Water Stress Adaptations by Rhododendron arboreum Smith in The Himalayan Treeline Environment: Rhododendron arboreum: Water Stress Adaptations at the Himalayan Treeline

Nandan Singh; Ashish Tewari; Shruti Shah; Amit Mittal

doi:10.15625/2525-2518/19589

Author affiliations

Authors

Nandan Singh Department of Forestry and Environmental Science, Kumaun University, Nainital - 263001, Uttarakhand, India https://orcid.org/0000-0001-6307-8997
Ashish Tewari Department of Forestry and Environmental Science, Kumaun University, Nainital - 263001, Uttarakhand, India
Shruti Shah Department of Forestry and Environmental Science, Kumaun University, Nainital - 263001, Uttarakhand, India
Amit Mittal Graphic Era Hill University, Bhimtal Campus, Nainital - 263126, Uttarakhand, India https://orcid.org/0000-0003-4513-3846

DOI:

https://doi.org/10.15625/2525-2518/19589

Keywords:

Leaf conductance, osmotic potential, R. arboreum, treeline, water potential

Abstract

Drought is amongst the most important climatic events which can severely impact natural ecosystems. The under-canopy Indian Himalayan tree species are less studied on water stress in harsh climatic conditions. Rhododendron arboreum is an ecologically and economically important tree species and distributed between 1500–3500 m asl in the Himalayan ecosystems. In this study, we have tried to assess the water stress adaptations by R. arboreum near the treeline ecotone located at 30°11´02˝N and 79°39´36˝E between 3100 and 3500 m asl elevation. Water potential (Ψ) was measured using a Pressure chamber and leaf conductance with the help of AP₄ porometer. Soil moisture (S_m) across the depths was highly variable (p<0.05). The pre-dawn water potential (Ψ_PD) of R. arboreum tree varied between -0.12 and -0.91 MPa. ANOVA showed that the Ψ_PD of R. arboreum seedlings varied significantly across the years, seasons, and sites (p<0.05). The decline in osmotic potential at full turgor (Ψπ₁₀₀) was -1.18 to -1.20 MPa in trees and -1.42 to -1.72 MPa in seedlings. The morning leaf conductance (gw_AM) of R. arboreum trees ranged from 58.00 to 271.68 m mol m^-2sec^-1. Correlation showed that the maximum leaf conductance in R. arboreum trees was observed when the Ψ_PDwas -0.5 to -0.9 MPa. Water uptake function in plants is generally affected by winter frost which can change the Ψ, osmotic potential, and leaf conductance of plants. The Ψ_PDin the species was relatively high across all seasons in the treeline areas to disrupt physiological activities.

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