Appropriate time of plant- resources relationship regulation
After planting weather planting or sowing, as plant grow, the available resources reduced. For example, the suitable sowing rate of Caragana young forest is 1.5kg/100m2, and the suitable density is 6500 plants / 100m2 in the semiarid loess hilly region. As the caragana plant grows, soil water content in the maximal infiltration depth of 290 cm reduces, and soil desiccation has been emerged in perennial non-native shrubland. When caragana is at 5-years old on Jun.15, 2006, soil water resources in the maximal infiltration depth of 290 cm are smaller than 222.8mm, showing that the plant-water relation enters the critical period of plant-water relationship regulation and regulation of plant water relationship should be considered, see figure 5.