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<p>Mountainous ecosystems present complex environmental gradients such as variations in temperature, atmospheric pressure, and precipitation—that play a critical role in shaping plant adaptive responses across elevations. This study examined the altitudinal variations in <i>Dodonaea viscosa</i> across a 300–1500&#xa0;m a.s.l. gradient within the Potohar Plateau, Pakistan, by categorizing populations into lower (300–600&#xa0;m), medium (900&#xa0;m), and higher altitudes (1200–1500&#xa0;m). Results revealed that plants at lower altitudes exhibited significantly greater plant height, shoot length, leaf number, and shoot biomass, suggesting favorable growth conditions characterized by higher temperatures, lower atmospheric pressure, and greater resource availability. In contrast, plants at higher altitudes showed reduced aboveground growth but displayed significantly greater root length and root biomass, indicating an adaptive shift toward belowground resource acquisition in response to lower temperatures and increased environmental stress. Physiologically, proline, soluble sugar, and free amino acid contents were significantly elevated in plants at higher altitudes, highlighting osmoprotective and stress tolerance mechanisms under colder, drier, and high-radiation environments. Conversely, chlorophyll <i>a</i>,<i> b</i>, total chlorophyll, and carotenoid contents were significantly higher in lower altitude populations, suggesting enhanced photosynthetic capacity in less stressful, more optimal conditions. Anatomical analysis revealed that plants at lower altitude possessed greater stem and leaf dimensions, thicker cortical and mesophyll tissues, and larger vascular structures (e.g., vascular bundles, metaxylem), facilitating efficient nutrient and water transport. In contrast, higher altitude populations exhibited smaller stem and leaf dimensions, reduced vascular bundle areas, and decreased stomatal density, reflecting conservative water-use strategies. However, they also showed increased epidermal and sclerenchyma thicknesses, suggesting enhanced structural support under mechanical and environmental stress. Collectively, these findings demonstrate that <i>D. viscosa</i> exhibits altitude-dependent morphological, physiological, and anatomical modifications driven by climate-related stressors. Lower altitudes promote photosynthetic productivity and biomass accumulation, while higher altitudes favor resource conservation and stress tolerance strategies essential for survival under harsher environmental conditions.</p>

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Altitude-Driven Structural and Functional Modifications in Hopbush (Dodonaea viscosa Jacq.) Across the Himalayan Range

  • 期刊论文

  • 发表日期：

    2025年8月6日

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  • Khawar Majeed,
  • Farooq Ahmad,
  • Ummar Iqbal

摘要

Mountainous ecosystems present complex environmental gradients such as variations in temperature, atmospheric pressure, and precipitation—that play a critical role in shaping plant adaptive responses across elevations. This study examined the altitudinal variations in Dodonaea viscosa across a 300–1500 m a.s.l. gradient within the Potohar Plateau, Pakistan, by categorizing populations into lower (300–600 m), medium (900 m), and higher altitudes (1200–1500 m). Results revealed that plants at lower altitudes exhibited significantly greater plant height, shoot length, leaf number, and shoot biomass, suggesting favorable growth conditions characterized by higher temperatures, lower atmospheric pressure, and greater resource availability. In contrast, plants at higher altitudes showed reduced aboveground growth but displayed significantly greater root length and root biomass, indicating an adaptive shift toward belowground resource acquisition in response to lower temperatures and increased environmental stress. Physiologically, proline, soluble sugar, and free amino acid contents were significantly elevated in plants at higher altitudes, highlighting osmoprotective and stress tolerance mechanisms under colder, drier, and high-radiation environments. Conversely, chlorophyll a, b, total chlorophyll, and carotenoid contents were significantly higher in lower altitude populations, suggesting enhanced photosynthetic capacity in less stressful, more optimal conditions. Anatomical analysis revealed that plants at lower altitude possessed greater stem and leaf dimensions, thicker cortical and mesophyll tissues, and larger vascular structures (e.g., vascular bundles, metaxylem), facilitating efficient nutrient and water transport. In contrast, higher altitude populations exhibited smaller stem and leaf dimensions, reduced vascular bundle areas, and decreased stomatal density, reflecting conservative water-use strategies. However, they also showed increased epidermal and sclerenchyma thicknesses, suggesting enhanced structural support under mechanical and environmental stress. Collectively, these findings demonstrate that D. viscosa exhibits altitude-dependent morphological, physiological, and anatomical modifications driven by climate-related stressors. Lower altitudes promote photosynthetic productivity and biomass accumulation, while higher altitudes favor resource conservation and stress tolerance strategies essential for survival under harsher environmental conditions.