Through permanent plot-based ecological monitoring of five representative mangrove communities (Kandelia obovata-Aegiceras corniculatum community, K. obovata community, K. obovata-Avicennia marina community, A. marina community, and artificial forest) in the Mangrove Nature Reserve of Shenzhen Bay, combined with measurements of leaf functional traits and sediment physicochemical parameters, this study elucidates the population distribution pattern, asexual reproduction dynamics and ecological strategies of the understory A. ilicifolius population under the background of terrestrialization. The results show that A. ilicifolius has become the dominant understory species (importance value: 85.38%), with an aggregated distribution pattern (K<0) and a uniform distribution (PAI=1, C<1). The population density of mature individuals showes slow expansion(1991–2011), rapid growth (2011–2019: 0.03→16.84±13.11 plants/m²), and stabilization by 2023 (17.26±7.03 plants/m²). Clonal reproduction is one of the key strategies for the A. ilicifolius population to dispersal. A. ilicifolius exhibits stoloniferous clonal growth with guerrilla architecture, characterized by a mean spacer length (41.26±32.92 cm) and monthly elongation rate (1.29±0.66 cm/month), reflecting an expansion-growth (escape strategy) under low-light understory habitats. High-sedimentation zones trigger an ecological strategy shift from CS to C or CR, manifested by increased canopy height and long-spacer stolon extension. This study provides early-warning data for mangrove ecological risks.