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BRYOPHYTE DIVERSITY ACROSS VOLCANIC MICROHABITATS IN THE KHAYBAR WHITE VOLCANO GEOPARK (SAUDI ARABIA)

Authors Vincent Hugonnot^¹, Florine Pépin^¹ & Jan Freedman^²

Published 30 December 2025 Volume 3:2 Pages 209-228

Checked for plagiarism Yes

Peer reviewer comments 2

¹ 25, Impasse des Oponces, 43380 Blassac, France.

² Royal Commission for AlUla, Saudi Arabia

*Correspondence: vincent.hugonnot@wanadoo.fr

Abstract

Bryophytes are generally rare in arid environments, where the availability of suitable microhabitats significantly influences their occurrence. Volcanic landscapes may offer a variety of microsites that moderate extreme climatic conditions; however, bryophyte communities in these environments are poorly documented, particularly in the Arabian Peninsula. This study aimed to investigate bryophyte diversity and the role of volcanic microhabitats in structuring bryophyte assemblages within the volcanic landscapes of the Khaybar White Volcano Geopark in Saudi Arabia. Field surveys were conducted across a large volcanic area using standardized field relevés adapted from bryosociological practices. A total of 450 relevés were conducted at 551 sampling sites distributed across a 5 × 5 km grid, yielding 1,806 floristic records. Twelve bryophyte-bearing microhabitats were identified and characterized. Species presence-absence data were analyzed using Jaccard distances and Non-metric Multidimensional Scaling (NMDS) to explore floristic relationships among microhabitats. Redundancy Analysis (RDA) with forward selection was applied at the relevé level to identify abiotic predictors structuring species composition, including microhabitat slope, substrate depth, and categorical microhabitat descriptors.The results reveal a diverse bryophyte assemblage associated with distinct volcanic microhabitats, including shaded lava fissures, soil pockets, runoff channels, and geothermal fumaroles, the latter supporting several specialized taxa. The RDA explained 33.8% of total inertia, with microhabitat categories accounting for the largest fraction of explained variation. Species distribution patterns indicate that small-scale substrate heterogeneity plays a key role in maintaining bryophyte diversity in this extremely arid environment. These findings highlight the ecological importance of microhabitats created by volcanic substrates and suggest that such microsites may contribute to the persistence of bryophytes in desert landscapes.