Abstract: Modern urban agriculture in Haidian District is much more frequently and directly affected by human beings, making it more susceptible to alien plant invasion. In this study, we improved the basic dataset of agricultural alien invasive plants in Haidian District and comprehended the invasive status of agricultural invasive plants, aiming to provide a basis for the prevention and control of alien invasive plants, biodiversity conservation, and ecological security management. We preliminarily surveyed alien invasive plants at 48 sites in five agricultural towns in Haidian District. We collected data of habitats, investigation area, species composition, and damage objects, consulting the literature to obtain characteristic information, such as origin and life form. According to the preliminary results, we selected 12 heavily harmful and widely distributed species, including Ipomoea purpurea and Amaranthus retroflexus, for plot inventory, and quantified the damage level by average coverage. A total of 18 families, 35 genera, and 55 species of invasive plants were recorded across the five agricultural towns in Haidian District. Dicotyledonous plants (16 families, 32 genera, and 52 species, accounting for 94.5%) were the dominant. Meanwhile, Compositae and Amaranthaceae were the dominant families, with 18 (32.7%) and 10 species (18.2%), respectively. Furthermore, annual herbaceous plants (37 species, 67.3%) were the most common life form. Most alien species originated from North America (29 species, 52.7%), followed by South America (17 species, 30.9%). Ipomoea purpurea, Amaranthus retroflexus, Ipomoea hederacea, Erigeron canadensis, Bidens bipinnata, Abutilon theophrasti, Amaranthus blitum, Amaranthus viridis, Helianthus tuberosus, Xanthium italicum, Galinsoga parviflora, and Galinsoga quadriradiata were all widely distributed (with occurrence frequency over 40%) and extremely harmful (other than Erigeron canadensis and Abutilon theophrasti). In Haidian District, there were numerous agricultural alien invasive plant species with wide distribution and serious damage. We suggest that field investigations and monitoring of alien invasive plants should continue, the professional ability of technicians should be improved, and the alien invasive plants list and science popularization education should be expanded.

Key words: Haidian District, alien invasive plant, distribution pattern, damage level, prevention and control suggestion