Plant diversity significantly influences the structure and function of ecosystems and plays a crucial role in soil organic carbon (SOC) sequestration. Research on the relationship between plant diversity and soil organic carbon density (SOCD) can help elucidate the mechanisms of carbon source and sink dynamics in inland salt marshes. In the inland salt marsh wetland of Sugan Lake, three plots (I, II, and III) were established perpendicular to the lake shore based on the historical water level fluctuations. Using community surveys and redundancy analysis, in this study, the patterns of plant community species diversity and SOCD across different habitats were investigated, as were the relationships between them. The results indicated that as the duration of surface water accumulation decreases, the vegetation in the inland salt marsh wetland tends to shift from annual true halophytes (I) to perennial salt-excreting plants (II) and perennial grasses (III). The Shannon‒Wiener index and Pielou index tend to increase, whereas the Simpson index decreases. SOCD also tends to increase. SOCD is significantly positively correlated with the Shannon‒Wiener index and Pielou index and significantly negatively correlated with the Simpson index (P < 0.01). The main factors influencing plant diversity and SOCD are soil water content, soil pH, and underground biomass. Habitat filtering and environmental stressors alter plant functional groups and community species diversity. With the reduction in surface water accumulation duration, the SOC and SOCD increase in inland salt marsh wetlands, reflecting the mechanisms through which plant community composition and species diversity promote SOCD.

Understanding the variations in twig and leaf morphologies and photosynthetic physiological characteristics of riparian forest plants in heterogeneous habitats is of great significance for revealing their phenotypic plasticity mechanisms and ecological adaptation strategies. In this study, the riparian forest plant Periploca sepium Bunge was selected as the research object. According to the canopy light environment experienced by the P. sepium population, three habitats were established: under-canopy, gap, and full-sun areas. We studied the twig and leaf morphological and photosynthetic characteristics of P. sepium under heterogeneous light environments, as well as the relationships between these two aspects. Plants in the under-canopy area developed long and thick twigs with few large leaves, coupled with high actual photosynthetic efficiency of photosystem II (Y(II)) and low non-photochemical quenching (NPQ), whereas those in the full-sun area exhibited the opposite covariation strategy. Significant correlations between twig and leaf morphologies and photosynthetic physiological characteristics were found across all habitats. The coordinated variations in twig and leaf morphologies and photosynthetic physiology of P. sepium embody a resource investment trade-off strategy that plants have evolved through long-term adaptation to heterogeneous light environments.

To clarify the adaptive strategies of invasive plants in heterogeneous lakeside habitats, this study investigated the coordinated responses of biomass allocation and stem-leaf traits of Ageratina adenophora along an environmental gradient in Qionghai Lake’s lakeside zone. According to differences in habitat conditions, the A. adenophora community was divided into three plots: near the shore area (plot I: 50 150 m from the shore, a groundwater depth of 0.30–0.50 m), middle shore area (plot II: 200 300 m from the shore, a groundwater depth of 0.50–0.75 m), and remote shore area (plot III: 350 450 m from the shore, a groundwater depth of 0.75–1 m). Using linear mixed-effects models, multiple stepwise regression, and Mantel tests, we analyzed trait variations and their environmental drivers. The results revealed that along the gradient from near shore to remote shore, A. adenophora shifted from prioritizing aboveground to underground allocation, with root-shoot ratio (RSR) exhibiting the highest plasticity. Stem-leaf traits transitioned from resource-conserving (thin long stems, small leaves) to resource-acquiring (thin short stems, large leaves with high SLA) characteristics. Soil available potassium (SAK) and pH were dominant drivers, with SAK promoting growth-related traits and pH exerting inhibitory effects. Mantel tests confirmed a significant overall association between trait and environmental matrices (r = 0.495, p = 0.001). In heterogeneous habitats, invasive plants in the lakeside zone achieve coevolution of stem and leaf morphological components by balancing the allocation of root and shoot biomass and increasing the success rate of their colonization. This reflects the strong morphological plasticity mechanism and biomass allocation strategy of invasive plants in the lakeside zone. This study reveals that A. adenophora achieves successful colonization via coordinated trait plasticity mediated by key soil factors, providing a scientific basis for targeted management of invasive plants in lakeside zones.

