite the recognised importance of vertical stratification in forest ecology, studies on arthropod diversity across forest layers remain limited, especially in insular ecosystems (but see Costa et al. (2023)).

Arthropods are considered to be one of the most functionally diverse and ecologically significant animal groups. They play key roles in decomposition, pollination, herbivory, predation and soil aeration (Wong et al. 2019, Cardoso et al. 2020, Cardoso et al. 2024). Due to their sensitivity to habitat structure and environmental changes, arthropods are widely used as bioindicators of ecosystem health (Tsafack et al. 2023). Understanding their distribution across vertical forest layers can provide insights into species interactions, habitat specialisation and the effects of environmental disturbances on biodiversity. In island ecosystems, where species assemblages are often shaped by historical colonisation events, habitat fragmentation and the introducion of invasive species (Fernández-Palacios et al. 2021), investigating arthropod vertical stratification can be particularly valuable for conservation planning. Island ecosystems, such as those of the Azores (Portugal), exhibit unique biodiversity patterns, shaped by isolation, habitat heterogeneity and anthropogenic influences, making them valuable natural laboratories for ecological reserach and biodiversity management strategies (Mueller-Dombois 1992).

The Azorean forests, include both native and exotic forest types, each of which differs in terms of floristic composition, structural complexity and historical land use (Dias et al. 2004, Elias et al. 2016, Borges Silva et al. 2022). The native forests, which are dominated by endemic tree species, such as Laurus azorica, Ilex azorica and Juniperus brevifolia, represent remnants of the Pliocene/Pleistocene forests in Macaronesia (Kondraskov et al. 2015). These forests are distinguished by their notable levels of endemism and conservation importance, offering critical habitat for specialised arthropod species (Borges et al. 2022, Lhoumeau and Borges 2023). In contrast, exotic forests are characterised by the presence of the invasive species Pittosporum undulatum, along with other non-native vascular plants and are the result of deliberate afforestation for timber production and land management purposes (Dias et al. 2004, Borges Silva et al. 2017). As a consequence, they frequently exhibit a lack of structural and botanical diversity when compared to native forests, potentially influencing the composition and distribution of arthropod communities.

Given that many insular arthropods exhibit high levels of habitat specialisation and restricted dispersal abilities (Gillespie and Roderick 2002), their vertical distribution within forest strata could be influenced by both natural forest structure and anthropogenic modifications. Additionally, the replacement of native forests with exotic species may lead to changes in arthropod assemblages by altering microhabitat conditions, reducing resource availability and disrupting ecological interactions.

General description

Purpose: 

The present dataset encompasses terrestrial arthropods that have been collected using Pitfall traps and SLAM (Sea, Land, and Air Malaise) traps across a variety of forest strata. This dataset is the material result of sampling events that have been conducted within the framework of a project that aims to evaluate the impact of habitat structure change on arthropod food web complexity in Azorean forests. In particular, the study seeks to assess how changes in arthropod biodiversity are influenced by the structural complexity of forests.

Project description

Title: 

The impact of habitat structure change on arthropod food web complexity in Azorean forests.

Personnel: 

Paulo A. V. Borges, Sébastien Lhoumeau, Laurine Parmentier, Abrão Leite, Clémence Massard, Martha Vounatsi, Georgery Lucie

The project was conceived and is being led by Sébastien Lhoumeau and Paulo A.V. Borges.

Fieldwork (site selection and experimental setting): Sébastien Lhoumeau and Paulo A.V. Borges.

Fieldwork (authorisation): Licença Nº 23/2024/DRAAC; ADENDA CCIR-RAA/2024/7.

Fieldwork: Sébastien Lhoumeau, Clémence Massard, Martha Vounatsi, Georgery Lucie and Paulo A.V. Borges.

Parataxonomists (Laboratory): Sébastien Lhoumeau, Laurine Parmentier, Abrão Leite, Clémence Massard, Martha Vounatsi, Georgery Lucie.

Taxonomists: Paulo A. V. Borges.

Arthropod Curation: Voucher specimen management was mainly undertaken by Sébastien Lhoumeau, Laurine Parmentier and Abrão Leite.

Darwin Core Databases: Sébastien Lhoumeau and Paulo A.V. Borges.

Study area description: 

The Azores constitute an isolated archipelago located in the northern part of the mid-Atlantic Ocean, approximately 1,400 kilometres west of mainland Portugal. Comprising nine volcanic islands — namely Corvo, Flores, Faial, Pico, São Jorge, Graciosa, Terceira, São Miguel and Santa Maria — the Archipelago extends across roughly 500 km in a west-northwest to east-southeast orientation. Santa Maria, with its age around 6 to 8 million years, is the most ancient island within the archipelago. In contrast, Pico, the youngest island, has an estimated age of around 0.19 million years (Florencio et al. 2021). The islands emerged through volcanic activity along the Mid-Atlantic Ridge, a tectonic boundary zone, characterised by ongoing seismic and geothermal phenomena and most of the islands are relatively young (Florencio et al. 2021). This volcanic origin has endowed the Azorean Islands with rugged terrains, diverse habitats and unique ecological communities, which together contribute to their important uinque biodiversity and biogeographic significance (Florencio et al. 2021, Borges et al. 2022).

During this project, the Island of Terceira (the third largest) was surveyed. Ten sampling plots were selected in areas of native vegetation, predominantly dominated by endemic species such as Juniperus brevifolia, Erica azorica, Laurus azorica and Ilex azorica, with currently some spread of invasive species like Hedychium gardnerianum. Ten additional plots were situated in secondary forests, predominantly characterised by Pittosporum undulatum and Hedychium gardnerianum, yet exhibiting indications of endemic and native ferns, such as Dryopteris azorica and Diplazium caudatum.

