Abstract: Aiming at the poor regeneration status of artificial Haloxylon ammodendron plantations in Minqin oasis and from the viewpoint of the necessary conditions for their natural regeneration, a comparative study was made on the necessary ecological conditions for the seed germination, seedling survival, and growth of H. ammodendron at different sites, with the limiting factors for the regeneration of artificial H. ammodendron plantations in the oasis analyzed. The annual mean precipitation in the oasis from 1971-2002 was 116 mm, being suitable for H. ammodendron growth, but the seasonal variation of the precipitation affected the natural regeneration of H. ammodendron. Due to the drought climate in winter and spring, soil moisture had a long term deficit before rainy season, and accordingly, the seed germination and seedling emergence rates of H. ammodendron were low. There were great differences in the growth and seed setting of H. ammodendron among different sites, and thus, site type was another factor affecting the natural regeneration of artificial H. ammodendron plantations.

Key words: Constructed wetland, Wastewater treatment, Technical parameter, Ecological method