Field study maps 10 plant habitat types on western Mount Hermon, Lebanon

A field study of the Lebanese western slopes of Mount Hermon documented 383 vascular plant taxa and characterized 10 plant-community types across elevations of 1,000–2,500 meters. The researchers also mapped habitats alongside agricultural land, urbanized areas, planted forests and a 12.89-square-kilometer nature reserve. The study was conducted annually from 2020 through 2023, with fieldwork carried out between May and August in the Rachaya district.

Investigators surveyed 169 circular plots of 314 square meters each, recording every vascular plant species and its cover-abundance. Artificial habitats such as urban areas, planted forests and agricultural land were not included in the vegetation sampling. The flora of Syria and Lebanon served as the identification reference, while species nomenclature followed the International Plant Names Index.

The records included 24 taxa endemic to Mount Hermon and Mount Lebanon, two endemic to Mount Hermon and Anti-Lebanon, and one endemic exclusively to Mount Hermon. Fabaceae, Asteraceae, Poaceae, Apiaceae and Lamiaceae together accounted for 56.7% of the identified taxa. The researchers combined the vegetation observations with climatic and terrain variables, using 1981–2010 average annual precipitation and mean annual temperature from CHELSA at 30-arcsecond resolution, alongside slope and aspect derived from one-arcsecond Shuttle Radar Topography Mission data.

Plant-community composition was analyzed with Bray–Curtis dissimilarity, unweighted pair-group clustering with arithmetic mean, and two-dimensional nonmetric multidimensional scaling. Diagnostic species were assessed using percentage frequency, the phi coefficient of association and Fisher’s exact test. Taxa with constancy of at least 25% and p ≤ 0.001 in at least one site group were treated as constant.

Ten groups emerged from the 169 plots: three in the oro-Mediterranean belt above 2,000 meters, three in the supra-Mediterranean belt between 1,000 and 1,600 meters, and four in the montane-Mediterranean belt between 1,600 and 2,000 meters. The three oro-Mediterranean groups consisted of hedgehog-heaths characterized by Astragalus echinus and Noaea mucronata, hedgehog-heaths characterized by Tanacetum densum and Astragalus cruentiflorus, and limestone-cliff vegetation marked by Rosularia sempervivum subsp. libanotica. The supra-Mediterranean groups comprised grasslands with Eryngium glomeratum, upper woodlands containing Quercus infectoria, Q. coccifera and thickets of Crataegus azarolus, and lower evergreen Q. coccifera woodlands.

The four montane-Mediterranean groups were scree deciduous woodlands of Prunus korshinskyi and Lonicera nummulariifolia, montane woodlands of deciduous P. korshinskyi and evergreen Q. coccifera, montane thickets of Astragalus gummifer, and deciduous woodlands of Quercus look and Acer monspessulanum subsp. microphyllum. Nonmetric multidimensional scaling broadly reproduced the cluster results, with a stress value of 0.1541. A one-way analysis of similarities found significant differences in plant-community composition among the groups, with R = 0.80 and p < 0.0001.

Elevation and mean annual temperature had the strongest associations with the ordination axes, with r² values of 0.889 and 0.858, respectively, both at p < 0.001. Slope was also significantly associated with the axes at r² = 0.227 and p < 0.001, as was northness at r² = 0.082 and p < 0.01. Annual precipitation and eastness were not significantly correlated with the ordination.

Each habitat had a distinctive plant assemblage. The hedgehog-heath characterized by A. echinus and N. mucronata occupied slopes and thalwegs with relatively deeper soil and contained 12 endemic taxa, the largest number recorded for any mapped habitat. The montane woodland of Q. look and A. monspessulanum subsp. microphyllum contained 10 endemic taxa, while the scree deciduous woodlands of P. korshinskyi and L. nummulariifolia contained six.

The study proposed five habitat subtypes for Lebanon’s national typology: the two oro-Mediterranean hedgehog-heath types, the oro-Mediterranean limestone-cliff community and two forms of montane deciduous woodland involving P. korshinskyi. Several limitations constrained complete sampling and classification. The remaining Juniperus excelsa population was located and mapped but could not be physically reached.

Closely related habitats with similar floras were represented by unified map polygons, while the composition-based analysis did not effectively distinguish degraded forms of supra-Mediterranean woodlands. The researchers also noted that grazing, wood exploitation, agriculture and fire have shaped the present vegetation, but the study did not quantify these historical effects. The findings provide a habitat-based inventory for a region whose flora remained relatively understudied.

The researchers proposed that the mapping could support management of the nature reserve, which encompasses the majority of the identified habitats. They also described the vulnerability of Q. look woodlands and J. excelsa woodlands in the context of past exploitation and identified a need for protective measures and restoration, while noting that such measures could also support pastoralists seeking shade during hot summer months.

Subject of Research: Field-based characterization and mapping of plant habitats on the western slopes of Mount Hermon in Lebanon

Article Title: Habitat characterization and mapping on the western slopes of Mount Hermon in Lebanon

Article References: El Zein, H., Chalak, L., Baydoun, S., Khater, C., Choueiter, D., & McKenna, M. (2024). Habitat characterization and mapping on the western slopes of Mount Hermon in Lebanon. Vegetation Classification and Survey, 5, 85-107. https://doi.org/10.3897/vcs.106377

Image Credits: AI Generated

DOI: 10.3897/VCS.106377

Keywords: Mount Hermon, Lebanon, habitat mapping, plant communities, vegetation, floristic diversity, endemic plants, Mediterranean ecosystems, biodiversity conservation, Habitat, characterization, mapping