Comparison of plant species diversity in continuous rice-wheat and rice-fallow systems

To explore the effect of fallow on weed community and species diversity in farm ecosystem, species composition and diversity were investigated in the interior, field bund, and drainage ditch of continuous rice-wheat and rice-fallow systems. The results showed that, 1) 64 species (58 genera belonging to 28 families) were distributed in continuous rice-wheat system with 39.1% perennial plants, while 76 species (32 families belonging to 68 genera) were distributed in rice-fallow system with 52.6% perennial plants; 2) Fallow significantly increased species richness (P=0.021)and Shannon-Wiener diversity index(P=0.006), but the difference of Simpson dominance index and Pielou evenness (P=0.318)index were not significant(P=0.844), between the two systems; 3) The species index in field bund were higher than that in interior and drainage ditch of both systems, which showed the importance of non-crop habitats for maintaining biodiversity, but no significant differences were found between the margin and interior of rice-fallow system; 4) The results of DCA clearly reflected the distribution range of various community types. Almost all rice-wheat communities were separated from rice-fallow communities, and community composition were similar between interior and field bund in the fallow period. These results reveal that fallow can reduce the difference of species composition between crop and non-crop habitats and effectively improve the plant biodiversity level of farm ecosystem.