Daniel Hepenstrick


Last Name

Hepenstrick

First Name

Daniel

ORCID

0000-0003-1090-6888

Organisational unit

Filters

2021 - 20223
Reset filters

Search Results

Publications 1 - 3 of 3
  • Factors determining bryophyte species richness and community composition on insular siliceous erratic boulders in calcareous landscapes
    Item type: Journal Article
    Hepenstrick, Daniel; Bergamini, Ariel; Webster, Clare; et al. (2021)
    Journal of Vegetation Science
    Aim: Pleistocene erratic boulders are rocks that were relocated by glaciers during the Ice Ages. When their geology differs from the geology of the landscape that surrounds them, erratic boulders form habitat islands for regionally rare, edaphically specialised, rock-dwelling cryptogams (bryophytes, ferns and lichens). Such boulders constitute terrestrial model systems for exploring island biogeographic predictions and the effect of environmental variables on species diversity and community composition, which we studied in order to provide basic knowledge of the ecology, with relevance for the conservation, of these unusual island systems. Location: Siliceous erratic boulders in the calcareous Swiss Plateau and Jura Mountains. Methods: For 160 erratic boulders we recorded all bryophyte species and a diverse set of environmental variables. For all species and for specialist species (acidophile rock-dwellers) separately, we analysed species–area relationships and nestedness, and explored relationships between environmental variables, species diversity and community composition. Results: We found 138 bryophyte species, 19 of which were specialists of erratic boulders. A steeper species–area curve for boulder specialists than for total species richness underlined the island properties of boulders for specialist species. Large boulders were more likely to harbour numerous boulder specialists and communities on small boulders were nested within the communities present on large boulders. However, at the landscape level small boulders contributed more specialist species than a few large boulders of the same surface area. Erratic boulders near settlements were less likely to harbour boulder specialists. Boulders in open land harboured different and more specialist species than boulders in forests. Conclusions: Large undisturbed erratic boulders in open land harbour rare bryophyte communities with a large number of specialist species. Conservation should thus prioritise this type of boulders. Furthermore, conserving large boulders is logistically easier, and they may function as flagships for small boulders that also contribute to the biodiversity within landscapes.
  • Conservation biology of the flora of erratic boulders
    Item type: Doctoral Thesis
    Hepenstrick, Daniel (2021)
  • Neither connectivity nor genetic diversity matter in the conservation of a rare fern and a moss on insular erratic boulders
    Item type: Journal Article
    Hepenstrick, Daniel; Zemp, Niklaus; Widmer, Alex; et al. (2022)
    Conservation Genetics
    Erratic boulders provide habitat for rock-dwelling species and contribute to the biodiversity of landscapes. In the calcareous Swiss lowlands, siliceous erratic boulders are exclusive habitat islands for the regionally critically endangered fern Asplenium septentrionale, about 20 bryophyte species and numerous lichens. Focusing on island biogeographical processes, we analysed the conservation genomics of A. septentrionale and the moss Hedwigia ciliata on insular erratic boulders in the Swiss lowlands and the adjacent "mainland" in siliceous mountains. We genotyped both species using double digest restriction associated DNA sequencing (ddRAD). For the tetraploid A. septentrionale, abundant identical multilocus genotypes within populations suggested prevalent intragametophytic selfing, and six out of eight boulder populations consisting of a single multilocus genotype each indicated single spore founder events. The genetic structure of A. septentrionale mainland populations coincided with Pleistocene glacial refugia. Four genetic lineages of H. ciliata were identified, and populations consisting of a single multilocus genotype were less common than in A. septentrionale. For both taxa, multilocus genotype diversity on boulders was lower than in mainland populations. The absence of common genetic groups among boulder populations, and the absence of isolation by distance patterns, suggested colonisation of boulders through independent long-distance dispersal events. Successful boulder colonisation of A. septentrionale seems to be rare, while colonisation by H. ciliata appears to be more frequent. We conclude that pivotal principles of conservation biology, such as connectivity and genetic diversity, are of less importance for the studied cryptogams on insular erratic boulders because of long-distance dispersal, intragametophytic selfing and polyploidy.
Publications 1 - 3 of 3