Assessment of functional trait variation in arid-zone plant families to evaluate indicator species for rehabilitation of degraded landscapes

Abstract

Arid-zone plant species persist under fluctuating environmental conditions through adjustments in structural and functional traits, making them valuable ecological indicators. This study aimed to identify key determinants of ecological dominance among representative taxa from diverse families inhabiting diverse arid habitats of Punjab, Pakistan. Morphological, anatomical, and physiological traits were quantified using standard microscopy and biochemical assays. Comparative analyses were conducted among species of Amaranthaceae (Suaeda fruticosa, Chenopodium album, Chenopodium murale), Tamaricaceae (Tamarix aphylla), Cyperaceae (Cyperus rotundus), and Poaceae (Dichanthium annulatum, Cenchrus ciliaris, Cynodon dactylon, Panicum antidotale) to determine adaptive trait syndromes associated with environmental stress tolerance. Marked interspecific variation reflected contrasting ecological strategies. Amaranthaceae species exhibited pronounced physiological plasticity. Chenopodium murale showed the highest catalase, peroxidase, and superoxide dismutase activities, together with thicker root and stem tissues and enlarged cortical cells, indicating strong osmotic regulation, antioxidant defense, and mechanical support. Chenopodium album displayed greater midrib thickness and phloem area, suggesting enhanced photosynthetic efficiency and assimilate transport, whereas Suaeda fruticosa possessed traits linked to salt exclusion and improved water-use efficiency. Within Poaceae, Panicum antidotale attained maximum shoot length, vascular bundle area, and enzymatic activity, reflecting superior hydraulic conductance and stress resilience, while Cynodon dactylon showed reduced shoot and root growth under elevated Na⁺ soils, indicating ionic stress sensitivity. Tamarix aphylla expressed distinct antioxidant responses under highly alkaline conditions, and Cyperus rotundus developed extensive metaxylem vessels facilitating water transport in semi-arid soils. These adaptations help identify indicator species for saline land restoration and sustainable arid ecosystem management.