Root exudates serve as a critical pathway for rhizosphere carbon input, yet their response to salinity gradients in inland salt marshes remains unclear. This study investigated Triglochin maritimum across low, moderate, and high salinity zones in the Qinwangchuan salt marsh. We measured root functional traits, root dehydrogenase activity, and root exudation carbon flux to reveal their responses to soil salinity. Results showed that decreasing salinity significantly increased plant height, fine root biomass, specific root length, root dehydrogenase activity, and root exudation rates. root dehydrogenase activity was strongly positively correlated with soil water content (p≤0.01). Exudation rates were closely related to specific root length (p≤0.01), and root exudation carbon flux was significantly positively correlated with fine root biomass (p≤0.01). The water-salinity dynamics in inland salt marsh wetlands influence root architecture, regulate root dehydrogenase activity, and alter root exudation rates and exudate carbon flux. With increasing salinity, salt marsh wetlands exhibit a tendency toward weakened carbon sink function.

Water use efficiency (WUE) is a key index to predict the impact of climate change on ecosystem carbon and water cycles; the tradeoff of stem and leaf traits determine the WUE and resource competitiveness of individual plants. Four altitudinal gradients of 3400 m, 3500 m, 3600 m, and 3700 m were selected as experimental sites in Gahai Wetland on the Ruoerge Plateau. The Mantel Test method and the standardized major axis estimation (SMA) method were employed to examine the relationship between stem-leaf tradeoff and WUE of Kobresia tibetica in alpine peat swamps at different elevations. The results showed that with the increase of altitude, the surface water area decreased gradually, and the height and fractional vegetation cover of wetland community, stomatal conductance (Gs), and transpiration rate (Tr) of Kobresia tibetica showed a decreasing trend (P < 0.05).WUE, photosynthetically active radiation (PAR), vapor pressure deficit (VPD), and the height, fractional vegetation cover, and root-shoot ratio of Kobresia tibetica showed an increasing trend (P < 0.05). The leaf area (LA), leaf thickness (LT), specific leaf area (SLA), stem length (SL), and WUE of Kobresia Tibetica showed different correlations at different elevations. With the increase of altitude, the tradeoff between stems and leaves of Kobresia tibetica changed from stems to leaves, the tradeoff between LA and LT changed from favoring LA to LT, stem and leaf configuration changed from long stem-large LA to short stem-small LA, the net photosynthetic rate (Pn) and WUE increased, and the structural cost and photosynthetic efficiency return of Kobresia tibetica leaves changed from 'high-input-slow return' to 'low-input-fast return'. It reflects the ecological strategy of synergistic adaptation between stem and leaf morphology and photosynthetic characteristics of plants in alpine peat swamp in a heterogeneous habitat.

Biomass allocation patterns affect plant functions across all levels, ranging from plant growth and reproduction to the quality and energy flow of entire communities. Revealing the biomass allocation and allometric growth relationships among the dominant plant formations in alpine peat swamp wetlands not only can help elucidate the life history strategies of swamp plants, but also plays a crucial role in understanding the uncertainty of plant carbon sinks in peat swamp wetlands. Based on community surveys, this study employed analysis of variance (ANOVA) and standardized major axis estimation (SMA) to analyze the species composition, biomass allocation of different organs, and allometric growth relationships of the dominant plant formation in the alpine peat swamp wetlands of the Yellow River on the Gannon Plateau, Gansu Province, China. The results showed the following: (1) Peat swamp plants can be classified into six formations dominated by Carex muliensis, Blysmus sinocompressus, Carex atrofusca, Kobresia tibetica, Kobresia kansuensis, and Carex kansuensis. Environmental filtering was identified as the primary factor influencing the distribution of formations in this region. (2) The biomass allocation ratios of the dominant plant formations were ordered as follows: root mass ratio > leaf mass ratio > stem mass ratio. There were also significant differences in the biomass allocation of roots, stems, and leaves among different plant formations. (3) Isometric growth was observed between the leaf and stem biomass of the dominant plant formations (p > 0.05), while allometric growth relationships existed between root/leaf biomass and root/stem biomass (p < 0.05), with the growth rate of root biomass (RB) being higher than that of leaf biomass (LB) and stem biomass (SB). The biomass allocation patterns and allometric growth relationships among the roots, stems, and leaves of the dominant plant formations in peat swamp wetlands reflect the environmental plasticity mechanism of functional plant traits in heterogeneous habitats. Moreover, combining optimal allocation theory and allometric growth theory can better explain the biomass variation and adaptation mechanisms of dominant plant formations in peat swamp wetlands, providing a theoretical basis for understanding the habitat adaptation patterns of plants in alpine peat swamp wetlands.

