Dominance Patterns of Weed Communities Across Rice Landscapes in the Vietnamese Mekong Delta: Implications for Ecological Weed Management

Abstract

ABSTRACT Effective weed management requires more than a species inventory; it requires evidence that the same taxa dominate occurrence, density, biomass, and canopy occupation and that dominance varies spatially. We surveyed 120 rice fields across 16 localities in former Hau Giang Province, now part of Can Tho City, in the Vietnamese Mekong Delta. Weed communities were assessed in 1200 1‐m 2 quadrats distributed equally between field interiors and bunds. Occurrence, density, field uniformity, fresh and dry biomass, canopy cover, composite dominance indices, qualitative functional categories, and locality‐level similarity were quantified. Forty‐eight species from 15 families were recorded; Poaceae accounted for 25 species (52.1%). Four taxa formed a consistent management‐priority core: Echinochloa crus‐galli , Oryza sativa f. spontanea , Leptochloa spp., and Fimbristylis miliacea . Together, they represented 91.6% of relative mean field density, 90.1% of relative canopy cover, 90.4% of relative fresh biomass, and 99.3% of relative dry biomass. E. crus‐galli ranked first in composite importance value (111.92). Presence‐absence indices indicated a broadly shared regional species pool, whereas abundance‐weighted similarity showed substantial differences in dominance among localities. The findings support a two‐scale management strategy: regional surveillance of the four recurrent priority taxa combined with field‐specific adjustment of water management, crop establishment, control timing, sanitation, and seedbank suppression.