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Co-occurrence frequency in vegetation patches decreases towards the harsh edge along an arid volcanic elevational gradient

Title data

Eibes, Pia M. ; Eisenbacher, Judith ; Beierkuhnlein, Carl ; Chiarucci, Alessandro ; Field, Richard ; Jentsch, Anke ; Köhler, Tina ; Vetaas, Ole R. ; Irl, Severin D. H.:
Co-occurrence frequency in vegetation patches decreases towards the harsh edge along an arid volcanic elevational gradient.
In: Frontiers of Biogeography. (2021) . - 24 S..
ISSN 1948-6596
DOI: https://doi.org/10.21425/F5FBG49743

Abstract in another language

Positive plant–plant interactions are thought to drive vegetation patterns in harsh environments,such as semi-arid areas. According to the stress-gradient hypothesis (SGH), the role of positive interactions between species (facilitation) is expected to increase with harshness, predicting associated variation in species composition along environmental gradients. However, the relation between stress and facilitation along environmental gradients is debated. Furthermore, differentiating facilitative interactions from other underlying mechanisms, such as microtopographic heterogeneity, is nottrivial. We analysed the spatial co-occurrence relationships of vascular plant species that form patchy vegetation in arid lapilli fields (tephra) from recent volcanic eruptions on La Palma, Canary Islands. Assuming a harshness gradient negatively correlated with elevation because the lower elevations are more arid and water availability is consideredthe most limiting resource, and that an outcome of facilitation is plants co-occurring in the same patch, from the SGH we expected a greater degree of co-occurrence at lower elevation. We tested this at both the species and the individual plant level. We analysed the species composition of 1277 shrubby vegetation patches at 64 different sampling points, ranging from the coast to around 700 m a.s.l. Patch morphology and microtopographic heterogeneity variables were also measured, to account for their potential effects on the species composition of patches. We used generalized linear models and generalized mixed-effects models to analyse species richness, number of individuals in patches and percentage of patches with positive co-occurrences, and a pairwise co-occurrence analysis combined with a graphical network analysis to reveal positive links between 13 of the species. We found that the percentage of patches with positive co-occurrences increased at higher elevations, in contrast to the predictions of the SGH, but in accordance with a refined stress-gradient hypothesis for arid sites, in which characteristics of the interacting species are incorporated.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Aridity gradient; Canary Islands; Elevational gradient; Facilitation; La Palma; Oceanic island; Plant–plant interactions; Species co-occurrence; Stress-gradient hypothesis; Volcanic substrate
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Biogeography
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Biogeography > Chair Biogeography - Univ.-Prof. Dr. Carl Beierkuhnlein
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professor Disturbance Ecology
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Professor Disturbance Ecology > Professor Disturbance Ecology - Univ.-Prof. Dr. Anke Jentsch
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 550 Earth sciences, geology
500 Science > 580 Plants (Botany)
500 Science > 590 Animals (Zoology)
Date Deposited: 05 Mar 2021 06:48
Last Modified: 05 Mar 2021 06:48
URI: https://eref.uni-bayreuth.de/id/eprint/63710