Mean cover of dominant plant species and functional groups and several community traits in adjacent ex-arable and never-tilled fields, Methow Valley, Washington, USA.

Cover values within fields (replicate plots) and among years were averaged prior to calculations so that values represent averages and standard errors associated with the 25 fields.在开展计算前，先对各重复样地（replicate plots）内部以及不同年份间的盖度值进行平均化处理，以使最终结果为与这25个样地对应的平均值及标准误。