Understanding Species Diversity, Phenology and Environmental Implications of Different Life Forms in Coniferous Forests: A Case Study from Bhallesa Hills of Pir Panjal Mountain, Western Himalaya, India

We assessed, for the first time, the plant assemblages in coniferous forests of temperate and alpine ecosystems of the Himalayas to understand the diversity of species and their phenological behaviours that lead to different growth forms in the climax forest community. In this study, we selected the coniferous forests of Bhallesa Hills, situated in Pir Panjal Mountain (Jammu and Kashmir) of the Himalayan biodiversity hotspot as a study area and used the quadrat method to document the floristic diversity over four years (2018–2021). The study sites were divided into four sub-sites (Chilli, Kahal, Chanwari, Gandoh), and at each site, 25 replicated plots (each measuring 2500 m2, 50 × 50 m2) were established for repeated surveys and documentation. We then analysed species diversity, lifeforms, phenology and leaf size spectra of coniferous plant communities. We consulted various pieces of literature to understand native and non-native plants. The results showed that the species diversity and species richness, growth forms and phenology varied in the experimental plots. In total, we found 328 plant species belonging to 228 genera and 78 families from different localities of various growth forms. Approximately 68.51% of the plant species were native, and 31.49%of the species were non-native. In angiosperms, dicotyledon species were found to be dominant, with 83.23% of the total plant species, while the family Asteraceae was common, with 38 species. The biological spectrum analysis showed 29% of the species were chamaephytes, followed by 28% as therophytes and 21% as phanerophytes. We observed that plant communities respond differently to the existing environment drivers, with chamaephyte and therophytes being more tightly linked to temperate mixed-coniferous and alpine ecosystems, affected by climates and the availability of substrates for their growth and existence. The leaf size spectra analyses showed nanophyll (42.81%) as the dominant group. Conservation-prioritised species (IUCN, regional most threatened species in India), such as Taxus wallichiana Zucc., Picrorhiza kurroa Royle ex Benth., Trillium govanianum Wall. ex D.Don, Aconitum heterophyllum Wall. ex Royle and Euphorbia obovata Decne were found to be the most endangered plants. The results indicated more indigenous species, but there is a slow process of depletion of wild species, leading to colonisation by exotic alien species. This study indicated forests of the Himalayan regions are degrading at a faster rate, species are showing a shift in phenological behaviour due to anthropogenic factors leading to climate change, and indigenous species need conservation measures.