ABSTRACT Liverworts belong to the oldest vascular‐free bryophytes, and thus with their preserved and unique hydrological processes, they may be the most appropriate models of plant–ecosystem interaction. Their adaptability and their simple morphology are conducive to a detailed structural examination. Some species of liverworts ( Calypogeia arguta , Metzgeria conjugata , Clevea hyalina and Riccia papillosa ) are mentioned for the first time in Uzbekistan. Annotation contains the data about their distribution, habitat, and location. The paper introduces the novel records of four liverworts, and their analysis by stereomicroscopy and light microscopy (LM). The new species recorded were C. arguta , M. conjugata , C. hyalina and R. papillosa . Microscopy characterization visualized detailed data on the following leaf characteristics: C. arguta presented minute papillae and irregular cells of the epidermis; M. conjugata presented a surface of high texture with small protrusions; C. hyalina presented a smooth shiny surface with only surface structures; and R. papillosa presented a rough texture surface with closely packed papillae. The results broaden the hypothesis of the bryoflora according to which the liverworts, due to the target micromorphological changes, can serve minor functions in the control of moisture in the microhabitat and during the initial phases of ecological vegetation and stability in riparian habitat.

ABSTRACTThe relationship between near‐bed hydrodynamics, pore‐water chemistry and the presence of unionids was examined in a well‐characterized multispecies mussel bed (26 species; ~24 mussels m−2; 70% gravel, 20% cobble and 10% sand) within a lowland river (Sydenham River) in southern Ontario, Canada. Local bed shear stress (τb) was determined from velocity profiles at ~1‐m intervals along four laterals and three longitudinal transects in the reach providing 118, 14.3‐cm diameter quadrats in which porewater was sampled and sediments were excavated for unionids. Ninety‐four unionids (10–135 mm long) from 14 species were found in 56 quadrat locations that had significantly higher mass of very fine gravel (2000‐μm sieve) and lower dissolved oxygen in a comparison of individual environmental factors. Larger adult mussels (i.e., > 30 mm long; n = 68) were found in quadrats with τb = 0.022–1.34 Pa and an excavated very fine gravel mass = 616–2821 g, but smaller, juvenile mussels (< 30 mm; n = 26) were found in a more restricted range of τb and sediment content (0.075–0.77 Pa and 1151–2561 g, respectively). Using forward and backward stepwise habitat variable selection in logistic regression, models incorporating τb, τb2 and/or very fine gravel mass provided the highest probability of locating juvenile mussels. The final model, which is based on body size, is informative at the community level rather than on a species‐specific basis. These results provide insights into the relationship between near‐bed hydrodynamics and these important benthic invertebrates, the location of small juvenile and larger adult unionids and their habitats in riverbeds. Conservation efforts should focus on preserving and enhancing these habitats and those of the most vulnerable early life stages of freshwater mussels.

ABSTRACT Plant surface water storage (PWS) greatly affects canopy rainfall interception and thus has a significant impact on water availability for plants under drought conditions. However, it remains unclear whether the responses of PWS characteristics of dioecious plants exhibit sexual dimorphism under drought stress and how these responses relate to plants' drought resistance. To this end, the impact of drought on the PWS characteristics, related leaf traits and biomass accumulation of Spinacia oleracea males and females was investigated. Under normal water conditions, PWS per unit total dry weight and per unit leaf area of females were 52.8% and 42.1% lower than those of males, respectively, indicating a potentially higher PWS efficiency of males. Under drought conditions, PWS per unit total dry weight and per unit leaf area in males decreased significantly by 24.9% and 62.7%, respectively, while those in females remained unchanged, implying greater sensitivity of males' PWS efficiency to drought. The PWS capacities of the stem, leaves and entire plant were similar between males and females under normal water conditions, but the males exhibited a greater reduction under drought. Female plants showed a 20.4% lower reduction in leaf dry weight and a stronger increase in leaf density under drought than males, reflecting stronger drought resistance in females. Analysis based on leaf hydraulic characteristics suggested that both sexes might enhance their foliar water uptake, as indicated by larger contact area of water drop on leaf surface due to improved leaf wettability (lower leaf contact angles) and better structural basis for foliar water absorption due to higher leaf succulence indexes under drought. However, females might benefit more from these adaptations due to their undiminished PWS efficiency. These results suggested that deriving greater benefits from foliar water uptake through maintaining stable rather than decreased PWS efficiency may be one of the reasons why female S. oleracea plants exhibit stronger drought resistance than the males.

ABSTRACT Although several studies regarding flow resistance due to aquatic vegetation for small‐ and full‐scale are available, the scaling of small‐scale results to full‐scale conditions still needs to be investigated. In this paper, a theoretical flow resistance equation for open channels was tested using literature measurements performed for full‐scale field channels and small‐scale experimental flumes with aquatic vegetation. At first, the relationship between the scale factor Γ of the velocity profile, the Froude number and the channel slope was calibrated by using 27 field measurements by Nikora et al. (2008). This relationship was also tested by 39 field experimental series by Okhravi et al. (2022). Then, the proposed relationship for estimating Γ was coupled with the theoretical flow resistance law to assess the performance in the estimate of the Darcy–Weisbach friction factor values. The results demonstrated that the proposed approach gives a more accurate estimate of the Darcy–Weisbach friction factor as compared to that obtained applying the literature relationships. The relationship between Γ, the Froude number and the channel slope obtained for the field condition was recalibrated by flume data changing only the scale coefficient. The analysis demonstrated that, for known hydraulic conditions (slope, Froude number), for scaling the Γ values estimated by field data (streams, rivers), Γ F , to values corresponding to laboratory conditions (flumes) Γ L , a scale factor of 0.5356 must be used. In conclusion, comparing the same hydraulic conditions, streams or rivers are characterized by friction factor values approximately twice those of a laboratory flume.

