Patterns of spatial autocorrelation in the distribution and diversity of carabid beetles and spiders along Alpine glacier forelands

Marano

et al. 2017

Boreas

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.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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

Tampucci

Marano

et al. 2017

Boreas

“…We adopted a mixed modelling approach for all analyses by fitting Generalized Linear Mixed Models (GLMMs) using the glmer function of the 'lme4' package in R (Bates, Maechler, Bolker, & Walker, ). Study area was specified as a random effect to account for non‐independence of sampling sites from the same location and study (Dormann et al, ; Gobbi & Brambilla, ). In an initial exploratory analysis, we modelled species richness in relation to elevation using the above model structure and specifying a Poisson distribution.…”

Section: Methodsmentioning

confidence: 99%

Trait‐modulated decline of carabid beetle occurrence along elevational gradients across the European Alps

Chamberlain

Journal of Biogeography

Negro

et al. 2020

Aim: To assess how species traits modulate the responses of carabids to elevational gradients, and how consistent these relationships are across different Alpine regions.Location: Italian Alps. Taxon: Coleoptera, Carabidae (ground beetles).Methods: Carabid communities were sampled using pitfall traps along elevational gradients (697-2,840 m) in 416 study sites comprising a range of habitat types. The probability of carabid occurrence was modelled in relation to elevation and its interaction with two key traits, body size and wing development, using a mixed-modelling framework. The consistency of these associations was then assessed across three geographically separated regions. Results:Carabid occurrence declined with increasing elevation, although this relationship was modulated by both body size and wing development. Smaller species were less likely to occur than larger-bodied species at lower elevations. There was a steep decline in occurrence of larger species from low to high elevation, but a slight increase in smaller species, when considering all regions combined. All wing development types declined with elevation, most notably for brachypterous (reduced wings) species. However, these patterns also varied regionally, especially for wing development, indicating that trait-elevation interactions are not geographically consistent.Habitat could not explain the differences between regions for body size, but was likely an important driver of regional differences in the role of wing development on carabid occurrence. Main conclusions:Species traits are important in explaining the distribution of carabids along elevational gradients in mountains, and they may help to identify the species that are the most vulnerable, and the most resilient, to future environmental change. Increased probability of occurrence of smaller species at higher elevations suggests that they may be particularly vulnerable to environmental change in the future. However, the difference in responses to elevation between regions has important implications for modelling species distributions, as it suggests low model transferability, that is, a trait-based model derived from one region cannot necessarily be used to project relative elevational shifts in a wider area. | 1031 CHAMBERLAIN Et AL.

“…Given that our data have a clear spatial structure, with three traps within each sampling plot, and that spatial autocorrelation is a key issue for studies investigating invertebrate ecology (and carabids and beetles in particular) along glacier forelands (Gobbi & Brambilla, ), we adopted a modelling technique able to deal with spatially autocorrelated data. We worked with generalised least squares (GLS) models, which can incorporate the spatial structure into the model's error and are one of the best performing methods for similar spatial analyses (Dormann et al ., ; Beale et al ., ).…”

Section: Methodsmentioning

confidence: 99%

Life in harsh environments: carabid and spider trait types and functional diversity on a debris‐covered glacier and along its foreland

Ballarin

Brambilla

et al. 2017

Ecological Entomology

1. Patterns of species richness and species assemblage composition of ground‐dwelling arthropods in primary successions along glacier forelands are traditionally described using a taxonomic approach. On the other hand, the functional trait approach could ensure a better characterisation of their colonisation strategies in these types of habitat. 2. The functional trait approach was applied to investigate patterns of functional diversity and life‐history traits of ground beetles and spiders on an alpine debris‐covered glacier and along its forefield in order to describe their colonisation strategies. 3. Ground beetles and spiders were sampled at different successional stages, representing five stages of deglaciation. 4. The results show that the studied glacier hosts ground beetle and spider assemblages that are mainly characterised by the following traits: walking colonisers, ground hunters and small‐sized species. These traits are typical of species living in cold, wet, and gravelly habitats. The diversity of functional traits in spiders increased along the succession, and in both carabids and spiders, life‐history traits follow the ‘addition and persistence model’. Accordingly, there is no turnover but there is an addition of new traits and a variation in their proportion within each species assemblage along the succession. The distribution of ground beetles and spiders along the glacier foreland and on the glacier seems to be driven by dispersal ability and foraging strategy. 5. The proposed functional approach improves knowledge of the adaptive strategies of ground‐dwelling arthropods colonising glacier surfaces and recently deglaciated terrains, which represent landforms quickly changing due to global warming.