Structural and functional responses in widespread distribution of some dominant grasses along climatic elevation gradients

Abstract

The adaptability potential of plants enables them to colonize diverse habitats along elevation gradients. Studying these adaptive traits and linking them to environmental attributes provide useful information to understand limitations imposed by elevation gradients on distribution of plant species. To meet these objectives, six most dominant perennial grass species with broad distributional ranges along an elevation gradient from 300–1400 m a.s.l in northern Punjab (Pakistan) were selected for the present study. Dominance of different grass species were linked to proportion of parenchyma, sclerification of aerial plant parts, size of vascular tissue, leaf thickness, and size and density of trichomes. Chrysopogon serrulatus dominated all elevations except the highest one, which was directly linked to increased root area and high proportion of storage parenchyma, vascular region, large metaxylem vessels, increased sclerification in aerial parts, and size and density of trichomes. Cymbopogon jwarancusa dominated lower and middle elevations (300–1000 m) and exhibited increased sclerification in stem and leaves, higher vascular bundle area, and, increased leaf sheath thickness. Lognormal distribution exhibited a non-linear response for eco-morphological and physiological characteristics with decreasing pattern along increase in elevation. Physiological traits responded negatively in response to climatic variables. Root anatomical traits exhibited nonlinear response at lower elevation, while stem traits responded positively at medium elevational gradients (700–1000 m). Leaf sheath showed positive response with elevation and temperature. In conclusion, morpho-physiological and anatomical modifications were specific to grasses studied, which contributed differently towards growth and survival along elevation gradient.