Phytodiversity, ecological attributes and phytogeographical distribution of plants in Arang Valley, District Bajaur, a remote area in the Northwest of Pakistan

Abstract

The present study reports the floristic diversity and ecological attributes of 218 plant species belonging to 77 families from the Arang Valley, Bajaur, Pakistan. Of the total species, 187 (85.78%) were dicots, 27 (12.38%) monocots, three (1.37%) pteridophytes and only one (0.46%) gymnosperm. Asteraceae with 24 species (11.01%) was found to be the largest family, followed by Lamiaceae with 18 species (8.26%), Poaceae with 16 species (7.34%), Fabaceae with 15 species (6.88%) and Rosaceae with 11 species (5.05%). The dominant life forms were therophytes (43.58%), hemicryptophytes and nanophanerophytes (13.76%) each, and geophytes (11.93%). Mesophanerophytes (11.01%) and chamaephytes (5.96%) were the least common life forms. The higher number of therophytes, followed by hemicryptophytes and nanophanerophytes, reflects the xeric nature of the vegetation. According to leaf size, the vegetation consisted of microphylls (34.4%), nanophylls (27.98%) and mesophylls (26.16%), with leptophylls (9.63%), megaphylls and macrophylls (0.46%) being the least common. Cuscuta reflexa and Periploca aphylla were the aphyllous species. In terms of habit, the vegetation consisted predominantly of herbs (73.9%), followed by shrubs (13.8%), trees (11.0%), and lianas (1.38%). Based on their life cycle, plants were primarily annuals (49.5%) or perennials (48.6%), while biennials were rare (1.83%). The phytogeographical distribution reveals that the pluri-regional elements of the Irano-Turanian, Sino-Japanese, and Mediterranean regions (29 species, 13.3%) are dominating, followed by the cosmopolitan and Hamalian elements (24 species, 11%). The next dominant bi-regional elements in the area are Irano-Turanian and Sino-Japanese (19 species, 8.72%). Further research is required in order to map the vegetation structure and threatened species that are susceptible to biotic and abiotic stresses.