科尔沁沙地植被演替的抗逆性特征

Characters of Resisting Adverse Environment in Vegetation Evolution in Horqin Sandland

在科尔沁不同类型沙地上选择了几种优势植物，通过自然脱水、高温处理过程中抗逆生理指标的测定和叶形态观测，研究了它们的抗逆方式和生理抗逆性差异与科尔沁沙地植被演潜规律的关系。结果表明，在自然脱水、高温处理中流动沙地上的沙米和欧亚旋覆花叶片迅速脱水死亡，而细胞内膜脂过氧化作用强烈引起细胞膜严重受损是其死亡的主要原因；半流动沙地上的差不嘎蒿在胁迫过程中叶变黄，但在复水后能恢复生长，这与其胁迫过程中游离脯氨酸含量增加维持叶渗透压减少水分过度丧失有关，半固定沙地芦苇在胁迫过程中叶干枯死亡，这与其细胞保护酶反应迟钝，积累的氧自由基引起膜脂过氧化作用伤害了膜系统有关；固定沙地上的狗尾草、白草在胁迫过程中萎蔫，复水后恢复生长，生理变化表现为保护酶对胁迫反应快，可溶性糖、游离脯氨酸含量增加，是一真正生理抗逆植物。在生境从流动沙地向固定沙地演变过程中，植物抗逆性在植被演替序列中起重要作用，其演替规律为：①从躲避干旱向生理抗旱发展，其中流动沙地上的沙米、欧亚旋覆花以种子形式躲避逆境，固定沙地的白草以生理抗旱为主；②从抗风沙型向抗旱性发展，如流动半流动沙地的差不嘎蒿具有抗沙埋、抗旱特性，固定沙地上的白草的抗沙埋性差，抗旱性较强；③生?

The different ways and different mechanisms in physiology of several desert plants resisting to adverse environment were investigated under air dehydrate, high temperature conditions. Agriophllum squarrosum, Convolvulus chinensis grown on shifting sand dune were typical kinds of avoiding drought due to death caused by water lost in their leaves rapidly, and very strongly lipid peroxidation resulting in cell membrane injury under two stresses was the reason; Artemisia halondendron grown on semi shifting sand dune was of higher ability to resist drought depending on its osmoregulation; Pennisetum centrasiaticum and Setaria viridis grown on fixed sand dune are true drought resistant plants relying on changes in physiological metabolism resulting in very quickly response action of protective enzyme to bad condition, and on accumulation in proline, protein, soluble contents. The results showed that the ability of resistance to stress condition in the desert plants played a very important role in rank of vegetation succession of Horqin sandland on development from the shifting to the fixed dune, in which the evolution law was: ① development from avoiding drought to resisting drought; ② development from resisting wind sand to tolerating drought; ③ development in the way of survive from mono way to multi way; ④ development from resistance to high temperature, wind sand and drought to only tolerance to drought.