Design description: 

The experimental design comprised a 90-day sampling period, spanning from mid-June to mid-September 2024 (summer period), across all twenty sites. The sampling method employed was SLAM traps, with a maximum of three traps deployed at each site. In locations where feasible, these traps were positioned at varying heights within the forest, specifically at 0% (ground trap, hereafter GRD), 50% (understorey trap, UND) and 75% (canopy trap, CAN) of the maximum canopy height. In the event that the understorey trap was separated from the other two traps by less than 1 vertical metre, this trap was not set up.

Additionally, 14 Pitfall traps (hereafter EPI) were randomly set up at each site for a duration of 14 days, starting in July and concluding in August 2024.

Funding: 

Sebastien Lhoumeau was funded by the project ”The impact of habitat structure change on arthropod food web complexity in Azorean forests” (PhD grant M3.1.a/F/012/2022).

Additional funding come for :

Portal da Biodiversidade dos Açores (2022-2023) - PO Azores Project - M1.1.A/INFRAEST CIENT/001/2022;

FCT-UIDB/00329/2020-2024 (Thematic Line 1 – integrated ecological assessment of environmental change on biodiversity) (2019-2024);

Science and Technology Foundation (FCT) - MACRISK-Trait-based prediction of extinction risk and invasiveness for Northern Macaronesian arthropods (FCT-PTDC/BIA-CBI/0625/2021).

Open access was funded by the project FCT-UID/00329/2025, Centre for Ecology, Evolution and Environmental Changes (CE3C).

Sampling methods

Description: 

A total of twenty 20 m x 20 m plots were sampled in one island from the Archipelago (Terceira). Ten of these plots were set up within the most well-preserved forests in this island, having limited human disturbance (Borges et al. 2017). The native forest is dominated by endemic vegetation, such as Juniperus brevifolia, Erica azorica, Laurus azorica and Ilex azorica (see Borges et al. (2017) for more details). Ten other plots are in secondary forests, which are dominated by exotic and invasive trees.

Sampling description: 

Passive flight interception SLAM traps (Sea, Land and Air Malaise trap, Fig. 1) were used to sample the plots, with three traps being set up at each plot at different height within the forest. Traps are 110 × 110 × 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. As a result, 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, Lhoumeau and Borges 2023). The traps samples were collected after three months in the studied sites.

Figure 1.  

Picture of the set-up of the three SLAM traps within the exotic forest (site TER-EXO-T04) (Credit: Sébastien Lhoumeau).

We completed the sampling by using 14 passive Pitfall traps (Fig. 2) randomly distributed within the plots to sample the epigean fauna. Traps have a 5 cm opening diameter and filled with ethylene glycol. Pitfall traps were collected after two weeks (14 nights) of continuous operation.

Figure 2.  

Picture of a Pitfall trap set-up (the protective cover is removed) (Credit: Sébastien Lhoumeau).

Quality control: 

All sorted specimens were identified by a taxonomical expert, one of the authors P.A.V.B. and species taxonomic nomenclature and species colonisation status follows Borges et al. (2022).

Geographic coverage

Description: 

Terceira Island, Azores (Portugal), Fig. 3.

Figure 3.  

Location of Terceira Island. For comprehensive details regarding the sampling sites, refer to Table 1. The protected areas data was sourced from UNEP-WCMC (2025), while the land-use data were provided by the Azorean government.

Table 1.
Download as
CSV
XLSX

List of the 20 sampled sites in Terceira.

Information about the habitat, location identifier, locality, decimal coordinates and elevation in metres are provided.

In the habitat, we classify the type of native forest based on Elias et al. (2016): (1) Laurus Submontane Forests, (2) Juniperus-Ilex Montane Forests, (3) Juniperus Montane Woodlands. Exotic forests are dominated by the invasive tree species Pittosporum undulatum.

Elevation data are sourced from OpenTopography (2013).

In locations indicated by the asterisk, only two SLAM traps were installed. The implementation of the understorey trap was rendered unfeasible due to the reduced canopy height.

Habitat type Site code Site name Decimal longitude Decimal latitude Elevation above sea level (m)
Exotic forest TER-EXO-T01 Mata do Estado -27.24 38.697 425
Exotic forest TER-EXO-T02 Matela -27.26 38.7 394
Exotic forest TER-EXO-T04 Serreta 400 -27.352 38.765 376
Exotic forest TER-EXO-T09 Caparica Horses -27.263 38.762 417
Exotic forest TER-EXO-T10 Gruta do Balcões -27.25 38.759 459
Exotic forest TER-PRIBS-T06 Caparica -27.262 38.771 336
Exotic forest TER-PRIBS-T09 Fontinhas -27.138 38.738 256
Exotic forest TER-PRIBS-T15 Agualva -27.193 38.769 367
Exotic forest TER-PRIBS-T27 Gruta Chocolade -27.249 38.779 271
Exotic forest TER-PRIBS-T28 Pico Rachado -27.31 38.769 461
Native forest (1) TER-NFBF-T-01 Morro Assombrado -27.219 38.762 680
Native forest (3) TER-NFBF-T-02 (*) Biscoito da Ferraria -27.233 38.752 590
Native forest (3) TER-NFBF-TP41 Pico Alto -27.207 38.75 673
Native forest (2) TER-NFPG-T-33 Pico Galhardo -27.227 38.734 643
Native forest (2) TER-NFSB-T-07 Lomba -27.29 38.737 683
Native forest (3) TER-NFSB-T164B Santa Bárbara -27.308 38.735 899
Native forest (3) TER-NFSB-TE48 Lagoinha -27.331 38.752 678
Native forest (3) TER-NFSB-TE49 (*) Lagoa do Pinheiro -27.331 38.752 927
Native forest (1) TER-NFTB-T-15 Terra Brava A -27.201 38.736 637
Native forest (1) TER-NFTB-T-18 Terra Brava B -27.197 38.732 679
Coordinates: 

-27.04093 and -27.39698 Latitude; 38.81982 and 38.62170 Longitude.

