不同生长年限黄芪田间杂草群落结构特征

Weed community structure in fields of Astragalus membranaceus of different ages

杂草是抑制药用植物生长发育,影响其产量和质量的主要生物因子。黄芪为多年生药用植物,在其生长过程中田间杂草群落结构不断发生变化。通过田间调查统计发现整个黄芪田中杂草有66种,分属24科59属。其中以菊科和豆科杂草种类最多,分别有10种。优势种有冰草、狗尾草、虫实、田旋花、苦荬菜等。不同生长年限黄芪田中杂草群落结构不同,一年生黄芪田间杂草丰富度、Shannon-Wiener指数和Pielou指数均最低(32、1.71、0.49),Simpson指数最高(0.372),杂草集中度高。十年生黄芪田间杂草的Shannon-Wiener指数和Pielou指数均最高(3.14、0.82),Simpson指数最低(0.068),群落结构趋于稳定。生长年限相近的黄芪田杂草群落结构特征相近,以三年生与五年生黄芪田最为相似,Sorenson指数最高(0.828)。伴随年限的增加,黄芪田中杂草群落优势种变化趋势为"一年生种子植物-多年生小草本-多年生大草本/小灌木",建群植物变化趋势为"虫实-冰草-醉马草/冷蒿"。黄芪田中杂草主要有两大类传播方式:以种子传播的游击战模式和以根茎走窜传播的根据地模式,分别以虫实和冰草为代表植物。

Weeds are the main biological factors that inhibit the growth,development,yield,and quality of medicinal plants.Astragalus membranaceus is a perennial medicinal plant,and the structure of the weed community structure in fields of this species evolves continuously during its growth.We conducted field surveys and found 66 species of weeds belonging to 24 families and 59 genera in A.membranaceus fields.Members of the Compositae and Leguminosae were the most abundant,with 10 species in each family.The dominant weed species were Agropyron cristatum,Setaria viridis,Corispermum mongolicum,Convolvulus arvensis,and Ixeris polycephala.The weed community structure differed among fields of A.membranaceus plants of different ages.In fields of annual A.membranaceus,the weed community had low values for richness,the Shannon-Wiener index,and the Pielou index(32,1.71,0.49),a high value of Simpson’s index(0.372),and large biomass.In a field of 10-year-old A.membranaceus,the weed community had high values of the Shannon-Wiener index(3.14)and Pielou index(0.82),a low value of Simpson’s index(0.068),and the community structure tended to be stable.The weed community structure was similar among fields of similarly aged A.membranaceus plants,especially 3-to 5-year-old plants Sorenson’s index(0.828).With increasing age of A.membranaceus plants,the dominant species in the weed community changed from annual seed plants to perennial small herbs to perennial large herbs/small shrubs,and the main species of community-building plants changed from C.mongolicum to A.cristatum to Achnatherum inebrians and Artemisia frigida.We detected two main modes of weed propagation in A.membranaceus fields:The guerrilla warfare mode of seed propagation exemplified by C.mongolicum;And the base area mode of rhizome propagation exemplified by A.cristatum.