Functional Traits of Male and Female Leaves of Hippophae tibetana on the Eastern Edge of the Tibetan Plateau and Their Altitudinal Variability

Abstract

To date, there have been few studies of the functional traits of the dioecious Hippophae tibetana Schlecht leaves, either male or female, in response to ecological factors such as altitude. Elucidating these relationships will establish an important scientific basis for vegetation restoration and reconstruction of the Tibetan Plateau ecosystem. The natural populations of H. tibetana, distributed across three field sites, at 2868 m, 3012 m and 3244 m, in Tianzhu, Gansu, were studied by field survey sampling and laboratory analysis. In particular, the adaptions of leaf functional traits to elevation in these dioecious plants were analyzed. The results show that: (1) there is no “midday depression” of photosynthetic activity in either male or female plants. Over a one-day period, the net photosynthetic rate (Pn) and transpiration rate (Tr) of H. tibetana female plants were higher than those of male plants (p < 0.05). This correlated to the period of vigorous fruit growth in the female plant. The measured Pn and Tr were maximal at the intermediate altitude (3012 m). The light compensation point (LCP) of the leaves of male and female plants were 57.6 and 43.2 μmol·m−2·s−1, respectively, and the light saturation points (LSP) of the leaves were 1857.6 and 1596.8 μmol·m−2·s−1. (2) Altitude had a significant effect on plant and leaf functional traits of male and female H. tibetana (p < 0.05), and no significant difference was noted between plants at the same altitude. The values for leaf area (LA), specific leaf weight (LMA), leaf phosphorus content per unit mass (Pmass) and leaf phosphorus content per unit area (Parea) were also maximal at the intermediate altitude. Leaf nitrogen content per unit area (Narea) and leaf nitrogen content per unit mass (Nmass) increased with altitude. This indicated that the functional traits of male and female plants and leaves of H. tibetana showed a strong “trade-off relationship” with altitude. (3) Pearson correlation analysis showed that there were significant correlations among functional traits of H. tibetana leaves. Redundancy analysis (RDA) showed that soil water content (SWC), altitude (Alt) and soil organic carbon (SOC) had significant effects on the functional traits of H. tibetana leaves (p < 0.05).

The Effects of Long-Term Precipitation Exclusion on Leaf Photosynthetic Traits, Stomatal Conductance, and Water Use Efficiency in Phyllostachys edulis

“…Identifying critical thresholds of drought impact intensity and duration is of high interest for assessing the potential abilities of tree species to adapt to the changing climate in their native environments [2,8,35]. More and more scholars are applying extreme drought stress to observe the responses of leaf physiological characteristics, their potential to recover from the imposed stress, and the desiccation and mortality processes among different populations [35,46,47]. Soil water content is a major environmental factor affecting plant growth, and drought stress often restricts plant growth and development, especially photosynthesis [8,48,49].…”

“…Soil water content is a major environmental factor affecting plant growth, and drought stress often restricts plant growth and development, especially photosynthesis [8,48,49]. The soil's response to drought stress can influence the photosynthetic activity through reduced stomata conductance or by causing damage to the mesophyll cells [35,46,47]. For example, the P max of mango plants (Mangifera indica Linn.)…”

“…Plants' stomatal control of the gaseous exchange between leaves and the bulk atmosphere governs their CO 2 uptake for photosynthesis and transpiration, as well as their productivity and water use efficiency [11,12,14,23,35,[51][52][53]. Recent research has mostly been related to g s and the iWUE on a leaf level, and has revealed plants' inner water consumption mechanisms, providing a scientific basis for supplying plants with reasonable amounts of water [6,[12][13][14]35,47,54]. Plants regulate stomatal conductance to optimize their carbon uptake with respect to water loss [6,14,55].…”

“…Compared with non-stressed conditions, drought stress decreased the g s for all three functional plant groups significantly [54]. Drought-stressed experiments were carried out under diverse environmental conditions for one-year-old seedlings from four to seven European beech (Fagus sylvatica L.) populations, and it was found that the drought stress mainly affected gas exchange, and there were different responses to this water stress among the beech populations [47].…”

Drought stress-induced the formation of heteromorphic leaves of Populus euphratica Oliv: evidence from gene transcriptome

“…Leaves are very important organs of plants because they determine photosynthesis, transpiration and photoreception ( Coble et al., 2017 ; Wang and Jiao, 2020 ). At the community and ecosystem level, leaf traits, such as leaf area, specific leaf area, shape, and growth time, are closely related to ecosystem biomass and function through niche separation or overlap, thus affecting community stability ( Sakschewski et al., 2015 ; Fan et al., 2022 ; Huang et al., 2022 ). As the most important adaptive strategy of plants to the environment, the shape of the leaves is not invariant, but changes with the environment.…”