Inferring diversity patterns along an elevation gradient from stacked SDMs: A case study on Mesoamerican ferns

Glaciers are a prominent feature in high mountains and can affect plant distribution along the gradients. However, the possible effect of glaciers on plant community structure at landscape scale has been little studied. We asked: if a glacier tongue crosses a slope laterally and potentially blocks dispersal and migrations, how can this affect vegetation structure and species composition below and above this barrier? A suitable study system is offered by slopes on Mt. Kazbegi, where we established a transect through the subnival and nival belts. We sampled vegetation below and above the glacier tongue and conducted direct gradient analyses to reveal possible effects of the glacier on patterns of species distribution and vegetation structure such as the ratio of solitary plants in vegetation patches. The obtained results indicate that the glacier tongue in our study does not cause a ?vegetation switch? in the usual sense of this phrase. However, it might contribute to an abrupt change in the share of solitary plants, as well as to a very rapid decline of plant abundance and species numbers above the glacier.

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A Small-Scale Analysis of Elevational Species Richness and Beta Diversity Patterns of Arthropods on an Oceanic Island (Terceira, Azores)

Insects ◽

10.3390/insects12100936 ◽

2021 ◽

Vol 12 (10) ◽

pp. 936

Author(s):

Jan Peter Reinier de Vries ◽

Emiel van Loon ◽

Paulo A. V. Borges

Keyword(s):

Species Richness ◽

Introduced Species ◽

Beta Diversity ◽

Climatic Factors ◽

Elevation Gradient ◽

Small Scale ◽

Native Forest ◽

Species Replacement ◽

Diversity Patterns ◽

Total Species Richness

We present an analysis of arthropod diversity patterns in native forest communities along the small elevation gradient (0–1021 m a.s.l.) of Terceira island, Azores (Portugal). We analysed (1) how the alpha diversity of Azorean arthropods responds to increasing elevation and (2) differs between endemic, native non-endemic and introduced (alien) species, and (3) the contributions of species replacement and richness difference to beta diversity. Arthropods were sampled using SLAM traps between 2014 and 2018. We analysed species richness indicators, the Hill series and beta diversity partitioning (species replacement and species richness differences). Selected orders (Araneae, Coleoptera, Hemiptera and Psocoptera) and endemic, native non-endemic and introduced species were analysed separately. Total species richness shows a monotonic decrease with elevation for all species and Coleoptera and Psocoptera, but peaks at mid-high elevation for Araneae and endemic species. Introduced species richness decreases strongly with elevation especially. These patterns are most likely driven by climatic factors but also influenced by human disturbance. Beta diversity is, for most groups, the main component of total (gamma) diversity along the gradient but shows no relation with elevation. It results from a combined effect of richness decrease with elevation and species replacement in groups with many narrow-ranged species.

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