Taxonomic coverage

Description: 

The following orders and class are covered:

Taxa included:
Rank Scientific Name
kingdom Animalia
phylum Arthropoda
class Insecta
class Arachnida
class Diplopoda
class Chilopoda
order Coleoptera
order Hemiptera
order Psocodea
order Araneae
order Neuroptera
order Hymenoptera
order Thysanoptera
order Archaeognatha
order Opiliones
order Pseudoscorpiones
order Phasmida
order Dermaptera
order Julida
order Blattodea
order Lepidoptera
order Ephemeroptera
order Trichoptera
order Lithobiomorpha
order Geophilomorpha
order Polydesmida
order Strepsiptera

Temporal coverage

Data range: 
2024-6-11 - 2024-9-27.
Notes: 

SLAM traps were collected after three months in the studied sites. Pitfall traps were recovered after two weeks (14 nights) of continuous operation.

Collection data

Collection name: 
Entomoteca Dalberto Teixeira Pombo
Collection identifier: 
DTP
Specimen preservation method: 
Ethanol (96%)

Usage licence

Usage licence: 
Creative Commons Public Domain Waiver (CC-Zero)

Data resources

Data package title: 
Stratified sampling of Azorean forest arthropods
Resource link: 
https://doi.org/10.15468/7aue4t
Alternative identifiers: 
https://www.gbif.org/dataset/d3580ac2-a504-44e0-8e59-de89c430924c; http://ipt.gbif.pt/ipt/resource?r=azores_forest_arthropods
Number of data sets: 
2
Data set name: 
Event table
Character set: 
UTF-8
Download URL: 
http://ipt.gbif.pt/ipt/archive.do?r=azores_forest_arthropods
Data format: 
Darwin Core Archive format
Data format version: 
Version 1.6
Description: 

The dataset was published in the Global Biodiversity Information Facility platform, GBIF (Lhoumeau and Borges 2025). The following data-table includes all the records for which a taxonomic identification of the species was possible. The dataset submitted to GBIF is structured as a sample event dataset that has been published as a Darwin Core Archive (DwCA), which is a standardised format for sharing biodiversity data as a set of one or more data tables. The core data file contains 326 records (eventID). This GBIF IPT (Integrated Publishing Toolkit, Version 2.5.6) archives the data and, thus, serves as the data repository. The data and resource metadata are available for download in the Portuguese GBIF Portal IPT (Lhoumeau and Borges 2025).

Column label Column description
id Unique identification code for sampling event data.
eventID Identifier of the events, unique for the dataset.
samplingProtocol The sampling protocol used to capture the species.
sampleSizeValue The numeric amount of time spent in each sampling.
sampleSizeUnit The unit of the sample size value.
eventDate Date or date range the record was collected.
eventRemarks The verbatim original representation of the date and time information for an Event. In this case, we use the season and year.
habitat The habitat from which the sample was obtained.
locationID Identifier of the location.
islandGroup Name of archipelago, always Azores in the dataset.
island Name of the island, always Terceira in the dataset.
country Country of the sampling site, always Portugal in the dataset.
countryCode ISO code of the country of the sampling site, always PT in the dataset.
stateProvince Name of the region of the sampling site.
municipality Municipality of the sampling site.
locality Name of the locality.
minimumElevationInMetres The lower limit of the range of elevation (altitude, above sea level), in metres.
locationRemarks Details on the locality site.
decimalLatitude Approximate decimal latitude of the trap.
decimalLongitude Approximate decimal longitude of the trap.
geodeticDatum The ellipsoid, geodetic datum or spatial reference system (SRS) upon which the geographic coordinates given in decimalLatitude and decimalLongitude are based, always WGS84 in the dataset.
coordinateUncertaintyInMetres Uncertainty of the coordinates of the centre of the sampling plot.
coordinatePrecision Precision of the coordinates.
georeferenceSources A list (concatenated and separated) of maps, gazetteers or other resources used to georeference the Location, described specifically enough to allow anyone in the future to use the same resources.
Data set name: 
Occurrence table
Character set: 
UTF-8
Download URL: 
http://ipt.gbif.pt/ipt/resource?r=azores_forest_arthropods
Data format: 
Darwin Core Archive format
Data format version: 
Version 1.6
Description: 

The dataset was published in the Global Biodiversity Information Facility platform, GBIF (Lhoumeau and Borges 2025). The following data table includes all the records for which a taxonomic identification of the species was possible. The dataset submitted to GBIF is structured as an occurrence table that has been published as a Darwin Core Archive (DwCA), which is a standardised format for sharing biodiversity data as a set of one or more data tables. The core data file contains 2399 records (occurrenceID). This GBIF IPT (Integrated Publishing Toolkit, Version 2.5.6) archives the data and, thus, serves as the data repository. The data and resource metadata are available for download in the Portuguese GBIF Portal IPT (Lhoumeau and Borges 2025).

Column label Column description
id Unique identification code for species abundance data. Equivalent here to eventID.
type The nature or genre of the resource, as defined by the Dublin Core standard. In our case "PhysicalObject".
licence Reference to the licence under which the record is published.
institutionID The identity of the institution publishing the data.
collectionID The identity of the collection where the specimen are conserved.
collectionID The identity of the collection publishing the data.
institutionCode The code of the institution publishing the data.
collectionCode The code of the collection where the specimens are conserved.
datasetName Name of the dataset.
basisOfRecord The nature of the data record.
recordedBy A list (concatenated and separated) of names of peoples, groups or organisations who performed the sampling in the field.
occurrenceID Identifier of the record, coded as a global unique identifier.
organismQuantity A number or enumeration value for the quantity of organisms.
organismQuantityType The type of quantification system used for the quantity of organisms.
sex The sex and quantity of the individuals captured.
lifeStage The life stage of the organisms captured.
establishmentMeans The process of establishment of the species in the location, using a controlled vocabulary: 'native', 'introduced', 'endemic' or 'indeterminate'.
eventID Identifier of the events, unique for the dataset.
identifiedBy A list (concatenated and separated) of names of people, groups or organisations who assigned the taxon to the record.
dateIdentified The date on which the subject was determined as representing the taxon.
scientificName Complete scientific name including author and year.
kingdom Kingdom name.
phylum Phylum name.
class Class name.
order Order name.
family Family name.
genus Genus name.
specificEpithet Specific epithet
infraspecificEpithet Infraspecific epithet.
taxonRank Lowest taxonomic rank of the record.
scientificNameAuthorship Name of the author of the lowest taxon rank included in the record.
identificationRemarks Information about morphospecies identification (code in Dalberto Teixeira Pombo Collection).

