Plant leaf morphological and photosynthetic physiological characteristics are key functional traits in the adaptability of plants to heterogeneous environments. Analysis of the correlation between leaf morphological traits and photosynthetic physiological characteristics of salt marsh plants is helpful to deepen our understanding of how salt marsh plants adjust their leaf structure and function to adapt to their environment. However, there have been few studies on the relationship between leaf morphology and photosynthetic physiological characteristics of plants in inland salt marshes under a habitat gradient. A Phragmites australis community was divided into three plots based on differences in the wetland habitat conditions: a remote water area (plot I, 400–550 m from the water margin), a middle water area (plot II, 200–350 m from the water margin) and a near water area (plot III, 0–150 m from the water margin). The relationship between leaf morphological traits and photosynthetic physiological parameters of P. australis in heterogeneous habitats was studied. The results showed that as the habitat conditions changed from plot I to plot III, the soil characteristics, above-ground characteristics of the community and the photosynthetically active radiation changed significantly (P < 0.05). Besides, there was a highly significant positive correlation (P < 0.01) between leaf dry weight (LDW) and net photosynthetic rate (P_n), the effective quantum yield of PSII photochemistry (Y(II), actual photochemical efficiency of PSII) and photochemical quenching (QP); and between leaf area and P_n, Y(II) and QP in the three habitats. Moreover, in plot I, P. australis tended to have small and thick leaves with a low LDW and specific leaf area. In plot III, leaves were large and thin to adapt to the change in habitat conditions. This study provides a scientific theoretical basis for understanding the ecological adaptation strategies of plants in the harsh environment of an inland salt marsh and the conservation and management of wetland plants.

Plant organ biomass allocation and morphological characteristics are important functional traits. The responses of plant root, stem, and leaf traits to heterogeneous habitats in floodplain wetlands are highly important for understanding the ecological adaptation strategies of riparian plants. However, the patterns of these responses remain unclear. In a floodplain wetland in the middle reaches of the Heihe River, we studied the responses of the root, stem, and leaf morphological traits and biomass allocation of Leymus secalinus to varying habitat conditions. We measured these traits in three sample plots, delineated based on distance from the riverbank: plot I (near the riparian zone, 50–150 m from the riverbank), plot II (middle riparian zone, 200–300 m from the riverbank), and plot III (far riparian zone, 350–450 m from the riverbank). The results showed that in plot I, L. secalinus tended to have slender roots and stems and small leaves, with a biomass allocation strategy that maximized the root–shoot ratio (RSR). In plot II, L. secalinus had thick stems and moderate leaf and root patterns, and the RSR values were between those of plot I and plot III. In plot III, L. secalinus had thin and short stems and large leaves; furthermore, among the root morphological structures, plot III had the shortest Rhizome length (RL) and longest Rhizome diameter (RD), and the RSR was the lowest. Moreover, there was a significant correlation between organ biomass and leaf thickness, stem length, RD, and RL in the three habitats (p < 0.05). By balancing the biomass allocation among organs, wetland plants in floodplains balance changes in root, stem, and leaf morphological characteristics to improve their environmental adaptation.

Aims: The functional traits of twigs and leaves are closely related to the ability of plants to cope with heterogeneous environments. The analysis of the characteristics of twigs and leaves and leaf thermal dissipation in riparian plants is of great significance for exploring the light energy allocation and ecological adaptation strategies of plant leaves in heterogeneous habitats. However, there are few studies on the correlation between the twig–leaf characteristics of riparian plants and their heat dissipation in light heterogeneous environments. Methods: In this study, the riparian plant Hippophae rhamnoides in Taohe National Wetland Park was the research object. According to the differences in the canopy light environment of the H. rhamnoides population, three habitat gradients were set: I, the full sight zone; II, the moderate shade zone; and III, the canopy cover zone. We studied the relationship between the twig–leaf characteristics of H. rhamnoides and leaf thermal dissipation in a heterogeneous light environment. Important Findings: The results are as follows: from the full sight zone to the canopy cover zone, the population characteristics and the twig, leaf, and photosynthetic fluorescence physiological characteristics of H. rhamnoides demonstrated significant changes (p < 0.05). In the full sight zone, H. rhamnoides tended to have thick leaves with a smaller SLA on short and thick twigs, and the light energy absorbed by the leaves accounted for a higher proportion of thermal dissipation. In the moderate shade zone, H. rhamnoides tended to grow many thin leaves with high SLA on long and thick twigs, and the proportion of light energy absorbed by the leaves for heat dissipation was lower than that in the full sight zone. In the canopy cover zone, H. rhamnoides tended to grow a few large and thick leaves with a low SLA on slender and long twigs, and the proportion of light energy absorbed by the leaves for heat dissipation was the lowest. There was a significant correlation between the twig–leaf and leaf heat dissipation of H. rhamnoides in the three habitats (p < 0.05). The co-variation of plant branches and leaves and the timely adjustment of thermal dissipation in photoheterogeneous habitats reflect the phenotypic plasticity mechanism and self-protection strategy of riparian plants in adapting to heterogeneous environments.

The correlations between leaf traits of plants with floating leaves and the responses of these traits to changes in water depth can be used to explore the ecological adaptation strategies of aquatic plants. However, few studies have investigated the covariation and correlation of leaf petiole and leaf morphological indices of aquatic plants along natural water depth gradients. Three plots were established along a water depth gradient: plot I (shallow water, with a water depth ranging from 0 to 20 cm), plot II (medium water, with a water depth ranging from 20 to 40 cm), and plot III (deep water, with a water level ranging from 40 to 60 cm). The floating plant Nymphoides peltata (S. G. Gmel.) Kuntze was studied in the Qionghai National Wetland Park, Sichuan Province, China. The results showed that N. peltata had large, thin leaves and short, thin leaf petioles in plot I; the leaf petiole and leaf traits were opposite of those in Plot III. In the three plots, leaf petiole length and leaf petiole diameter were significantly negatively correlated with leaf area, leaf circumference, leaf length, and leaf width (p < 0.05). N. peltata can maintain normal growth, survival, and reproduction in heterogeneous habitats with different water depths by altering its leaf morphological characteristics in a timely manner. This study is helpful for understanding the mechanism of phenotypic plasticity in aquatic plants with floating foliage in heterogeneous environments and provides a scientific basis for the management of aquatic plants in wetlands.