Physiological response strategies of pioneer endemic species Artemisia wudanica along an aeolian disturbance gradient in semi-arid active sand dunes.

INTRODUCTION

Wind erosion and sand burial are recurrent but physically distinct aeolian disturbances in semi-arid dune systems. We investigated how Artemisia wudanica seedlings respond physiologically to matched relative gradients of simulated substrate removal and sand burial under controlled pot conditions.

METHODS

Seedlings were subjected to five simulated wind-erosion levels (0, 2, 4, 6, and 8 cm) and five sand-burial levels (0, 1.7, 3.3, 5.0, and 6.7 cm). Chlorophyll, proline, soluble sugar, malondialdehyde (MDA), peroxidase (POD), and superoxide dismutase (SOD) were quantified. Treatment effects were evaluated using two-way ANOVA, PCA of standardized variables, disturbance-specific Spearman correlations, and an exploratory path analysis.

RESULTS

Disturbance type, relative disturbance level, and their interaction affected all six physiological traits, and PCA separated the two-treatment series in multivariate space. Under sand burial, chlorophyll, proline, and soluble sugar showed positive within-treatment covariation after Spearman correlations. Under simulated wind erosion, POD and SOD covaried positively, whereas MDA was not significantly correlated with either antioxidant enzyme; chlorophyll-proline and soluble sugar-MDA associations also remained significant after correction. The exploratory path model had limited overall fit and was used only to summarize statistical associations, not to establish causal physiological mechanisms.

DISCUSSION: Under the controlled conditions of this seedling experiment, the two isolated treatments were associated with different physiological response and covariation patterns. These results provide testable hypotheses about disturbance-specific seedling responses rather than evidence of switchable association, population-level persistence, or restoration performance. Validation is required under field conditions, across additional life stages, and with pulsed and combined erosion-burial events.