Scheme of bund, terrace, and field dimensions. Upland (a) and lowland (b) rice fields. Samples of vegetation were taken in a period from October 2011 through to June 2012, i.e. including two cultivation seasons October–December and May–June. The weed vegetation was surveyed in each of the six paddy field sites on a regular grid of sample plots. Each site comprised 33 plots of paddy fields, 20 m2 in size, and 33 plots of bunds, 10 m2 in size. Total vascular plant species composition was determined per plot.