## 1 Introduction  
In recent years, scholars have increasingly focused on studying plant roots and their role in soil consolidation and erosion resistance in the riparian zone. Severe soil erosion has become a significant ecological and environmental problem in the riparian zone [1]. The management of the riparian zone primarily involves restoring vegetation. Plant roots play a crucial role in consolidating soil and enhancing soil erosion resistance [2; 3]. An important indicator for evaluating the soil consolidation ability of plant roots is the increase in the soil's shear strength due to the presence of plant roots [4]. Herbaceous plant roots, as natural bio-fibers, possess a certain tensile strength and contribute to reinforcing the soil to enhance its shear strength. Plants exhibit good soil consolidation and erosion resistance, which is evident in both their above-ground and below-ground roots. On one hand, plants serve a buffering function by obstructing rainfall, runoff, and waves with their above-ground parts, thereby reducing the intensity of erosion. On the other hand, plant rootsinterlace and intertwine in the soil to withstand external erosive forces through a network structure, retaining and anchoring the soil, thus stabilizing it and enhancing its resistance to erosion [5].  
Most current studies have primarily focused on herbaceous plants like _Cynodon dactylIon_ in the riparian zone of the Three Gorges reservoir. These studies have mainly analyzed the relationship between root morphology and root mechanical properties of the dominant species in the riparian zone. For example, [PERSON]. [PERSON] et al., 2023 [6] and [PERSON] et al., 2018 [7] demonstrated that plant roots could significantly improve the water erosion resistance and shear strength of soil. [PERSON] et al. conducted hydrostatic disintegration tests, while [PERSON] et al. performed direct shear tests on soil samples containing roots. [PERSON] et al., 2022 [8] and [PERSON] et al., 2021 [9] studied the tensile properties of herbaceous roots and predicted the soil-fixing ability by using the single-root tensile test. They pointed out that herbaceous roots had excellent soil-fixing ability. Among them, the Pioneer species of _Artemisia capillaries_ and _Leymus secalinus_ had a high soil detachment capacity 6.32-12.57 times greater than that of late-succession species. The highest root tensile strength measured was for _P. paspaloides_ (62.26 MPa), followed by _Cynodon dactylIon_ (51.49 MPa), _H. compressa_ (50.66 MPa) and _H. altissima_ (48.81 MPa). The high root cohesion of _H. altissima_ and _H. compressa_ means that they are suitable for revegetation [10; 11]. Fewer studies have been reported on plant investigations in the riparian zone of reservoirs in the ecologically fragile areas of the dry and hot river valleys in the Yunnan-Guizhou Plateau region. Further research on plants in the riparian zone with varying inundation gradients is needed to analyze their root growth morphology and root mechanical properties in response to changes in inundation time.  
In this paper, we investigated the interrelationship between these characteristics and elevation by studying the root morphology and root tensile resistance characteristics of the dominant species, _Cynodon dactylIon_. The focus was on the representative Ertan Reservoir in the Yalong River riparian zone and Guanyinyan Reservoir in the Jinsha River riparian zone. Our research results will provide important references for ecological restoration and construction at different riparian elevations.