Multivariate analysis, description, and ecological interpretation of weeds and alien invasive weeds in the autumn tea gardens of Jiangsu Province, China.
To investigate the effects of herbicide use, tillage, tree age, slope, and canopy density on the weed species composition and community structure in autumn tea gardens in Jiangsu Province, 90 representative sampling sites of Yizheng, Jintan, and Yixing were selected, and weed surveys were conducted in October 2013. The 90 sampling sites were classified into three groups based on the dominant weed species and weed abundance according to canonical correspondence analysis (CCA) and principal component analysis (PCA). The Group I consisted of Arthraxon hispidus, Geranium carolinianum, Oxalis corniculata, Setaria viridis, Rubus hirsutus, and Ophitopogon japonicum, and these species were present in all sample sites from the tea gardens with lower frequencies of tillage and herbicide application, older trees, and higher canopy densities. This community had more perennial weeds and weed species and a lower weed density. The Group II consisted of Digitaria sanguinalis, Echinochloa crus-galli var. austro-japonensis, Conyza canadensis, G. carolinianum, and S. viridis. All the sample sites in this group relied primarily on chemical control of weeds, and therefore more annual grassy malignant weeds, herbicide-tolerant weeds, and prominent dominant weed species were present. The Group III contained D. sanguinalis, E. crus-galli, Eleusine indica, G. carolinianum, O. corniculata, and Leptochloa panacea. Because the tea gardens of this group were intensively managed, fewer dominant weed species were present, and weed density was lower. Moreover, analyses of alien invasive weed species and environmental factors indicated that herbicide application and tillage highly significantly affected the occurrence and distribution of alien invasive weeds in autumn tea gardens in Jiangsu Province. The results indicated that different management practices, e. g., herbicide application and tillage practice, play decisive roles in the formation of weed communities.