免费文献传递   相关文献

EFFECT OF INSERTING CORNSTALK IN BARE ALKALI-SALINE PATCHES ON SURVIVAL RATE OF CHLORIS VIRGATA AND SUAEDA CORNICULATA

扦插玉米秸秆对光碱斑地虎尾草和角碱蓬存活率的影响


通过补播植物种子和扦插玉米秸秆,研究自然状况下虎尾草(Chloris virgata)、角碱蓬(Suaeda corniculata)在松嫩草地次生光碱斑的生长状况;并对次生光碱斑自然恢复进程缓慢的原因、生态恢复模式进行了探讨。结果表明:角碱蓬能直接在次生光碱斑上生长,存活率为61.2%±16.5%;虎尾草很难直接在次生光碱斑上生长,存活率仅为5.7%±6.1%,且虎尾草不能繁殖;扦插玉米秸秆极显著地提高了角碱蓬和虎尾草的存活率,存活率分别为74.8%±18.4%、43.1%±20.8%,并保证植物顺利繁殖,为后续的自然演替提供了必备的种源。由于次生光碱斑土壤种子库极小,耐盐碱植物如角碱蓬可直接在光碱斑上生长,因此,除了可溶性盐离子含量过高外,我们提出土壤繁殖体(包括种子和其它繁殖体)极度缺乏也是松嫩草地次生光碱斑自然恢复进程缓慢的重要原因。最后,根据松嫩草地次生光碱斑的土壤理化性质季节变化、当地气候特征和物种资源,把生态学原理与生态工程有机地结合,提出了加快松嫩草地次生光碱斑恢复进程的生态恢复模式。

The Song-nen grassland in China, where Leymus chinensis is the dominant plant, ordinarily belongs to meadow grassland, but now there exists a mass of degraded alkali-saline grassland, with secondary bare alkali-saline patches in a regressive succession, caused by irrational exploitation in past years. It is an imperative and difficult task for scientists and grassland managers to improve or ameliorate these secondary bare alkali-saline patches. There have been extensive studies of the eco-physiological properties of many salt-tolerant plants and the property of soil in the Song-nen grassland. Many scientists and managers consider that the too high content of soluble saline ion in soil is the dominant cause, which made the natural restoration process of secondary bare alkali-saline patches so slow, and have brought forward some effective measures to improve them. However, relatively little is known about the survival rate of some salt-tolerant plants in secondary bare alkali-saline patches under natural conditions. It is a very important factor to the improvement of these bare patches and will to some extent influence the improving effect in practice. So, determining the survival rate of these salt-tolerant plants in natural conditions will help to find an economic and operable way to restore these secondary alkali-saline bare patches. We have investigated the growing dynamics of two salt-tolerant plants (Suaeda corniculata and Chloris virgata) in secondary bare alkali-saline patches in natural conditions through seeding experiments. Moreover, we have also inspected whether some simple experimental treatments can enhance the survival rate of plants in natural conditions through inserting cornstalks in secondary bare alkali-saline patches and seeding. Finally, based on our results and previous work, we have discussed the potential causes, which made their natural restoration process so slow in natural conditions, and ways of optimizing ecological restoration patterns. The results show that Suaeda corniculata is able to grow in the secondary bare alkali-saline patches in natural condition without any auxiliary utilities, and its ultimate survival rate arrives at 61.2%±16.5% in fall; the survival rate of Chloris virgata is very low, and its ultimate survival rate is only 5.7%±6.1%. The mortality rate of the two plants is comparably high in their initial growth period. The treatment of inserting cornstalks significantly enhances the survival rate of Suaeda corniculata and Chloris virgata, and their ultimate survival rates are 74.8%±18.4% ant 43.1%±20.8% respectively. More importantly, they both can reproduce successfully and provide the necessary seeds for subsequent natural succession in these bare patches. The soil seed bank is the template of plant restoration and influences the restoration speed and direction on these secondary bare alkali-saline patches. Natural restoration should be accelerated if there exist substantive seeds of salt-tolerant plants, such as seeds of Suaeda corniculata. Therefore, lack of propagulum in soil (including seeds and other propagulum) should be another important restricting factor, besides the too high content of soluble saline ion in soil, which made their natural restoration process so slow in natural conditions. The experiment shows that it is possible to boost the survival rate of these salt-tolerant plants in secondary bare alkali-saline patches in natural condition, if we take some effective measures. Then, based on these properties of the secondary bare alkali-saline patches, we have put forward a new ecological restoration pattern to accelerate their natural restoration, i.e., rationally integrating the ecological theories into ecological engineering and making the best of local seed resources and local specific climate to improve secondary bare alkali-saline patches. Restoration of these secondary bare alkali-saline patches looks promising, especially where the area of these secondary bare patches is relatively small and their distribution is patchy in Song-nen grassland.