Investigating biomass allocation-root trait correlations in lakeside invasive plants enhances understanding of their phenotypic plasticity and resource strategies. Currently, limited research has focused on the linkage between biomass allocation patterns and root morphological characteristics in lakeside invasive species under varying environmental conditions. We examined Ageratina adenophora across three lakeside habitats: near shore area (plot I: 50 150 m from the shore), middle shore area (plot II: 200 300 m from the shore), remote shore area (plot III: 350 450 m from the shore). The correlation between the biomass allocation and root traits of A. adenophora under different habitats was studied. The results revealed that in the near shore area, A. adenophora population exhibited smaller root-shoot ratio accompanied by higher specific root length, branching density and fractal dimension. Conversely, in the remote shore area, A. adenophora counterparts developed larger root-shoot ratio with reduced root length, lower branching density, and simplified fractal dimension. Moreover, there was a significant negative correlation between root traits and stem biomass allocation in three habitats (P < 0.05). These results suggest that A. adenophora employs adaptive biomass allocation strategies to develop differentiated root architecture in heterogeneous lakeside environments, reflecting high phenotypic plasticity that enhances its colonization success through optimized resource acquisition and storage trade-offs. Our findings elucidate how heterogeneous habitats drive belowground trait differentiation in invasive species, providing mechanistic insights into their colonization success.

Research on the coupling effect between soil and plants, as well as its impact on soil organic carbon (SOC) components, is instrumental in elucidating the mechanisms that maintain the stability of carbon pools in inland salt marsh wetlands. In the inland salt marsh wetland of Sugan Lake, three waterlogging gradient plots (I, II and III) were established sequentially from the lake shore, aligned perpendicularly to the shoreline based on historical water level data. Utilizing community investigations and structural equation modeling, this study examined the spatial distribution of SOC components and the stability of the carbon pool across varying waterlogging gradients. As waterlogging duration decreased, recalcitrant (ROC) and labile organic carbon (LOC) increased horizontally in each soil layer, with vertical differences. LOC correlated positively with underground biomass, clay, total dissolved solids, and total nitrogen (P < 0.01); ROC correlated with clay and salinity (P < 0.01). Soil properties were the primary direct driver of carbon stability (0.214), while plant characteristics directly (0.145) and indirectly (0.523) enhanced stability via soil properties. Eco-hydrological processes influence soil physicochemical properties and plant community structure in inland salt marshes. They alter the spatial distribution and mass fraction of SOC components, thereby affecting the carbon pool stability in these wetland ecosystems. This understanding can serve as a reference for the precise assessment of SOC in wetland ecosystems and for the management of soil carbon pools.

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.

Wetland vegetation is the material basis for the formation and development of alpine peatlands. Investigating the relationship between species diversity of plant communities and soil organic carbon (SOC) helps understanding carbon pool source-sink dynamics in alpine peatlands. This study conducted in Zoige Plateau alpine peatlands employed the community survey method to explore changes in species diversity of plant communities and SOC across different habitats and their relationship. Results indicated that from the peatland center to the edge, alpine peatland community types underwent succession as follows: Carex atrofusca community, Carex muliensis + Equisetum fluviatile community, Blysmus sinocompressus + Carex muliensis community, Kobresia kansuensis + Blysmus sinocompressus community, and Kobresia tibetica + Deschampsia cespitosa community. The SOC, water level, soil water content, and biomass of Cyperaceae plants decreased, while community coverage, density, and soil available nitrogen increased. The Shannon–Wiener index and Pielou index increased, while Simpson index decreased. The water level, soil water content, and soil available nitrogen were the main factors influencing the spatial distribution patterns of plant communities. The community density, coverage, biomass of Cyperaceae plants, and water level were the main factors influencing species diversity of plant communities. SOC was highly significantly positively correlated with Simpson index, and negatively correlated with Shannon–Wiener index and Pielou index (p ≤ 0.01). As water level dropped and waterlogged extent diminished, grass hummock microtopography transitioned from spotted to ridged and then to massed. Habitat filtering and environmental stress caused dominant species succession and species diversity of plant communities to change, resulting in SOC content and the quality of carbon pool to decrease in alpine peatlands.