Additional information

We collected a total of 32,797 specimens of terrestrial arthropods using SLAM and Pitfall traps deployed across diverse forest strata in native and exotic forests. These specimens, representing the classes Arachnida, Diplopoda, Chilopoda and Insecta, provide a comprehensive snapshot of Azorean arthropod diversity. Of the total collected, 18,372 individuals (56%) were identified at the species or subspecies level — comprising 12,745 adults and 5,627 juveniles (Table 2).

Table 2.
Download as
CSV
XLSX

Number of individuals sampled and identified at the species or subspecies level.

CAN: canopy layer, UND: understorey layer, GRD: ground layer, EPI: epigean layer.

Epigean layer is sampled with pitfall traps whereas all the other layers are sampled with SLAM traps.

Establishment (species colonisation status) data is according to Borges et al. (2022).

Class Order Scientific Name Establishment EPI GRD UND CAN
Arachnida Araneae Acorigone acoreensis (Wunderlich, 1992) endemic 2 17 6 5
Arachnida Araneae Agalenatea redii (Scopoli, 1763) introduced 0 2 0 0
Arachnida Araneae Agyneta decora (O. Pickard-Cambridge, 1871) introduced 2 1 0 0
Arachnida Araneae Canariphantes acoreensis (Wunderlich, 1992) endemic 207 7 0 0
Arachnida Araneae Cheiracanthium erraticum (Walckenaer, 1802) introduced 0 3 1 2
Arachnida Araneae Clubiona terrestris Westring, 1851 introduced 0 8 0 0
Arachnida Araneae Cryptachaea blattea (Urquhart, 1886) introduced 0 11 2 0
Arachnida Araneae Dysdera crocata C. L. Koch, 1838 introduced 119 18 2 0
Arachnida Araneae Erigone atra Blackwall, 1833 introduced 1 0 0 0
Arachnida Araneae Erigone dentipalpis (Wider, 1834) introduced 0 1 0 0
Arachnida Araneae Ero furcata (Villers, 1789) introduced 32 25 10 6
Arachnida Araneae Gibbaranea occidentalis Wunderlich, 1989 endemic 2 264 289 280
Arachnida Araneae Lasaeola oceanica Simon, 1883 endemic 0 3 0 0
Arachnida Araneae Lathys dentichelis (Simon, 1883) native non-endemic 0 2 0 4
Arachnida Araneae Leucognatha acoreensis Wunderlich, 1992 endemic 4 21 27 19
Arachnida Araneae Macaroeris cata (Blackwall, 1867) native non-endemic 0 24 11 15
Arachnida Araneae Macaroeris diligens (Blackwall, 1867) native non-endemic 0 6 5 11
Arachnida Araneae Mangora acalypha (Walckenaer, 1802) introduced 0 0 0 1
Arachnida Araneae Metellina merianae (Scopoli, 1763) introduced 0 7 0 0
Arachnida Araneae Microlinyphia johnsoni (Blackwall, 1859) native non-endemic 0 84 9 4
Arachnida Araneae Ostearius melanopygius (O. Pickard-Cambridge, 1880) introduced 0 1 0 0
Arachnida Araneae Palliduphantes schmitzi (Kulczynski, 1899) native non-endemic 5 2 1 0
Arachnida Araneae Pardosa acorensis Simon, 1883 endemic 5 0 1 1
Arachnida Araneae Pisaura acoreensis Wunderlich, 1992 endemic 8 26 18 62
Arachnida Araneae Porrhoclubiona decora (Blackwall, 1859) native non-endemic 0 17 2 5
Arachnida Araneae Porrhoclubiona genevensis (L. Koch, 1866) introduced 1 16 0 1
Arachnida Araneae Porrhomma borgesi Wunderlich, 2008 endemic 2 0 2 0
Arachnida Araneae Rugathodes acoreensis Wunderlich, 1992 endemic 12 108 115 27
Arachnida Araneae Savigniorrhipis acoreensis Wunderlich, 1992 endemic 0 73 55 36
Arachnida Araneae Segestria florentina (Rossi, 1790) introduced 0 1 0 0
Arachnida Araneae Steatoda nobilis (Thorell, 1875) native non-endemic 0 1 1 0
Arachnida Araneae Tenuiphantes miguelensis (Wunderlich, 1992) native non-endemic 304 18 1 1
Arachnida Araneae Tenuiphantes tenuis (Blackwall, 1852) introduced 27 45 0 1
Arachnida Araneae Theridion melanostictum O. Pickard-Cambridge, 1876 introduced 0 1 0 0
Arachnida Araneae Theridion musivivum Schmidt, 1956 native non-endemic 0 4 0 0
Arachnida Araneae Walckenaeria grandis (Wunderlich, 1992) endemic 2 13 0 0
Arachnida Araneae Xysticus cor Canestrini, 1873 native non-endemic 0 1 2 5
Arachnida Opiliones Leiobunum blackwalli Meade, 1861 native non-endemic 335 1412 279 174
Arachnida Pseudoscorpiones Chthonius ischnocheles (Hermann, 1804) introduced 26 2 0 0
Arachnida Pseudoscorpiones Ephippiochthonius tetrachelatus (Preyssler, 1790) introduced 0 1 0 0
Arachnida Pseudoscorpiones Neobisium maroccanum Beier, 1930 introduced 0 8 0 0
Chilopoda Geophilomorpha Geophilus truncorum Bergsøe & Meinert, 1866 native non-endemic 1 0 0 0
Chilopoda Geophilomorpha Strigamia crassipes (C.L. Koch, 1835) native non-endemic 2 1 0 0
Chilopoda Lithobiomorpha Lithobius pilicornis pilicornis Newport, 1844 native non-endemic 91 1 0 0
Diplopoda Julida Blaniulus guttulatus (Fabricius, 1798) introduced 176 0 0 0
Diplopoda Julida Cylindroiulus propinquus (Porat, 1870) introduced 10 0 0 0
