Analysis of floristic composition and species diversity of vascular plants native to the State of Palestine (West Bank and Gaza Strip)

This study aims at providing an updated checklist of the native vascular flora of the Palestinian West Bank and Gaza Strip (State of Palestine, SP), serving as a taxonomic and nomenclatural basis for botanical research and encouraging new floristic surveys and biosystematic studies. The study provides an up-to-date checklist of native vascular taxa of the SP and their distribution within the plant districts in the country. This is the very first annotated checklist for the native vascular plants of the SP which incorporates recent name changes, new distribution records, habitat, herbarium specimens catalouge, Red List criteria, wild edible plants, endemism and use in Traditional Palestinian Herbal Medicine. The quantitative analysis of the flora has shown that the SP hosts 1826 taxa, distributed in 686 genera and 108 families; five taxa are gymnosperms, nine taxa are Pteridophytes and 1812 taxa are angiosperms. The most represented families are Leguminosae (222 taxa, 12.2%), Asteraceae (197, 10.2%) and Poaceae (196, 10.7%), while the most represented genera are Trifolium (38, Leguminosae), Silene (32, Caryophyllaceae), Astragalus (27, Leguminosae), Medicago (26, Leguminosae), Allium (25, Amaryllidaceae) and Euphorbia (25, Euphorbiaceae). Annuals (52.4%), Hemicryptophytes (20.2%) and Chamaephytes (12.2%) are the most represented life-forms amongst the SP flora. The richest plant districts in the SP vascular plant taxa are Gaza Strip (GS) (1216 taxa), Jerusalem and Hebron Mountains (JHM) (1235) and Nablus Mountains (NM) (1126). Agglomerative hierarchical clustering (AHC) permitted the division of SP into two main regions, based on the existence of vascular plant taxa: Region 1 (western plant districts with 1128-1237 taxa) with higher water availability and temperate Mediterranean climate which permit the establishment of more than 65% of the total SP flora in these districts and Region 2 (eastern plant districts with 571-698 taxa), characterised by desert and semi-desert conditions, as well as the presence of alluvial and co-alluvial soils, which allow the survival of lower numbers of plant taxa. One hundred and sixty-five taxa of the SP flora are endemic and near-endemic. However, in comparison with some countries of the Mediterranean Basin, this number is below the average endemism concentration, along with other southern arid countries, such as Tunisia and Egypt. In total, there are 102 threatened plant taxa, belonging to 39 families and 83 genera representing 5.6% of the total plants in the SP. IUCN and the Conservation Measures Partnership (CMP) unified classification of direct threats for SP Red-Listed plants has shown a high extinction risk to the Palestinian threatened wild flora, with 76.5% of the threatened species being either critically endangered (CR) or endangered (EN); only 23.5% were vulnerable (VU). However, several taxa are threatened by numerous factors including small population size, human activities, for example, conversion of traditional to intensive agriculture accompanied by deep ploughing and the application of pesticides, urban development and construction, global climatic change, drying of marshes and wetlands, quarrying, fires and pollution. This checklist can help focus conservation efforts and provide a framework for research, protection and policy applications for the SP flora, especially for the endemic and threatened plants.