Material input and output are key factors determining the formation and accumulation of soil organic carbon (SOC) in alpine peatlands. The impact of erosion gullies drainage caused by thaw slump on SOC remains unclear. Investigating the SOC spatial differentiation pattern from perspectives of vegetation and hydrothermal conditions can help understand carbon sequestration mechanisms under climate change. This study conducted experiments in drainage alpine peatlands on Zoige Plateau. From undisturbed peatland to the edge of erosion gully, based on water level changes. Four drainage gradient sample plots were designated as follows: undrained (I), lightly drained (II), moderately drained (III), and heavily drained (IV), the effects of community characteristics and soil factors on SOC content at different drainage gradients were studied. Results showed that: Horizontally, the dominant species succession from Carex muliensis (I) to Blysmus sinocompressus (II, III) and Kobresia tibetica (IV), the SOC, soil water content (SWC), C/N, community total biomass (TB), litter count (LC), and root/shoot (R/S) decreased, the soil bulk density (BD), pH, and temperature (ST) increased. Vertically, the SOC in Sample plot I decreased, in Sample plot II, III, and IV initially decreased and then increased. SOC was highly significantly positively correlated with TB, LC, and R/S (p ≤ 0.01). Path analysis indicated that the order of soil factors affecting SOC was SWC > C/N > ST > BD. This study found that drainage influenced hydrological environment of peatlands, community succession altered quantity and quality of material input. These factors disrupted peat accumulation and decomposition balance, changing SOC horizontal and vertical patterns, causing alpine peatlands degradation.

Background and aimsSlope aspect affects the redistribution of solar radiation and precipitation, altering habitat conditions such as temperature, water availability, and soil nutrient composition. However, the impact of slope-induced environmental changes on the synergistic relationship between plant photosynthetic characteristics and leaf functional traits remains underexplored.MethodsFour plots of Cotoneaster multiflorus (C. multiflorus) were established on the southern, eastern, western, and northern slopes within the Xinglong Mountain National Nature Reserve. This study investigated variations in leaf functional traits, photosynthetic-fluorescence characteristics, and environmental responses in C. multiflorus across different slope aspects by mathematical statistics.ResultsOur study revealed that the southern slope demonstrated maxima in transpiration rate (Tr), coefficient of non-photochemical burst (NPQ), maximum photosynthetic efficiency of photosystem II (Fv/Fm), vein area (LVA), leaf thickness (LT), and stomatal density (SD). The eastern slope exhibited peak values in net photosynthetic rate (Pn), stomatal conductance (Gs), water use efficiency (WUE), and electron transfer rate of photosystem II (ETR). In contrast, the northern slope showed the highest intercellular CO₂ concentration (Ci), coefficient of photochemical burst (qP), actual photosynthetic efficiency of photosystem II (Y(II)), vein density (VD), and leaf area (LA). Photosynthetic-fluorescence characteristics in C. multiflorus were significantly correlated with leaf traits, vein traits, and stomatal density, with VD and SD exerting the most pronounced influences. Photosynthetic physiology on southern and western slopes was differentially modulated by temperature and moisture factors, particularly vapor pressure deficit (VPD) and photosynthetically active radiation (PAR), while the eastern slope was primarily governed by moisture and nutrient availability. Northern slope plants experienced co-regulation by temperature, soil nutrients, and moisture, with soil organic carbon (SOC) and total phosphorus (TP) exhibiting dominant effects.ConclusionsThis research underscores slope-specific adaptive mechanisms and key drivers in C. multiflorus, informing scientific cultivation practices for shrub communities in arid ecosystems.

[This corrects the article DOI: 10.3389/fpls.2025.1562491.].

The response of leaf traits and photosynthetic characteristics to selenium (Se) application reflects plant adaptation strategies for selenium-enhanced accumulation of photosynthetic products. This study selected eggplant as the research subject and conducted a field experiment to better understand these relationships. This study included three Se treatments, foliar sprays of 0.5mgL-1 (T1), 1mgL-1 (T2), and 1.5mgL-1 (T3), with tap water as the control (CK). The results revealed that T1 and T2 significantly improved leaf traits and photosynthetic characteristics compared to CK, while T3 had a negative effect. Regarding the leaf area-leaf thickness (LA-LT) trade-off relationship, the T2 treatment favoured LA, whereas the CK, T1, and T3 treatments favoured LT, with trade-off values of T3>T1>CK. Regarding the net photosynthetic rate-transpiration rate (Pn -Tr ) trade-off relationship, the CK treatment favoured Tr , whereas the T1, T2, and T3 treatments favoured Pn , with trade-off values of T2>T1>T3. In T1 and T2, the eggplant specific leaf area and Pn showed non-significant and highly significant positive correlations, respectively, and in CK and T3 showed non-significant and highly significant negative correlations, respectively. These results indicate that foliar application of Se at appropriate concentrations can increase crop productivity in semi-arid areas.

