DOI: 10.5061/dryad.0vt4b8gvh
title: Multiscale analysis of canopy arthropod diversity in a volcanically fragmented landscape

description: Dataset and code associated with the article "Multiscale analysis of
 canopy arthropod diversity in a volcanically fragmented landscape"
 (Tielens et al 2019, Ecosphere). Article abstract: Habitat fragmentation
 resulting in habitat loss and increased isolation is a dominant driver of
 global species declines. Habitat isolation and connectivity vary across
 scales, and understanding how con- nectivity affects biodiversity can be
 challenging because the relevant scale depends on the taxa involved. A
 multiscale analysis can provide insight in biodiversity patterns across
 spatial scale when information on dispersal ability is not available, in
 particular for community-level studies focusing on multiple taxa. In this
 study, we examine the relationship between arthropod diversity, patch
 area, and connectivity using a mul- tiscale approach. We make use of a
 natural experiment on Hawai‘i Island, where historic volcanic activity has
 transformed contiguous native forests to lava matrix and discrete forest
 patches. This landscape of patches has persisted for 150 yr, and we
 selected 10,000 ha consisting of 863 patches to analyze landscape
 connectivity using a graph theory approach. We collected arthropod samples
 from Metrosideros polymor- pha tree canopies in 34 forest patches during
 multiple years. We analyzed the relationship of arthropod diversity with
 area, as well as with connectivity across increasing scales, or dispersal
 threshold distances. In contrast to well-established ecological theory as
 well as prior work on birds and fungi in this system, we did not find
 support for a canonical species–area relationship. Next, we calculated
 connectivity across spa- tial scales and found lower Shannon diversity
 with higher connectivity at small scales, but no effect at increased
 dispersal threshold distances. We examined the landscape structure and
 found all habitat patches connected into three subnetworks at a 350 m
 threshold distance. All patches were connected at 700 m threshold
 distance, indicating structural dispersal limitation only at small scales.
 Our findings sug- gest that canopy arthropods are not dispersal limited at
 scales shown to impact both soil fungi and birds in this system. Instead,
 Hawaiian canopy arthropods may perceive the landscape as a connected area
 where discrete forest patches and the early-successional matrix contribute
 resources that vary spatially with regard to habitat quality. We argue for
 the utility of multiscale approaches, and the importance of examin- ing
 maintenance of biodiversity in fragmented landscapes that persist for
 hundreds of years.
description: This dataset consists of arthropods that were sampled from
 <em>Metrosideros polymorpha </em>outer canopy in native mesic
 forests on Hawai'i Island, during 2009 and 2010. See article for
 sampling details. The study landscape was located on
 the northeast flank of Mauna Loa in the Upper Waiakea Forest Reserve on
 Hawai‘i Island (19°38–41′ N, 155°20–23′ W). We also
 include a dataset of connectivity metrics for the forest patches (kipuka).
 We quantified connectivity using habitat availability (reachability)
 metrics based on the integral index of connectivity (IIC; Pascual‐Hortal
 and Saura 2006, Saura and Rubio 2010). See article for further
 details.