Optimal Stubble Management Strategies of Caragana tibetica for Enhancing Stress Resistance and Vegetation Restoration

<i>Caragana tibetica</i> Kom. is a key constructive species in desert steppe and desert transition zones. Long-term enclosure has led to population decline and even mortality of <i>C. tibetica</i>, while populations outside enclosures grow well. However, the biological mechanisms underlying the continued growth of <i>C. tibetica</i> under grazing remain unclear. Therefore, this study aimed to clarify the effects of stubble management on the photosynthetic physiology and antioxidant characteristics of <i>C. tibetica</i>, and to determine the optimal stubble intensity. Plants were subjected to five stubble gradients (0%, 25%, 50%, 75%, 100%). The results showed that stubble treatments caused significant changes in both photosynthetic and antioxidant traits. Interestingly, the correlations between photosynthetic and antioxidant characteristics varied with the growth season: they were positively correlated in the early growth season, but negatively correlated in the middle and late stages. Using a generalized algorithmic model, we found that stubble intensities ranging from 0.5% to 38.7% enhanced the stress resistance of <i>C. tibetica</i>, with 21.6% being the optimal intensity. This study demonstrates that moderate stubble management promotes the stress resistance of <i>C. tibetica</i>, providing important theoretical and scientific support for vegetation restoration and ecological construction in desert steppes.