Diplopoda Julida Nopoiulus kochii (Gervais, 1847) introduced 11 1 0 0
Diplopoda Julida Ommatoiulus moreleti (Lucas, 1860) introduced 58 22 7 1
Diplopoda Julida Proteroiulus fuscus (Am Stein, 1857) introduced 3 0 0 0
Diplopoda Polydesmida Oxidus gracilis (C.L. Koch, 1847) introduced 3 0 0 0
Diplopoda Polydesmida Polydesmus coriaceus Porat, 1870 introduced 13 0 0 0
Insecta Archaeognatha Dilta saxicola (Womersley, 1930) native non-endemic 0 4 0 2
Insecta Archaeognatha Trigoniophthalmus borgesi Mendes, Gaju, Bach & Molero, 2000 endemic 1 160 21 105
Insecta Blattodea Zetha simonyi (Krauss, 1892) native non-endemic 3 142 50 55
Insecta Coleoptera Amischa analis (Gravenhorst, 1802) indeterminate 0 2 0 0
Insecta Coleoptera Anaspis proteus Wollaston, 1854 native non-endemic 0 114 74 73
Insecta Coleoptera Anisodactylus binotatus (Fabricius, 1787) introduced 0 0 1 0
Insecta Coleoptera Anobium punctatum (De Geer, 1774) introduced 0 1 0 0
Insecta Coleoptera Anotylus nitidifrons (Wollaston, 1871) indeterminate 270 1 0 0
Insecta Coleoptera Atheta fungi (Gravenhorst, 1806) indeterminate 3 3 0 0
Insecta Coleoptera Atheta pasadenae Bernhauer, 1906 indeterminate 0 1 0 0
Insecta Coleoptera Athous azoricus Platia & Gudenzi, 2002 endemic 3 12 0 0
Insecta Coleoptera Brassicogethes aeneus (Fabricius, 1775) introduced 0 1 1 0
Insecta Coleoptera Calacalles subcarinatus (Israelson, 1984) endemic 0 25 12 2
Insecta Coleoptera Carpelimus corticinus (Gravenhorst, 1806) indeterminate 6 8 0 0
Insecta Coleoptera Carpelimus troglodytes troglodytes (Erichson, 1840) indeterminate 2 0 0 0
Insecta Coleoptera Cartodere nodifer (Westwood, 1839) introduced 0 3 0 0
Insecta Coleoptera Catops coracinus Kellner, 1846 native non-endemic 1 6 1 0
Insecta Coleoptera Cedrorum azoricus azoricus Borges & A.Serrano, 1993 endemic 27 0 0 0
Insecta Coleoptera Cephennium validum Assing & Meybohm, 2021 native non-endemic 1 0 0 0
Insecta Coleoptera Cercyon haemorrhoidalis (Fabricius, 1775) introduced 1 0 0 0
Insecta Coleoptera Coccinella undecimpunctata undecimpunctata Linnaeus, 1758 introduced 0 1 1 0
Insecta Coleoptera Coccotrypes carpophagus (Hornung, 1842) introduced 0 1 1 0
Insecta Coleoptera Creophilus maxillosus maxillosus (Linnaeus, 1758) indeterminate 0 0 1 0
Insecta Coleoptera Cryptamorpha desjardinsii (Guérin-Méneville, 1844) introduced 0 1 0 1
Insecta Coleoptera Drouetius borgesi borgesi (Machado, 2009) endemic 1 67 3 1
Insecta Coleoptera Dryops algiricus (Lucas, 1846) native non-endemic 1 1 1 1
Insecta Coleoptera Epitrix hirtipennis (Melsheimer, 1847) introduced 0 1 0 0
Insecta Coleoptera Gonipterus platensis (Marelli, 1926) introduced 0 2 0 0
Insecta Coleoptera Heteroderes azoricus (Tarnier, 1860) endemic 0 3 0 1
Insecta Coleoptera Heteroderes vagus Candèze, 1893 introduced 1 0 0 0
Insecta Coleoptera Kalcapion semivittatum semivittatum (Gyllenhal, 1833) indeterminate 0 1 0 0
Insecta Coleoptera Longitarsus kutscherai (Rye, 1872) introduced 0 3 0 0
Insecta Coleoptera Mecinus pascuorum (Gyllenhal, 1813) introduced 0 1 2 0
Insecta Coleoptera Notothecta dryochares (Israelson, 1985) endemic 1 52 8 2
Insecta Coleoptera Ocypus aethiops (Waltl, 1835) indeterminate 39 0 0 0
Insecta Coleoptera Ocys harpaloides (Audinet-Serville, 1821) native non-endemic 0 0 5 0
Insecta Coleoptera Paranchus albipes (Fabricius, 1796) introduced 95 0 1 0
Insecta Coleoptera Phloeonomus punctipennis Thomson, 1867 indeterminate 1 2 0 0
Insecta Coleoptera Phyllotreta striolata (Fabricius, 1803) introduced 0 0 1 1
Insecta Coleoptera Popillia japonica Newman, 1838 introduced 0 4 0 0
Insecta Coleoptera Proteinus atomarius Erichson, 1840 indeterminate 2 2 0 0
Insecta Coleoptera Pseudoophonus rufipes (De Geer, 1774) introduced 1 0 0 0
Insecta Coleoptera Pseudophloeophagus tenax borgesi Stüben, 2022 endemic 2 74 27 15
Insecta Coleoptera Psylliodes marcida (Illiger, 1807) native non-endemic 0 1 0 0
Insecta Coleoptera Sitona discoideus Gyllenhal, 1834 introduced 0 2 0 0
Insecta Coleoptera Sphenophorus abbreviatus (Fabricius, 1787) introduced 1 0 0 0
Insecta Coleoptera Stelidota geminata (Say, 1825) introduced 47 0 1 0
Insecta Coleoptera Stilbus testaceus (Panzer, 1797) native non-endemic 0 1 0 0
Insecta Coleoptera Tachyporus chrysomelinus (Linnaeus, 1758) indeterminate 0 1 0 0
Insecta Coleoptera Tachyporus nitidulus (Fabricius, 1781) indeterminate 1 0 0 0
Insecta Coleoptera Tarphius relictus Borges & Serrano, 2017 endemic 3 0 0 0
Insecta Coleoptera Trechus terrabravensis Borges, Serrano & Amorim, 2004 endemic 12 0 0 0
Insecta Coleoptera Xyleborinus alni Nijima, 1909 introduced 0 0 1 0
