Weed Seedbank Dynamics and Species Turnover in Intensively Managed Vegetable Fields Over a Five-Year Period

Abstract

Long-term changes in weed seedbanks and species composition play a critical role in determining the sustainability and effectiveness of weed management programs in intensive vegetable production systems. Field investigations were conducted over a five-year period to evaluate weed seedbank dynamics, species turnover, and community shifts in intensively managed vegetable fields subjected to repeated cultivation and weed control practices. Soil samples were collected annually from different depths and analyzed to determine seed density, species richness, and temporal variation in weed populations. Phytosociological assessments and emergence observations revealed substantial fluctuations in weed community structure throughout the study period. Repeated cropping and intensive management practices significantly altered the abundance and persistence of dominant weed species within the soil seedbank. Certain annual broadleaf weeds and grasses declined progressively due to continuous control measures, whereas several adaptable and stress-tolerant species increased in relative dominance over time. Species turnover analysis indicated that environmental conditions, tillage intensity, irrigation frequency, and herbicide application strongly influenced weed succession patterns and community composition. Persistent seedbank reserves enabled some weed species to re-establish rapidly despite repeated suppression efforts. Shifts toward herbicide-tolerant and fast-emerging weed species were observed in fields exposed to similar management practices over consecutive seasons. Seasonal climatic variation also contributed to differences in germination behavior and recruitment dynamics among weed species. Weed seed density generally declined during the initial years but stabilized later due to continuous replenishment by surviving individuals and newly introduced propagules. The findings highlight the ecological complexity of weed population dynamics in intensive vegetable systems and emphasize the importance of diversified management strategies to prevent dominance of problematic weed species.