Effects of sweet potato (Ipomoea batas) cultivation on the community composition and diversity of weeds in arid fields

Abstract

For developing ecological prevention and management techniques for invasive and dominant weed species, the screening and using of high value species with strong competitive ability (e.g., local food, native species and/or cash crops) have captured widely attention. To explore the effects of sweet potato (Ipomoea batas) cultivation on community composition and species diversity of weeds, the composition, density, importance value, species richness, diversity indices, and Pielou index were analyzed under five different cover scenarios (0%, 1–25%, 26–50%, 51–75, 76–100%). The study took place in arid cultivated fields in Jianshui County, Yunnan Province, China. A total of 25 weed species from 18 families were identified. Of these, four invasive species Ageratum conyzoides, Bidens pilosa, Eleusine indica, and Galinsoga parviflora and two native species, Digitaria sanguinalis and Portulaca oleracea had the highest population density and were most dominant. Population density and importance values of the six dominant weed species declined as sweet potato cover increased. A significant negative correlation was observed between importance values and sweet potato cover (P<0.05). Population density of two less dominant native species, Calystegia hederacea and Poa annua, increased significantly with increasing sweet potato cover. Similarly, the importance values for two additional native species Acalypha australis and Echinochloa crusgalli was positively correlated with sweet potato cover (R=0.964, R=0.891, P<0.05). Maximum values for species richness (23.5, 24.5), Simpson index (0.89, 0.85), Shannon-Wiener index (2.36, 2.35) and Pielou index (0.75, 0.73) corresponded to sweet potato cover ranges of 1–25% and 26–50% respectively. As sweet potato cover increased species richness and diversity values significantly declined. Overall, the results indicate that the cultivation of sweet po486 生 物 多 样 性 Biodiversity Science 第 22卷 tato alters the community composition and diversity of weeds limiting the occurrence of the dominant and invasive weed species. As a result, mid to low percent cover values should be considered an effective and ecologically-based weed management strategy to replace herbicide use in arid fields.