耕作方式对新垦沙地农田杂草群落结构的影响

通过田间调查的方式,研究了黑河中游边缘绿洲新垦沙地农田杂草分布状况,并对不同耕作方式下农田杂草群落结构特征进行了分析。调查中共记录杂草16种,隶属10科。新垦沙地农田杂草群落基本组成为藜(Chenopodium album)+牛筋草(Eleusineindica)+狗尾草(Setaria viridis)+反枝苋(Amaranthus retroflexus)。与当地传统的地膜覆盖、秋耕和玉米连作耕作方式相比,秸秆覆盖、减少秋耕和玉米-大豆轮作均可增加农田杂草物种丰富度、多样性指数和群落优势度(P0.05)。与当地传统耕作方式相比,秸秆覆盖可增加杂草群落中牛筋草优势度比,降低藜和反枝苋优势度比;减少秋耕可增加狗尾草、反枝苋、灰绿藜(C.glaucum)和米瓦罐(Silene conoidea)优势度比,降低牛筋草优势度比;玉米-大豆轮作可增加米瓦罐优势度比。不同耕作方式对偶见种杂草在田间的分布和组成影响不明显。可以看出,新垦沙地农田杂草物种较少,群落组成单一;不同耕作方式对新垦沙地农田杂草物种多样性和群落结构组成有明显影响,进一步深入研究对沙地农田杂草合理防除具有重要的指导意义。

Effects of cultivation regimes on weed community structures in newly reclaimed sandy farmlands

The varieties, quantities, coverage rates and heights of farmland weeds were surveyed and species diversity and richness analyzed in a newly reclaimed sandy farmland located in the margin oasis of the middle reaches of Heihe River Basin, Northwest China. The aim of the study was to evaluate the effects of cultivation regimes on weed community structure characteristics in the basin. A total of 16 weed species from 10 families were identified and recorded. The most common species of weed communities in newly reclaimed sandy farmlands are Chenopodium album, Eleusine indica, Setaria viridis and Amaranthus retroflexus. Weed community compositions are largely influenced by cultivation regimes. Weed species richness, Shannon-Wiener index and Simpson index are lower in conventional cultivation regimes (film mulching, autumn plowing and continuous maize planting). Those could, however, be improved under straw mulching, zero-autumn plowing and maize-soybean rotation treatments. Compared with film mulching, E. indica has a higher dominance ratio while C. album and A. retroflexus have lower dominance ration under straw mulching treatments. Compared with autumn plowing, S. viridis, A. reteroflexus, Silene conoidea and C. glaucum have a higher dominance ratio whereas E. indica has a lower dominance ratio under zero-autumn plowing treatments. Also compared with continuous maize planting, S. conoidea exhibits a higher dominance ratio under maize-soybean rotation regimes. There exist random rare weed species distribution in the field, which are not significantly effected by cultivation regimes. Results further show that weed species is few and weed communities composition is single in a newly reclaimed sandy farmland, and cultivation regimes obviously influence weed species diversity and community structure in reclaimed sandy farmlands. It is recommended to conduct additional research for a non-subjective interpretation of the effects of cultivation regimes on weed growth in order to guide weed control in newly reclaimed sandy farmlands.