The yearlyvariation of soil and water is obviously characterized by stages, which is favourable for wheat growth.
土壤水分周年变化有明显的阶段性，有利于小麦生长，旱塬小麦耗水系数高，水分利用效率低。
2
This report describes the principles and methods for grass production classification and yearlyvariation using LANDSAT TM data.
本文介绍用陆地卫星TM 资料作达里诺尔地区草场牧草产量分级图及两年产草量变化分级图的原理与方法。
3
From population level to functional group level, and then to community level, the yearly-variation of aboveground biomass minimizes gradually and stability increases.