Insecta Dermaptera Euborellia annulipes (Lucas, 1847) introduced 0 6 0 0
Insecta Dermaptera Forficula auricularia Linnaeus, 1758 introduced 1 3 0 0
Insecta Ephemeroptera Cloeon dipterum (Linnaeus, 1761) native non-endemic 0 0 1 0
Insecta Hemiptera Acalypta parvula (Fallén, 1807) native non-endemic 0 1 0 0
Insecta Hemiptera Acizzia uncatoides (Ferris & Klyver, 1932) introduced 0 512 82 62
Insecta Hemiptera Anthocoris nemoralis (Fabricius, 1794) native non-endemic 0 1 0 0
Insecta Hemiptera Aphrodes hamiltoni Quartau & Borges, 2003 endemic 22 5 0 0
Insecta Hemiptera Buchananiella continua (White, 1880) introduced 0 1 0 0
Insecta Hemiptera Campyloneura virgula (Herrich-Schaeffer, 1835) native non-endemic 1 37 35 17
Insecta Hemiptera Cinara juniperi (De Geer, 1773) native non-endemic 0 90 3 7
Insecta Hemiptera Cixius azoterceirae Remane & Asche, 1979 endemic 6 1926 915 1304
Insecta Hemiptera Cyphopterum adscendens (Herrich-Schäffer, 1835) native non-endemic 0 140 73 23
Insecta Hemiptera Eupteryx azorica Ribaut, 1941 endemic 0 2 0 2
Insecta Hemiptera Eupteryx filicum (Newman, 1853) native non-endemic 0 20 4 0
Insecta Hemiptera Fulvius borgesi Chérot, Ribes & Gorczyca, 2006 introduced 0 0 0 1
Insecta Hemiptera Heterotoma planicornis (Pallas, 1772) native non-endemic 0 1 0 0
Insecta Hemiptera Kelisia ribauti Wagner, 1938 native non-endemic 0 10 4 3
Insecta Hemiptera Kleidocerys ericae (Horváth, 1909) native non-endemic 0 329 13 10
Insecta Hemiptera Loricula coleoptrata (Fallén, 1807) native non-endemic 0 4 4 2
Insecta Hemiptera Megamelodes quadrimaculatus (Signoret, 1865) native non-endemic 43 0 0 1
Insecta Hemiptera Monalocoris filicis (Linnaeus, 1758) native non-endemic 0 112 15 10
Insecta Hemiptera Nabis pseudoferus ibericus Remane, 1962 native non-endemic 0 9 4 4
Insecta Hemiptera Orius laevigatus laevigatus (Fieber, 1860) native non-endemic 0 1 0 0
Insecta Hemiptera Pilophorus perplexus Douglas & Scott, 1875 native non-endemic 0 0 42 0
Insecta Hemiptera Pinalitus oromii J. Ribes, 1992 endemic 0 34 29 48
Insecta Hemiptera Rhopalosiphoninus latysiphon (Davidson, 1912) introduced 10 0 0 0
Insecta Hemiptera Saldula palustris (Douglas, 1874) native non-endemic 0 0 1 1
Insecta Hemiptera Scolopostethus decoratus (Hahn, 1833) native non-endemic 0 0 1 0
Insecta Hemiptera Siphanta acuta (Walker, 1851) introduced 0 85 7 8
Insecta Hemiptera Strophingia harteni Hodkinson, 1981 endemic 0 23 6 11
Insecta Hemiptera Trioza laurisilvae Hodkinson, 1990 native non-endemic 1 329 376 821
Insecta Hymenoptera Hypoponera eduardi (Forel, 1894) native non-endemic 0 0 1 2
Insecta Hymenoptera Lasius grandis Forel, 1909 native non-endemic 52 171 13 20
Insecta Hymenoptera Monomorium carbonarium (Smith, 1858) native non-endemic 0 0 0 3
Insecta Hymenoptera Tetramorium caespitum (Linnaeus, 1758) native non-endemic 0 4 0 0
Insecta Lepidoptera Argyresthia atlanticella Rebel, 1940 endemic 4 0 0 0
Insecta Lepidoptera Ascotis fortunata azorica Pinker, 1971 endemic 1 0 0 0
Insecta Lepidoptera Mythimna unipuncta (Haworth, 1809) native non-endemic 1 0 0 0
Insecta Neuroptera Hemerobius azoricus Tjeder, 1948 endemic 0 64 49 34
Insecta Phasmida Carausius morosus (Sinéty, 1901) introduced 0 3 0 0
Insecta Psocodea Atlantopsocus adustus (Hagen, 1865) native non-endemic 0 14 11 6
Insecta Psocodea Bertkauia lucifuga (Rambur, 1842) native non-endemic 0 16 4 2
Insecta Psocodea Ectopsocus briggsi McLachlan, 1899 introduced 2 262 71 104
Insecta Psocodea Ectopsocus strauchi Enderlein, 1906 native non-endemic 0 1 1 0
Insecta Psocodea Elipsocus azoricus Meinander, 1975 endemic 0 113 68 40
Insecta Psocodea Elipsocus brincki Badonnel, 1963 endemic 0 56 37 146
Insecta Psocodea Lachesilla greeni (Pearman, 1933) introduced 0 0 0 2
Insecta Psocodea Trichopsocus clarus (Banks, 1908) native non-endemic 2 307 90 33
Insecta Psocodea Valenzuela burmeisteri (Brauer, 1876) native non-endemic 0 47 17 5
Insecta Psocodea Valenzuela flavidus (Stephens, 1836) native non-endemic 2 1089 266 214
Insecta Strepsiptera Elenchus tenuicornis (Kirby, 1815) native non-endemic 0 0 0 1
Insecta Thysanoptera Anisopilothrips venustulus (Priesner, 1923) introduced 0 1 0 0
Insecta Thysanoptera Ceratothrips ericae (Haliday, 1836) native non-endemic 0 61 13 7
Insecta Thysanoptera Heliothrips haemorrhoidalis (Bouché, 1833) introduced 0 13 2 1
Insecta Thysanoptera Hercinothrips bicinctus (Bagnall, 1919) introduced 0 1 0 0
Insecta Thysanoptera Hoplothrips corticis (De Geer, 1773) native non-endemic 0 65 49 27
Insecta Trichoptera Limnephilus atlanticus Nybom, 1948 endemic 7 3 5 0

