Soil Water in Planted Haloxylon ammodendron Shrubland of Different Age outside Minqin Oasis

Soil water contents at different depths(20 cm,30 cm,50 cm,100 cm,150 cm and 200 cm) were examined in planted Haloxylon ammodendron shrubland of different stand age(2-year,5-year,10-year,20-year and 30-year) outside Minqin oasis from June to September,2009.The results showed that soil water contents in H.ammodendron of different stand age were related to precipitation and soil depth.Soil water content at surface layer was affected by natural rainfall.In September,soil water contents at 20 cm and 30 cm in H.ammodendron of different stand age were significantly higher than that in other three months because of 25.8 mm rainfall in late August.Soil water content was relatively stable in deeper depths(50 cm) and it can be used by H.ammodendron when surface soil water was absent in period with lower rainfall.In July and August,soil water content in planted 5-year H.ammodendron shrubland was the lowest(1%) because the plant density was too high for 5-year planted H.ammodendron shrubland,and the consumption amount of soil water was the highest;therefore,planted shrubland may need to be lumbered to decrease plant number to keep its stability.