Senckenberg Publications

Paper Bernhard Seifert

back

Bernhard Seifert PDF

suppl.

 

The ecology of Central European non-arboreal ants – 37 years of a broad-spectrum analysis under permanent taxonomic control


Abstract

– Methods: A broad spectrum analysis on ant ecology was carried out in Central Europe in 1979–2015, including 232 study plots from 5 to 2382 meters a.s.l. Basically each type of terrestrial, non-arboreal ant habitat was investigated. The full gradient for nearly each environmental variable was covered. The whole study was under permanent taxonomic control, assisted by holding a curated museum collection with updating of the data regarding newly discovered cryptic species. Ant biodiversity and abundance recording was based on direct localization of altogether 17,000 nest sites with nest density determination per unit area. Two new biomass and species richness calculation methods are introduced. Recorded niche dimensions included 6 physico-chemical, 7 structural and 4 species-defined factors. The paper represents the first ecological study with a thorough application of the soil temperature determination system CalibSoil which provides comparability of data on thermal behavior of hypo- and epigaean organisms within the context of global warming. It is shown that approximations of fundamental niche space and niche overlap are possible from field data based on 3 factors: (a) temporal disclosure of hidden fundamental niche space during dynamic processes, (b) mathematic decoupling of fundamental niche space from particular study plot situations by subdivision of niche dimensions into classes and (c) idealization of niche space by smoothing of frequency distributions for all niche variables. A method to estimate interspecific competitive exclusion based on a model that relates realized niche overlap to fundamental niche overlap is provided.
– Results: Thanks to the broad environmental gradients considered and the high number of data points, highly significant relations of species richness and biomass of ant assemblages to nearly each investigated environmental variable could be shown with curve characteristics mostly resembling skewed or unskewed optimum curves whereas quasi-linear relations were rare. The most important directly niche-segregating factors are soil moisture and maximum and mean soil temperature whereas herb-layer phytodensity, ranking at the penultimate place among the assessed environmental variables, is thought to have strong indirect effect by altering moisture and temperature conditions. The distribution of 86 ant species relative to environmental variables is shown. 27 habitat categories were compared for species richness and biomass. Xerothermous to mesoxerophytic grasslands on limestone showed the highest average species richness and biomass of open land habitats with 13.1 species / 100 m² and 8.8 g fresh weight / m². Xerothermous to tempered Quercus wood (12.5 species / 100 m², 5.5 g fresh weight / m²) and mature Fagus woods (0.35 species / 100 m², 0.07 g fresh weight / m²) showed the richest and poorest ant assemblages within woodland habitats. Convincing evidence was presented for E. Odum’s theory that narrow niche spaces increase the number of species a habitat may hold. Species richness and evenness of ant assemblages showed a clearly positive correlation. Gause‘s Law is demonstrated to be valid on the biocenotic level: interspecific competitive displacement increases with growing relatedness – 20 pairs of sibling species had significantly lower coexistence values than 214 congeneric pairs of all other species from the genera to which the sibling species belonged (ANOVA F1,232 = 9.98, p < 0.002). It is shown that predictions of zoogeographic shifts due to global warming based on only meteorological simulations will remain inaccurate because 22–31% of variance of mean seasonal soil temperature TMEAN was attributable to the habitat-specific factors stratification and density of phytolayers, orography (aspect) and properties of ground material.

Keywords

ant biomass | ant species richness | realized and fundamental niche | sibling species | Gause’s Law, calibrated soil temperature | global warming | range prediction | nature conservation


back

https://die-welt-baut-ihr-museum.de/en