Identification of functional traits responsible for environmental vulnerability of Cedrus deodara in temperate forests of Western Himalaya

Abstract

Climate change is impacting forest tree species adversely and making the ecological system vulnerable. The present study attempts to assess the internal vulnerability of Cedrus deodara occurring in nine sub-types of temperate forests in Western Himalaya, India via a plant functional trait-based approach. Internal vulnerability was assessed based on sensitivity and adaptive capacity through proposing an index using IPCC framework. Sensitivity was determined based on various traits (indicators) of light harvesting, carbon assimilation, nutrient content, and water budget, whereas adaptability was defined based on light harvesting efficiency, water use efficiency, resource use efficiency, and nutrient limitation. Sensitivity was maximum in Dry Deodar Forest (0.51) and Low-Level Blue Pine Forest (0.51) and minimum in Western Mixed Coniferous Forest (o.38), however adaptability was maximum in Kharsu Oak Forest (0.65) and Moist Deodar Forest-II (0.65) with minimum adaptability for Ban Oak Forest (0.53). In Ban Oak Forest, Low-Level Blue Pine Forest and Moist Deodar Forest-II high stomatal conductance compensates the low chlorophyll achieving homeostasis state for photosynthesis. Negative minimum temperature (-6.95 to −2.04 °C) in winters followed by high monsoon rainfall (417.74 to 1256.13 mm) causes high sensitivity amongst the C. deodara population in Low Level Blue Pine Forest, Dry Deodar Forest and Moist Deodar Forest-II; and adaptability was majorly affected by water availability i.e., excessive monsoon rainfall in Ban Oak Forest (1962.45 mm) and least rainfall in Neoza Pine Forest (349.50 mm). Overall, the vulnerability was high in Low Level Blue Pine Forest (0.46), Ban Oak Forest (0.45) and Dry Deodar Forest (0.45). Present study identified key traits for species vulnerability therefore management intervention should orient towards those silvicultural operations which may reduce relative water use of the species and may also facilitate for improved photosynthesis i.e., through water provision and density management of the C. deodara dominated forests in Himalayan region. The study concludes that a unified approach for managing species of the forest may be disadvantageous and detrimental to forest conservation. Rather site-specific management approach, which led to incremental response to the identified traits may support the conservation of species.