Ecology of active rock glaciers and surrounding landforms: climate, soil, plants and arthropods

Abstract

Active rock glaciers are periglacial landforms consisting of coarse debris with interstitial ice or ice-core. Recent studies showed that such landforms are able to support plant and arthropod life and could act as warm-stage refugia for cold-adapted species due to their microclimate features and thermal inertia. However, integrated research comparing active rock glaciers with surrounding landforms to outline their ecological peculiarities is still scarce. We analysed the abiotic (ground surface temperature and humidity, soil physical and chemical parameters) and biotic (plant and arthropod communities) features of two Alpine active rock glaciers with contrasting lithology (silicate and carbonate), and compared them with the surrounding iceless landforms as reference sites (stable slopes and active scree slopes). Our data show remarkable differences between stable slopes and unstable landforms as a whole, while few differences occur between active scree slopes and active rock glaciers: such landforms show similar soil features but different ground surface temperatures (lower on active rock glaciers) and different occurrence of cold-adapted species (more frequent/abundant on active rock glaciers). Both plant and arthropod species distributions depend mainly on the geographical context as a function of soil pH and on the contrast between stable slopes and unstable landforms as a function of the coarse debris fraction and organic matter content, while the few differences between active scree slopes and active rock glaciers can probably be attributed to microclimate. The role of active rock glaciers as potential warm-stage refugia for cold-adapted species is supported by our data; however, at least in the European Alps, their role in this may be less important than that of debris-covered glaciers, which are able to host cold-adapted species even below the climatic tree line.

Rock glaciers and related cold rocky landforms: overlooked climate refugia for mountain biodiversity

“…Today, we see continuing evidence of this pattern with elevationally or latitudinally disjunct populations of some species in CRL-linked habitats (Růžička & Zacharada 1994;Fickert et al 2007). Thus, evidence from both the past and present strengthens our prediction that CRLs will sustain long-lasting cold refugia under contemporary climate change (Caccianiga et al 2011;Gobbi et al 2014;Millar et al 2015;Tampucci et al 2017).…”

“…Arthropods are also common on and within CRLs (Table S1). Similar to plants, many arthropod species occur at lower elevations on CRLs than their typical distributions (e.g., Tampucci et al 2017). CRLs can even harbor endemic arthropods.…”

Glacial Biodiversity: Lessons from Ground-dwelling and Aquatic Insects

“…A refuge can be defined as sites able to preserve suitable climate conditions for cold-adapted species in spite of the climate warming [68]. The role of active rock glaciers and debris-covered glaciers as potential warmstage refugia for cold-adapted ground beetle species is supported by data collected on the Italian Alps [16,28,40]. The thermal profile observed on some alpine active rock glaciers supports this view indicating decoupling of the local topoclimate from the regional climate, a key factor for a site to serve as a refugium.…”

“…Even though ground beetle communities of active rock glaciers show few differences in terms of species richness and abundance with respect to scree slopes, some characteristic species of each of the two landforms can be identified. The ground beetle community observed on the rock glaciers is exclusive of this landform because it is composed of large populations of species belonging to the genera Oreonebria, Nebria and Trechus [16,40]. To these genera belong species (e.g., Nebria germari, Oreonebria soror and Trechus tristiculus) typical of cold and wet highaltitude environments.…”

Überraschende Erstnachweise und neue Daten zu seltenen Spinnenarten (Arachnida: Araneae) aus Blockhalden in Baden-Württemberg

“…), besonders in sogenannten Ruhschutthalden, die Art besiedelt von dort aber auch (gesteinsreiche) Grasheiden und strahlt über Geröllhalden und Schuttströme in den Bereich der Waldgrenze (bis auf 1200 m, Thaler 1984, Rief et al 2001. Nach Tampucci et al (2017) tritt P. nigra auch in den italienischen Alpen sowohl in Silikat-als auch in Karbonatsubstraten auf. Von Thaler & Buchar (1996) als Endemit des alpinen Gebirgssystems bezeichnet, ist die Art in Mitteleuropa aus den Südlichen wie Nördlichen Kalkalpen (Österreich, Schweiz, Frankreich, Italien), den Karpaten (Polen, Ungarn) und dem Pirin-Gebirge in Bulgarien bekannt.…”