关键词: 黄淮海地区, 冬小麦田, 禾本科杂草, 时空分布, 相对优势度

Abstract:

【Objective】This study aims to reveal the spatiotemporal variation of five major grass weed species, including Lolium multiflorum, in winter wheat fields of the Huang-Huai-Hai region over the past decade, and to provide a basis for regional weed monitoring, early-warning and precision management.【Method】Two rounds of systematic surveys were conducted in winter wheat fields across the Huang-Huai-Hai region in 2013 and 2023 using an inverted “W”-shaped nine-point sampling method. The distribution ranges and infestation levels of five dominant grass weeds, including Aegilops tauschii, Bromus japonicus, Lolium multiflorum, Alopecurus myosuroides and Avena fatua, were recorded. The relationships between relative abundance (RA) and longitude/latitude were analyzed to characterize spatiotemporal distribution patterns.【Result】The spatiotemporal changes in grass weeds in winter wheat fields of the Huang-Huai-Hai region were mainly reflected in the following aspects: (1) The relative abundance of four grass weeds, L. multiflorum, A. tauschii, B. japonicus and A. myosuroides, increased continuously, whereas that of A. fatua decreased slightly. In 2013, B. japonicus and A. tauschii showed the highest RA values in the region, together accounting for more than 15%, followed by A. fatua (2.51%), while L. multiflorum and A. myosuroides both had RA values below 2.5%. By 2023, the RA of A. tauschii (11.66%) and B. japonicus (11.22%) increased markedly. The maximum increase observed for A. tauschii was 8.72%, whereas B. japonicus exhibited increases ranging from 0.43% to 10.44%. The regional mean RA of L. multiflorum increased to 2.88%, exceeding that of A. fatua (2.14%) and becoming the third most abundant species. (2) Spatially, the infested area of L. multiflorum, A. tauschii, B. japonicus and A. myosuroides expanded continuously, while the distribution range of A. fatua shrank slightly. A. tauschii and B. japonicus expanded continuously eastward and southward from their traditional high-incidence belts in the western and northern Huang-Huai-Hai region; by 2023 they almost covered all major winter wheat production areas across the entire region, and relatively stable populations had formed in previously blank or sporadically infested areas such as the Huaibei region of Anhui and Jiangsu as well as Tianjin. In 2013, L. multiflorum and A. myosuroides occurred only sporadically in a few prefecture-level cities; ten years later, L. multiflorum was recorded in about 60% of the surveyed prefecture-level cities, rapidly shifting from “localized point occurrence” to a pattern of “southern concentration with regional spread”, and forming new high-incidence belts in central-southern Henan, northern Anhui, northern Jiangsu and the Guanzhong Plain, indicating strong expansion momentum and substantial potential risk. A. myosuroides formed concentrated high-incidence areas in the Guanzhong Plain, central-southern Henan, northern Anhui and central-southern Hebei, with its overall pattern changing from “point-like occurrence” to “patch-like expansion”. In contrast, the overall distribution range of A. fatua decreased; it was no longer recorded in some central and northern prefecture-level cities, and its main high-incidence belt shifted from the previous “wide distribution in southern and western areas” to localized concentration in central-southern Henan, northern Anhui and the Guanzhong Plain, showing a “southward contraction” pattern. (3) Correlation analyses showed that in 2013 the RA of A. tauschii was significantly negatively correlated with longitude, whereas in 2023 it was significantly positively correlated with latitude, indicating a weakened east-west gradient and an enhanced north-south gradient. The RA of B. japonicus increased highly significantly with latitude in both surveys, and in 2023, also showed a significant increasing trend with longitude. The RA of L. multiflorum and A. fatua generally decreased with increasing latitude and longitude, while A. myosuroides showed no consistent or significant correlation.【Conclusion】Over the past decade, major grass weeds in winter wheat fields of the Huang-Huai-Hai region have undergone marked spatiotemporal expansion, accompanied by increasing relative abundance. These changes are driven by the combined effects of alien invasion, conservation tillage, long-term reliance on single-site-of-action herbicides, and cross-regional movement of agricultural machinery and seeds. Accordingly, region-specific systems for weed monitoring, early warning, and integrated management, together with optimized tillage practices and herbicide mode-of-action rotations, are required to enable precision control of grass weeds across the Huang-Huai-Hai winter wheat system.

Key words: Huang-Huai-Hai region, winter wheat field, grass weed, spatiotemporal distribution, relative abundance