Known species from the High Arctic, Low Arctic, and Sub-Arctic, based on records from 1990 to 2022. Additional unknown species are likely present. Geographical Distribution Includes Arctic regions of eight political jurisdictions. Associated article is published in the 2022 Arctic Report Card essay entitled Arctic Pollinators by Burns et al.

Temporal trends of arthropod abundance, 1996–2009. Estimated by the number of individuals caught per trap per day during the season from four different pitfall trap plots, each consisting of eight (1996–2006) or four (2007–2009) traps. Modified from Høye et al. 2013. STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 41 - Figure 3.16

Population trends for springtails in Empetrum nigrum plant community in Kobbefjord, Greenland, 2007–2017. (a) mean population abundance of total Collembola in individuals per square metre, (b) mean number of species per sample, and (c) Shannon-Wiener diversity index per sample. Vertical error bars are standard errors of the mean. Solid lines indicate significant regression lines. Modified from Gillespie et al. 2020a. STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 40 - Figure 3.13

Trends in total abundance of moths and species richness, from two locations in Iceland, 1995–2016. Trends differ between locations. The solid and dashed straight lines represent linear regression lines which are significant or non-significant, respectively. Modified from Gillespie et al. 2020a. STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 41 - Figure 3.14

Conceptual model of the FECs and processes mediated by more than 2,500 species of Arctic arthropods known from Greenland, Iceland, Svalbard, and Jan Mayen. STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 37- Figure 3.7

Trends in four muscid species occurring at Zackenberg Research Station, east Greenland, 1996–2014. Declines were detected in several species over five or more years. Significant regression lines drawn as solid. Non-significant as dotted lines. Modified from Gillespie et al. 2020a. (in the original figure six species showed a statistically significant decline, seven a non-significant decline and one species a non-significant rise) STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 39 - Figure 3.11

Temporal trends of arthropod abundance for three habitat types at Zackenberg Research Station, Greenland, 1996–2016. Data are grouped as the FEC ‘arthropod prey for vertebrates’ and separated by habitat type. Solid lines indicate significant regression lines at the p<0.05. Modified from Gillespie et al. 2020a. STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 39 - Figure 3.9

The diagram indicates the number of species in each FEC for the North Atlantic region of the Arctic (circular outline) and the overlap between the five CBMP–Terrestrial Plan FECs and the additional ‘predators’ FEC. The link width indicates the number of species linking two FECs. The larger the link the more species that are found in linking FECs. Modified from Gillespie et al. 2020a. STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 38 - Figure 3.8

The baseline survey and ongoing monitoring required to adequately describe Arctic arthropod biodiversity and to identify trends is largely lacking. Although some existing publications reporting long-term and extensive sampling exist, they are limited in species level information, taxonomic coverage and/or geographic location/extent (Figure 3-19) STATE OF THE ARCTIC TERRESTRIAL BIODIVERSITY REPORT - Chapter 3 - Page 44 - Figure 3.19

The Turkey Lakes Watershed (TLW) Study was established in 1979 by several federal government departments (Natural Resources Canada, Environment and Climate Change Canada, and Fisheries and Oceans Canada) to study the impacts of acid rain on aquatic and forest ecosystems but has since expanded to include other research on toxic contaminants, forest harvesting, habitat modification, and climate change. The TLW is a mixed hardwood forest with a 10.5 km squared area in the Canada Shield that drains into Lake Superior, and has been the focus of many interdisciplinary, whole-ecosystem studies on environmental issues. Benthic invertebrates, or insects found at the bottom of waterbodies, can be key indicators of stream health and play important roles in nutrient cycling and the food chain. In 1995, a project within the TLW aimed to evaluate how stream ecosystems respond to tree harvesting, which involved long-term surveys of benthic invertebrate communities pre- and post-harvest. Three stream catchments (c31, c33, c34) were harvested at different intensities in the summer of 1997 and were compared to multiple undisturbed catchments. Alongside the invertebrate data, corresponding stream habitat surveys, streamside litterfall traps, leaf decomposition, deposition of stream particulate matter, and standing sediment bedload data was collected during the same period. The data was collected from 1995-2009 by researchers at the Canadian Forest Service (Great Lakes Forestry Centre). This dataset is a rare and valuable resource because there are very few existing long-term datasets of benthic invertebrates from the same locations, and because this dataset is integrated with other biological and chemical datasets within the broader TLW database stored at the Open Government data repository. For an overview of other types of data available from the TLW, see https://doi.org/10.1002/hyp.14109, and for a complete list of publications that have been produced from data collected at this site, see https://www.canada.ca/en/environment-climate-change/services/turkey-lakes-watershed-study/publications.html.