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沙埋是沙地植物生长和分布的重要选择压力之一,也是影响植物种子萌发、幼苗出土和幼苗存活的关键因素。选择梭梭典型自然生境,模拟梭梭种子自然埋藏深度状况,研究了0、0.5、1.0、2.0、3.0cm 5种沙埋深度对其出苗率及幼苗生长的影响。结果表明:梭梭种子出苗率随埋深增加呈先增加后减小趋势,沙埋深度为0cm时出苗率为4.2%,沙埋深度为0.5、1.0、2.0cm时,出苗率分别为31.9%、14.7%和0.9%,沙埋深度为3.0cm时无出苗。出苗早期,幼苗死亡率均较高,达到平均80.7%;其后,死亡率下降,且2.0cm埋深幼苗死亡率显著高于其它处理,直至幼苗全部死亡。埋深对幼苗生长动态的影响主要表现在幼苗生长早期,0.5cm埋深幼苗的地上、地下部分生长以及根冠比均大于0cm和1.0cm埋深;随着时间的推移,差异逐渐减小。表明0.5cm埋深是梭梭种子萌发和幼苗生长的最佳深度。综上,中度沙埋在一定程度上可以促进梭梭种子的萌发出土与幼苗的早期生长,而重度沙埋抑制幼苗的生长,甚至导致幼苗的死亡。
Sand burial is one of the most important pressures for the growth and distribution of sand plants. It is also a key factor that affects the seed germination, seedling emergence and seedling survival. The typical natural habitats of Haloxylon ammodendron were selected to simulate the natural burial depth of Haloxylon ammodendron seedlings. The effects of five kinds of sand burial depths of 0, 0.5, 1.0, 2.0 and 3.0 cm on their germination rate and seedling growth were studied. The results showed that the seed germination rate of Haloxylon ammodendron increased firstly and then decreased with the increase of burial depth. The seedling emergence rate was 4.2% when the sand burial depth was 0cm, and the seedling rate was 31.9% when the sand burial depth was 0.5, 1.0, , 14.7% and 0.9%, respectively, when the sand burial depth is 3.0cm. Early seedling stage, seedling mortality were higher, reaching an average of 80.7%; thereafter, the mortality decreased, and 2.0cm seedling mortality was significantly higher than other treatments until all the seedlings died. The effects of burial depth on the seedling growth dynamics were mainly manifested in the early seedling growth. The seedling growth at 0.5 cm depth and root / canopy depth were all greater than 0 cm and 1.0 cm depth, and the differences gradually decreased with the passage of time. It shows that the depth of 0.5 cm is the best depth for seed germination and seedling growth of Haloxylon ammodendron. To sum up, moderate sand burial can promote the germination of Haloxylon ammodendron seed germination and seedling early growth, while severe sand buried seedling growth inhibition, and even lead to the death of seedlings.