Objective Artemisia ordosica, a key nursery shrub species in the Mu Us Sandy Land of northern China, plays an important role in vegetation restoration and biodiversity conservation. However, its effects on conspecific seedlings and the underlying mechanisms remain unclear. This study focused on two major limiting factors of light and water to examine how low-light and water-retentive microenvironment within shrub canopies influenced seedling growth performance and functional traits.

Method A three-factor controlled experiment was conducted with light (full light vs. shade), water (high vs. low), and soil origin (under-canopy vs. interspace). Seedling biomass, as well as key leaf and root functional traits were measured. Analysis of variance, correlation analysis, and structural equation modeling were used to disentangle the direct and interactive effects of light, water, and soil on seedling growth strategies.

Result (1) Light availability was primary factor limiting the growth of conspecific seedlings beneath shrub canopies, with shading reducing total biomass by 30%−50%. (2) Increased water availability significantly promoted seedling growth only under full light conditions, whereas this effect was substantially weakened under low light. Although seedlings exhibited compensatory traits under shade (e.g., increased specific leaf area), these adjustments did not offset carbon limitation caused by reduced light availability. (3) Structural equation modeling indicated that leaf area acted as a key mediating trait linking light and water availability to seedling growth, with light exerting the strongest direct and indirect effects on biomass.

Conclusion Although A. ordosica shrubs can improve local moisture, the low-light environment it creates becomes a core factor limiting the regeneration of conspecific seedlings, partially transforming the conservation effect into intraspecific negative feedback of the “self-inhibition” type during the seedling stage. The limited capacity of seedlings to adapt to low-light conditions is a major factor restricting regeneration within shrub canopies, whereas soil effects are relatively minor during early growth. This study highlights the dual role of nursery shrubs in arid ecosystems and provides new empirical evidence for understanding population dynamics and spatial pattern formation.