In general, the most abundant order identified was Hemiptera, with 21,939 recorded specimens, underscoring its prevalence in these forest ecosystems. Although not the most abundant, Coleoptera emerged as the most taxonomically diverse group, being represented by 19 distinct families and 50 species and sub-species. The ten most abundant species are predominantly endemic and native non-endemic taxa, with only two introduced species amongst them. This comprehensive dataset significantly augments the existing baseline knowledge on Azorean arthropods and offers valuable insights into the vertical distribution of species abundance within both native and exotic forests.

The dataset provides strong evidence that arthropod communities are structured differently along the vertical gradient in native and exotic forests (Fig. 4). When comparing these two types of forests, we found that distribution of arthropod abundance vary significantly across the three forest strata: ground, understorey and canopy (Table 3).

Table 3.
Download as
CSV
XLSX

Pairwise comparisons of adult arthropods abundance between exotic forest and native forest across different strata (EPI: epigean layer, GRD: ground layer, UND: understorey layer, CAN: canopy layer) using Wilcoxon rank sum tests.

The table presents the sample sizes (n1 and n2), test statistic values and significance levels (*p < 0.05, **p < 0.01, ns = not significant) as well as the effect size and magnitude, based on 1000 replications for the significant comparisons.

Strata Forest type 1 Forest type 2 n1 n2 W Significance Effect size Magnitude
EPI Exotic forest Native forest 10 10 62.5 ns --- ---
GRD Exotic forest Native forest 10 10 84 ** 0.57 large
UND Exotic forest Native forest 10 8 15 * 0.52 large
CAN Exotic forest Native forest 10 10 9 ** 0.69 large
Figure 4.  

Abundance of arthropods across different forest strata in exotic and native forests.

The x-axis represents the total number of arthropods collected and identified, while the y-axis indicates the sampled strata (EPI: epigean, GRD: ground, UND: understorey, CAN: canopy). Points represent individual site values for a given forest type. Bars are colour-coded to distinguish between exotic forests (yellow) and native forests (green).

Kruskal-Wallis tests revealed statistically significant differences in adult abundance total across the strata of exotic forest (χ2(3) = 24.2, n = 40, p < 0.001) and native forest (χ2(3) = 20.8, n = 38, p < 0.001).

In exotic forest, Kruskal-Wallis effect size (η2[H]) for the difference in adult abundance total was 0.59 (95% CI [0.35, 0.80], n = 40), indicating a large effect. In native forest, the effect was also large with 0.52 (95% CI [0.29, 0.73]).

One of the most striking findings is the more even distribution of arthropods across the vertical strata in native forests compared to exotic forests, where abundance is disproportionately concentrated in the ground layer (Fig. 4).

Native forests offer a greater number of distinct ecological niches at varying heights, thus allowing for a greater degree of vertical partitioning amongst arthropod communities (Basset et al. 2003, Basset et al. 2015, Xing et al. 2023). Therefore, it was hypothesised that the distribution of the overall arthropod assemblage would differ more from one strata to another. However, the observed homogeneity in the abundance distribution could be attributed to the relatively low canopy height within the study plots (Dias et al. 2004, Elias et al. 2016). The well-developed understorey and dense canopy create a structurally complex environment that supports a high diversity of arthropods. The presence of climbing vegetation, epiphytes and diverse leaf architecture contributes to habitat complexity and homogeneity by providing multiple pathway for species to move in the ecosystems. However, when distinguishing the overall arthropod assemblage by order, we detected that native forests are supporting a higher proportion of canopy- and understorey-associated taxa (Fig. 5). Similarly to a study conducted in Amazonian forest by de Souza Amorim et al. (2022), groups such as Araneae, Hemiptera and Hymenoptera (formicidae) show significantly higher relative abundance in the upper strata (Table 4), suggesting that these layers serve as critical habitat for these functional groups (see Arvidsson et al. (2022) on spider's web). The increased presence of predators (e.g. spiders) in the canopy and understorey of native forests may indicate a more complex food web structure, with stronger top-down regulation of herbivore populations (Martinez‐Almoyna et al. 2024, Wildermuth et al. 2024).

Table 4.
Download as
CSV
XLSX

Statistical comparison of arthropod order abundance between exotic and native forests across different forest strata (EPI: epigean layer, GRD: ground layer, UND: understorey layer, CAN: canopy layer).

n1 and n2 represent sample sizes for exotic and native forests, respectively. p-values are derived from statistical tests (Wilcoxon rank sum tests), with significance levels indicated as: ns (not significant), * (p < 0.05), ** (p < 0.01), *** (p < 0.001).

