沙埋与供水对毛乌素沙地两种重要沙生植物幼苗生长的影响

沙埋与水分是影响毛乌素沙地植物存活、生长的关键因子。通过沙埋与供水的野外控制实验,研究了毛乌素沙地重要物种柠条(Caragana korshinskii)与羊柴(Hedysarum laeve)幼苗存活及生长对沙埋和供水的反应。结果表明:适量的沙埋(0.25H-0.50H沙埋,H为苗高)与供水(柠条50mm/月,羊柴75mm/月)可以促进幼苗生长,过量的沙埋与供水则会抑制生长甚至导致幼苗死亡。柠条幼苗在50mm/月供水,0.25H、0.50H沙埋,羊柴幼苗在75mm/月供水,0.25H、0.50H沙埋下具有较高的相对生长速率和净同化速率;幼苗在1.0H和1.25H沙埋下全部死亡。供水量较小、沙埋较浅时,两种植物根冠比均较高;当供水量最大时,柠条幼苗根冠比在沙埋最深和没有沙埋时较大,而羊柴幼苗根冠比仍在没有沙埋时最高。

Effects of sand burial and water supply on seedlings growth of two dominant psammophytes in Mu Us sandland

Sand burial and water supply are the key ecological factors that affect plant survival and growth in Mu Us sandland. Caragana korshinskii and Hedysarum laeve are two dominant semi-shrub species distributed in this area. Experiments were conducted under controlled conditions to investigate the effects of sand burial and water supply on seedlings survival and growth of these two species. The results showed that appropriate sand burial (0.25H-0.50 H burial, H is the hight of seedling) and water supply (50 mm/month for C. korshinskii, 75 mm/month for H. laeve) could promote seedling growth of two species, whereas over sand burial could inhibit seedling growth, and even resulted in seedlings death. Seedlings of C. Korshinskii had a higher RGR and NAR under 50 mm water supply and 0.25H, 0.50 H sand burial regimes, while H. laeve had higher RGR and NAR under 75 mm water supply and 0.25H, 0.50 H sand burial regime. However, all seedlings died under 1.0 and 1.25 H sand burial regimes. The ratio of root/shoot was high when water supply was low and sand burial was shallow for two species; when water supply was high, the ratio of root/shoot was high for C. korshinskii under the deepest and the shallowest sand burial regime, while it was high under the shallowest sand burial for H. laeve.