ABSTRACTHydropower development significantly impacts the fragile fish habitats in river reaches of the Tibetan Plateau. To support the conservation of fish resources in these reaches, this study developed a physical habitat evaluation model for spawning grounds based on the ecological requirements of key fish species. An artificial neural network (ANN) model was employed to fit the response relationships between spawning ground indicators and environmental factors. Results indicate that water temperature is a critical factor influencing spawning grounds. In natural river reaches, suitable spawning periods occur primarily in the afternoon. In contrast, water temperature in dam‐downstream reaches is significantly affected by hydropower operations, leading to distinct differences in spawning rhythms compared to natural reaches. The Weighted Usable Area (WUA) and Patch Number (PN) of spawning grounds initially increase and then decrease with rising flow. The ANN model effectively fits the response relationships between environmental factors and WUA and PN (R2 > 0.87). Water temperature exhibits a stronger influence, while flow primarily affects WUA and PN by altering suitable substrate area. This study presents the development and application of physical and ANN models for fish spawning grounds in hydropower‐affected river reaches of the Tibetan Plateau. The findings reveal the distribution patterns of spawning grounds and identify key environmental factors. These results provide methodological references and scientific evidence for the evaluation and conservation of fish resources, supporting the sustainable management of native fish populations in plateau rivers.

ABSTRACTThe plant communities of Poyang Lake, constituting the foundational element of the wetland ecosystem, are integral to crucial ecological processes including energy flow, biodiversity sustenance, water purification and hydrological regulation. Consequently, they serve an irreplaceable function in preserving the stability and ecosystem services of the region. This study uses Landsat 8, Sentinel‐2 optical images and Sentinel‐1 SAR images as data sources to extract spectral reflectance, index features and texture features from optical images as well as radar backscattering features from SAR images, constructing a multidimensional feature dataset. The Recursive Feature Elimination algorithm is employed to perform feature optimization on the dataset. Three classification schemes with different feature combinations are designed, and based on the random forest classifier, the impacts of multisource data fusion and feature optimization on the accuracy of plant community identification are investigated. The results demonstrate that the feature optimization‐based classification scheme attains the highest accuracy, reaching 93.42% overall accuracy with a Kappa coefficient of 0.93. Meanwhile, the optical‐SAR data fusion scheme shows significantly superior performance compared with the optical‐only scheme, delivering a 13.04% enhancement in overall classification accuracy. This study provides a scientific reference for remote sensing classification of wetland plant communities and supports biodiversity conservation and ecological management in the Poyang Lake wetland.

ABSTRACT The ordinary high water mark (OHWM) delineates the water environment from the land environment. The preferred method for the OHWM delineation in Québec, Canada, is a method based solely on bank vegetation characteristics, positioning the botanical OHWM (BOHWM) at the transition from hydrophytic to terrestrial vegetation. However, in anthropized landscapes, the implementation of this botanical method is problematic due to vegetation disturbance on the shoreline or riverbanks. The hydraulic and geomorphological methods position the OHWM at the 2‐year flood line and at the bankfull level of the river, respectively. The aim of this study was to compare the position of the 2‐year flood line to the BOHWM and to the geomorphological bankfull level for rivers located in agricultural, urban and forest areas. Results showed that the best concordance between the 2‐year flood line and the BOHWM was in agricultural areas (mean distance = 1.31 m) and the least in forest areas (mean distance = 3.31 m). The best agreement between the 2‐year flood line and the geomorphological method was found in agricultural (mean distance = 1.27 m) and urban (mean distance = 1.67 m) areas, while these two methods disagreed the most in forest areas (mean distance = 3.55 m).

ABSTRACTPinus ponderosa is a widespread conifer species across western North America, yet its intraspecific variability in drought response remains understudied, particularly at subseasonal time scales. We investigated how intraspecific tree dominance influences physiological and anatomical growth responses to warm‐season precipitation pulses in a semi‐arid montane forest in southern Nevada, USA. Using high‐resolution dendrochronology, quantitative wood anatomy and dual‐isotope (δ18O, δ13C) analysis of tree‐ring cellulose, we compared dominant (old‐growth) and codominant (mature) trees during two growing seasons: one impacted by a remnant tropical storm that provided an uncharacteristic pulse of precipitation to southern Nevada during the monsoon season (2015) and one with drier conditions with little monsoonal precipitation (2016). Codominant trees exhibited stronger and more immediate growth responses to warm‐season precipitation, characterized by increased tracheid production and cellulose δ18O values that matched those of warm‐season precipitation δ18O values, indicating shallow soil water use. In contrast, dominant trees relied more on deeper soil moisture and showed more conservative growth strategies. These divergent strategies suggest that intraspecific dominance mediates access to water and controls the sensitivity of growth to seasonal precipitation variability, highlighting the importance of intraspecific variation in shaping forest resilience and climate adaptation strategies under increasing drought and climate extremes.