Research On The Reproduction Mechanism Of Populus Euphratica Based On The Environmental Factors In The Extremely Arid Region China

As the key part of desert ecosystem in the northwest of China, Ejina Oasis, a fragile region in the arid and extreme arid areas, is facing to the unprecedented disaster, in the process of which the desert riparian forest made up by Populus euphratica Oliv. is worst destroyed. In the recent years, the government has gradually increased the investment to the protection and restoration of Populus euphratica forest, but the results aren’t obviously good due to the least knowledge of its reproduction mechanism. To solve this urgent problem, this paper focused on the reproduction mechanism of Populus euphratica based on the environmental factors and then provided some corresponding key suggestions.Both of water and soil are the most essential factors for the establishment and growth of plants. This study firstly investigated the sexual reproduction of two stages of Populus euphratica, seed germination and seedling growth. We focused on the various screening effects of nine combinations (three moisture gradients×three normal soil types) on seed and seedling of Populus euphratica. With the water content rising (from10%to20%), seeds and seedlings on all the soil substrates showed higher germination rate, germination speed or germination index and survival rate and better growth conditions, respectively. Besides, higher moisture could guarantee seeds to germinate4-8hours earlier and greater germination rate. In the comparison among the soil substrates, seeds and seedlings favored the lower-salinity and richer-nutrient river bank soil, which impelled a4-hour earlier and higher germination peak period and ensured the greatest seedling quality. Therefore, the combination of’20%, river bank soil’was the most suitable condition for P. euphratica seeds and seedlings, which highly consisted with its riparian sexual regeneration phenomenon. Finally, by analyzing the unsteady river flow and river bank status, we concluded that the reason for the failure of P. euphratica sexual reproduction was that the time and quantity of water supply should be adjusted to create more suitable and stable habitat for P. euphratica seeds and seedlings.As to the clonal reproduction of P. euphratica, this paper analyzed the germination and growth of root sucker by three separate experiments of water, salinity and soil types and tested the results by field investigation. When the moisture reached10%, the sucker spots could be produced, and15%water content was the most suitable condition. In the salinity experiment, it showed that lower and middle salinity favored the root suckers and the high (i.e. electric conductivity,1900-2100cm/ds) could inhibit them. Compared with the shrubby meadow soil and the river bank soil, sand soil favored the suckers because of its lower gravity and compactness.