Shrub species identity modulates plant–arthropod diversity coupling across a dryland aridity gradient

Shrubs are key ecosystem engineers in drylands, yet their effects on biodiversity range from strongly positive to negative depending on species identity and climatic stress. A critical knowledge gap remains in understanding how shrub species identity modulates plant–arthropod biodiversity and their coupling across aridity gradients.

To address this gap, we examined the diversity of herbaceous plants and ground‐dwelling arthropods, along with soil properties, in microhabitats formed by native Artemisia ordosica , planted Caragana korshinskii and adjacent open spaces. This study spanned three consecutive years along a pronounced aridity gradient in northern China.

Our findings revealed that C. korshinskii shrubs exerted a neutral effect on herbaceous diversity even under high aridity, whereas A. ordosica shrubs inhibited herbaceous diversity, with suppression intensifying as aridity increased. Contrastingly, neither shrub species affected arthropod diversity across the full aridity gradient. Furthermore, a consistently close and strong plant–arthropod diversity coupling was observed across the three microhabitats. Along the aridity gradient, the C. korshinskii shrubs maintained a stable and high coupling, whereas the A. ordosica shrubs maintained a low coupling, comparable to open spaces. Where, the coupling reduced along aridity, exhibiting a threshold (~270 mm) below which the coupling weakened.

Synthesis . Together, these results suggest that shrub species identity is a decisive regulator of plant and arthropod diversity and their coupling across aridity gradients. C. korshinskii maintains a stable and high‐coupling strategy, while A. ordosica exerts a low‐coupling strategy along aridification. These findings provide a mechanistic foundation for incorporating shrub identity into climate‐adaptive restoration strategies in dryland ecosystems.