The study of the spatial distribution pattern of soil fractal properties and its relationship with water-salt factors contributes to an in-depth understanding of the mechanisms by which the ecohydrological processes of inland salt marsh wetlands affect soil texture. In the wetland of Sugan Lake at the northern margin of the Qaidam Basin on the Tibetan Plateau, the single and multiple fractal dimensions and their influencing factors of four sample sites with different hydrological gradients from the lake shore to the peripheral uplands of Xiaosugan Lake were analyzed by combining field investigation and quantitative analysis. The results showed that from the lake shore to the peripheral uplands of Xiaosugan Lake, the soil texture demonstrate clear multifractal behaviour, with generalized dimension and multifractal singularity spectra showing inverse S-type curves and left-deviating. The degree of heterogeneity of soil textural homogeneity and particle size distribution frequency curves decreased and then increased, and the soil singularity fractal dimensions (Dv), capacity dimensions (D0), information dimensions (D1), correlation dimensions (D2), singular spectrum width Δα, and singular spectrum shape feature Δf showed U-shaped trends. Soil Dv, D0, D1, D2, Δα, and Δf were positively correlated with clay content, silt content, vegetative belowground biomass (BGB), and Ca2+, negatively correlated with the soil sodium adsorption ratio (SAR). Under the combined influence of wetland hydrological characteristics, ionic composition, and plant community characteristics, the soil fractal dimension of the Sugan Lake wetland showed a complex distributional evolution pattern, reflecting the interactive influence mechanism between soil structure and wetland biotic and abiotic factors in inland salt marsh wetlands.

Water use efficiency (WUE), as an indicator for plants to regulate water physiological processes through photosynthesis, is a key link between carbon and water cycling in ecosystems, reflecting the rapid adaptation strategies of vegetation ecosystems to site environment and resource changes. In this study, satellite data and ground-based observation data from 2001 to 2020 were developed to simulate and estimate the spatial distribution characteristics of WUE in different functional zones and analyze the time lag and cumulative effects of climate on vegetation. The results show that: (1) From 2001 to 2022, the multi-year average WUE in the Shiyang River Basin (SRB) was 0.99 gC·kg-1 H2O, exhibiting a spatial pattern of high values in the middle reaches and low values in the upper and lower reaches, with the highest value in Area II (1.23 gC·kg-1 H2O) and the lowest in Area IV (0.80 gC·kg-1 H2O). On a monthly scale, WUE showed an increasing trend in February and from November to December, and a decreasing trend in the remaining months. (2) Annually, WUE was significantly negatively correlated with air temperature and precipitation. However, the monthly responses varied significantly: WUE was positively correlated with air temperature from September to March and negatively correlated from April to August; WUE was negatively correlated with precipitation in all months, with the strongest negative correlation in June. Zone III was sensitive to air temperature, while Zone II responded more significantly to precipitation. (3) WUE responded to temperature changes with an immediate response (91.59% of the regions with a lag of 0 months), whereas it relied on a 3-month cumulative effect for precipitation (TLA0-3). The southwestern part of Region I exhibited a different lagged and cumulative response to climatic factors compared to other regions due to the cold and desert environments.

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 leaf area index (LAI) is a crucial vegetation parameter that characterizes leaf sparsity and canopy structure, and the study of the spatial distribution pattern of the forest LAI and its environmental response can help to reveal the adaptive capacity of forest vegetation to climate change in semiarid areas. In this paper, a remote sensing inversion model of the LAI, which pertains to the forest ecosystem of Xinglong Mountain in the transition zone between the Qinghai‒Tibet Plateau and Loess Plateau, was established by combining an optical instrumentation method, a remote sensing inversion method, and a generalized additive model (GAM). The results showed that (1) the Meris terrestrial chlorophyll index (MTCI) linear regression model provided the greatest explanatory power for the LAI in the Xinglong Mountain forest, with R2 = 0.88 and RMSE = 0.32. (2) The LAI was influenced mainly by the altitude, slope, profile curvature, aspect, planform curvature, temperature, precipitation, and evapotranspiration. According to the single-factor GAM, altitude (R2 = 0.43) explained most of the total variation in the LAI, followed by precipitation (R2 = 0.36). According to the multifactor GAM, the above influencing factors could explain 84.2

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.