Remarks and advice to the study of early arthropod succession near melting glaciers

Figures & data

Figure 1. Foreland of the Forni Glacier, Italy. The length (about 3 km) and the width (see the lateral moraine on the left) of the foreland offers a wide substrate open to the colonization of biocoenosis. Photo: Mauro Gobbi.

Figure 2. The cold-adapted springtail Vertagopus sp. from Forni glacier, Italy. Photo: Barbara Valle.

Figure 3. Nebria soror tresignore (K. Daniel, 1903), a stenoendemic and cold-adapted carabid species of the Orobian glaciers (Central Italian Alps). Photo: Mauro Gobbi.

Figure 4. The wolf spider Pardosa cavannae Simon, 1881, from the Calderone glacier foreland, Italy (Valle et al. 2022a). Photo: Barbara Valle.

Figure 5. The cold-adapted, generalist predator Mitopus glacialis (Heer, 1845) (Opiliones) from the pioneer stages of the Forni glacier foreland (Central Italian Alps). Photo: Mauro Gobbi.

Figure 6. Typical pioneer organisms and a hypothesized early food web, less than ten years old, close to a melting glacier. Energy flow is shown by arrows. Intraguild predation among predators occur but is not shown in the diagram. In the figure, arthropods are represented by the following groups: carabid beetles, spiders, harvestmen, mites, aphids, chironomid midges, and springtails. Illustration by Barbara Valle.

Figure 7. Ice front melting with deposition of supraglacial debris along young glacier foreland. Agola glacier, Dolomites (TN, Italy). Photo: Barbara Valle.

Table 1. Field methods for sampling arthropods in glacier forelands.

Organism and purpose	Sampling technique	Remarks	Reference
Microarthropods (springtails and mites)	Pitfall traps	Detect surface activity density of ground-dwelling organisms	Bråten et al. (2012), Valle et al. (2023)
	Flotation	Detects density also of less mobile soil organisms (e.g., juveniles) in mineral soils (e.g., supraglacial debris, young glacier foreland)	Marshall et al. (1994), Valle et al. (2022a, 2023)
	Extraction of soil samples	Detects density of active soil organisms in different soils	Hågvar, Solhøy, and Mong (2009), Valle et al. (2023)
Ground-dwelling macroarthropods (beetles, spiders, harvestmen)	Pitfall traps	Detect surface activity density of ground-dwelling organisms	Bråten et al. (2012), Gobbi (2020)
	Sampling by hand	Recommended if the aim is to obtain an inventory of species diversity	Andersen and Arneberg (2016), Gobbi et al. (2018)
Active or passive aerial transport of arthropods and organic matter into the study site	Sticky traps	Can be placed on poles at different heights and in different directions. Collect both flying and windblown arthropods as well as organic matter	Gobbi, Isaia, and De Bernardi (2011), Flø and Hågvar (2013)
	Fallout traps	Placed on the ground. Collects fallout of windborne animals and organic matter. Avoids arthropods climbing into them by a high rim	Flø and Hågvar (2013)
	Pitfall traps	Collect both flying and windblown arthropods, as well as organic matter, but catches are random	Gobbi, Isaia, and De Bernardi (2011), Bråten et al. (2012), Flø and Hågvar (2013)
	Malaise traps	Collect flying arthropods	Hodkinson et al. (2001)

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Hågvar, S., T. Solhøy, and C. Mong. 2009. Primary succession of soil mites (Acari) in a Norwegian glacier foreland, with emphasis on Oribatid species. Arctic, Antarctic, and Alpine Research 41: 219–27. doi:10.1657/1938-4246-41.2.219.

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Gobbi, M. 2020. Global warning: Challenges, threats and opportunities for carabid beetles (Coleoptera: Carabidae) in high altitude habitats. Acta Zoologica Academiae Scientiarum Hungaricae 66, no. Suppl.: 5–20. doi:10.17109/AZH.66.Suppl.5.2020.

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Gobbi, M., Á. Barragán, M. Brambilla, E. Moreno, W. Pruna, and P. Moret. 2018. Hand searching versus pitfall trapping: How to assess biodiversity of ground beetles (Coleoptera: Carabidae) in high altitude equatorial Andes? Journal of Insect Conservation 22: 533–43. doi:10.1007/s10841-018-0082-8.

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Flø, D., and S. Hågvar. 2013. Aerial dispersal of invertebrates and mosses close to a receding alpine glacier in southern Norway. Arctic, Antarctic, and Alpine Reseach 45: 481–90. doi:10.1657/1938-4246-45.4.481.

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