Order Strata n1 n2 W p-value Significance
Araneae EPI 10 10 31 0.162 ns
Araneae GRD 10 10 19 0.0185 *
Araneae UND 10 8 2 0.00081 ***
Araneae CAN 10 10 35 0.272 ns
Archaeognatha EPI 10 10 45 0.368 ns
Archaeognatha GRD 10 10 31 0.101 ns
Archaeognatha UND 10 8 25 0.0474 *
Archaeognatha CAN 10 10 40 0.399 ns
Blattodea GRD 10 10 42.5 0.572 ns
Blattodea UND 10 8 20 0.0174 *
Blattodea CAN 10 10 46 0.67 ns
Coleoptera EPI 10 10 81 0.0211 *
Coleoptera GRD 10 10 41 0.529 ns
Coleoptera UND 10 8 68 0.0117 *
Coleoptera CAN 10 10 100 0.000178 ***
Hemiptera EPI 10 10 5.5 0.00038 ***
Hemiptera GRD 10 10 59 0.529 ns
Hemiptera UND 10 8 27 0.274 ns
Hemiptera CAN 10 10 13 0.00578 **
Hymenoptera EPI 10 10 80 0.00597 **
Hymenoptera GRD 10 10 59 0.517 ns
Hymenoptera UND 10 8 39 0.962 ns
Hymenoptera CAN 10 10 73 0.0626 ns
Julida EPI 10 10 52 0.901 ns
Julida GRD 10 10 55 0.69 ns
Julida UND 10 8 35 0.314 ns
Lithobiomorpha EPI 10 10 14.5 0.00789 **
Lithobiomorpha GRD 10 10 45 0.368 ns
Neuroptera GRD 10 10 51 0.968 ns
Neuroptera UND 10 8 57 0.138 ns
Neuroptera CAN 10 10 82 0.0164 *
Opiliones EPI 10 10 60.5 0.394 ns
Opiliones GRD 10 10 75 0.062 ns
Opiliones UND 10 8 37 0.823 ns
Opiliones CAN 10 10 66.5 0.22 ns
Psocodea EPI 10 10 65 0.0779 ns
Psocodea GRD 10 10 54 0.796 ns
Psocodea UND 10 8 60 0.0831 ns
Psocodea CAN 10 10 77 0.0433 *
Thysanoptera GRD 10 10 66 0.238 ns
Thysanoptera UND 10 8 63.5 0.0325 *
Thysanoptera CAN 10 10 47 0.843 ns
Figure 5.  

Arthropod vertical profiles in exotic and native forests for the 12 most abundant order sampled and identified.

Each panel represents the distribution of the relative abundance (%) of a given order to the total number of individuals sampled in a forest strata (EPI: epigean, GRD: ground, UND: understorey, CAN: canopy) of exotic forests (yellow) and native forests (green).

In the Azores, exotic forests are dominated by fast-growing, homogeneous tree species and lack the complex understorey and dense canopy of native forests (Connor et al. 2012, Borges Silva et al. 2017, Borges Silva et al. 2018). It is hypothesised that the combination of elevated canopy height and an absence of vertically structural elements may lead to a heightened degree of microclimatic differentiation, which, in turn, may result in a more pronounced vertical stratification within arthropod communities. Additionally, arthropod abundance is significantly higher in the ground layer of exotic forests compared to native forests (Table 3), suggesting that these simplified forest structures concentrate arthropod activity near the forest floor. Many arthropod orders, including detritivores (Julida, Lithobiomorpha) and scavengers (Psocodea), concentrated in the ground layer (Fig. 5). The significantly higher abundance of these groups in the lower strata (Table 4) suggests that exotic forests may be more reliant on decomposition-based energy pathways rather than complex trophic interactions involving arboreal predators and herbivores. This shift could have important implications for ecosystem functioning, potentially leading to altered nutrient cycling and reduced ecological resilience. In addition, the number of specimens sampled from the ground layer in exotic forests might be link to the invasion pattern previously documented by Cardoso et al. (2007), where most of the species appeared to be non-indigenous in this ecosystem.

Overall, our study present, for the first time, a comprehensive stratified survey of forest arthropods in two different forest ecosystem in the Azores Archipelago. The significant differences observed in both overall abundance and order-level composition across strata provide strong evidence that these two forest type are not ecologically equivalent highlighting the need to preserve native forests and enhance vertical complexity in exotic forest to sustain arthropod biodiversity and ecosystem services in forested landscapes. Additionally, future studies should assess how forest structure, microclimatic conditions and resource availability shape arthropod vertical distribution.

Acknowledgements

This study was only possible due to the financial support of several projects for acquiring the SLAM traps, namely:

Portal da Biodiversidade dos Açores (2022-2023) - PO Azores Project - M1.1.A/INFRAEST CIENT/001/2022;

FCT-UIDB/00329/2020-2024 (Thematic Line 1 – integrated ecological assessment of environmental change on biodiversity) (2019-2024);

Science and Technology Foundation (FCT) - MACRISK-Trait-based prediction of extinction risk and invasiveness for Northern Macaronesian arthropods (FCT-PTDC/BIA-CBI/0625/2021).

SLwas supported by the PhD Grant ”The impact of habitat structure change on arthropod food web complexity in Azorean forests” (PhD grant M3.1.a/F/012/2022).

Open access was funded by the project FCT-UID/00329/2025, Centre for Ecology, Evolution and Environmental Changes (CE3C).

Author contributions

SL: Conceptualisation; Research (field and laboratory work); Data Curation; Darwin Core dataset preparation; Formal analysis and interpretation; manuscript writing and revision.

PAVB: Conceptualisation; Methodology; Research (field and laboratory work); Resources; Data Curation; Darwin Core dataset preparation; Formal analysis and interpretation; manuscript writing and revision.

AL: Laboratory work, manuscript revision.

All the remaining authors participated in research (field and laboratory work) and manuscript revision.

References

login to comment