Knowledge Resource Center for Ecological Environment in Arid Area
| 毛乌素沙地四种关键植物幼苗出土及生长对沙埋和水分的响应 | |
| 其他题名 | Responses of seedling emergence and growth of four key speceis to sand burial and watering regime in Mu Us sandy land |
| 郑明清 | |
| 出版年 | 2008 |
| 学位类型 | 博士 |
| 导师 | 周广胜 |
| 学位授予单位 | 中国科学院植物研究所 |
| 中文摘要 | 飞播是毛乌素沙地植被恢复与重建的重要手段。但此项技术仍存在一些问题，如飞播后成苗率较低等。柠条(Caragana korshinskii)、羊柴(Hedysarum laeve)、籽蒿(Artimisia sphaerocephala)与油蒿(Artimisia ordosica)是毛乌素沙地广泛分布的物种，也是飞播的主要物种。本文以飞播植被恢复技术为突破口，研究沙埋和土壤水分对种子萌发，幼苗出土和生长的影响，探讨幼苗出土和生长对沙生环境的适应对策。对采用合适的物种进行生态工程建设，提高生态工程的稳定性及可持续性具有重要意义。同时，本项研究有助于加深半干旱区植物对沙生环境适应机理的认识。\n以上述4种植物为研究对象，设定7个沙埋深度和9个水分梯度，研究种子萌发和幼苗出土对沙埋和单次供水的响应。设定7个沙埋深度，选择3个沙丘部位，研究沙丘不同部位对植物种子萌发的影响。设定6个沙埋深度、4个水分梯度，研究两种蒿属植物幼苗生长对不同沙埋和供水的响应。得出如下主要结论：\n(1) 对于种子质量相对较大的柠条和羊柴而言，在一次性10-20 mm供水量条件下，幼苗主要在0.5-2 cm埋藏深度之间出土，但在埋藏深度为5 cm时这两个物种仍有少部分幼苗能够出土；对于种子质量相对较轻的油蒿和籽蒿而言，在一次性10-20 mm供水量时，幼苗主要在0.5 cm埋藏深度出土，油蒿和籽蒿幼苗在埋藏深度为1.5和2 cm时不能出苗。沙埋深度为0.5 cm时，4个物种出苗率较高、出苗时间较短、出苗速率较快。\n(2) 实验期内(30天)在一次性供水量分别为5、7.5和7.5mm时，柠条、羊柴和油蒿出土幼苗全部死亡；在一次性供水量高于15-20 mm时，出土幼苗死亡率低于50%；籽蒿在供水量高于10 mm时出土幼苗死亡率低于50%；随供水量的增加4个物种出土幼苗的死亡率降低。\n(3) 结合毛乌素沙地降雨特点与本文实验结果，0.5 cm的沙埋及7.5 mm以上的单次降雨量是上述4种植物自然条件下出苗较高的重要条件。\n(4) 在沙丘顶部，2-7 cm沙埋深度之内各个物种不同沙埋深度的种子萌发率差异不显著。沙丘背风坡中部和底部，4个物种在沙埋深度为1 cm时的种子萌发率均显著高于5、7 cm时的萌发率。当沙埋深度为1-5 cm时，柠条和羊柴种子在坡面不同位置的萌发率均高于20%，且显著高于7 cm沙埋深度时的萌发率。在背风坡底部时，柠条、羊柴、油蒿和籽蒿的种子萌发率达到最大值，分别为45.2±3.27%、48.4±5.21%、20.8±4.63%和22.4±4.83%。4个物种的种子萌发率从沙丘顶部到背风坡中部到底部呈递增趋势，表明背风坡中部和底部的环境条件要比顶部更适合种子萌发。\n(5) 部分沙埋促进幼苗生长。2种蒿属植物幼苗在沙埋深度为0.25、0.5 H时比在0、0.75 H时具有更高的生物量、叶面积、相对生长速率（RGR）和净同化速率（NAR）。在75 mm/月供水量时，油蒿幼苗具有较高的生物量和叶面积，但当供水量达到100 mm/月时其幼苗生长受到抑制。油蒿幼苗在遭遇较深（0.5、0.75 H）沙埋时的根冠比要显著高于未沙埋幼苗的根冠比；籽蒿幼苗根冠比在不同沙埋条件下没有显著变化。籽蒿幼苗在50 mm供水量时具有较高的RGR。油蒿幼苗在75 mm供水量时具有较高的RGR和NAR。 |
| 英文摘要 | Mu Us sandy land has become one of the central areas of desertification in North China. Over the years it has been proved that water and sand movements are likely the most severe stress factors limiting successful vegetation establishment and restoration in this area. Aerial seeding has long been regarded as a successful and quick measure for vegetation rehabilitation in sand lands, but seedling emergence of dominant psammophyte species inhabiting in Mu Us sandy land including Caragana korshinskii, Hedysarum laeve, Artemisia ordosica and Artemisia sphaerocephala is low. Target at improving techniques of aerial seeding for vegetation restoration, we tested the seed germination, seedling emergence, survival and growth behavior of the four above-mentioned psammophytes to sand burial depth, burial time, different parts of the dune, single-watering events and different water regime. Results may help in better understanding the performance of these species on restoration sites. Based on the filed experiment on effects of sand burial and watering regime on seed germination, seedling emergence and growth, the adaptation of four key species to sandy environment was discussed, and main results included: \n(1) Two species (C. korshinskii and H. leave) with relatively big seeds emerged mostly at 0.5-2 cm sowing depth, under 10-20 mm one time water supply regime, and there are also a little seeds of these two species emerged at 5 cm sowing depth; another two species (A. ordosica and A. sphaerocephala) with relatively small seeds emerged well only at 0.5 cm sowing depth, under 10-20 mm one time water supply regime, A. ordosica and A. sphaerocephala can not emerge at 1.5 and 2 cm, respectively. In general, a 0.5 cm sowing depth resulted in the highest seedling emergence and emergence rate. \n(2) After 30 days, all emerged seedlings of C. korshinskii, H. leave and A. ordosica died under 5, 7.5 and 7.5 mm one time water supply regime, respectively, and the seedlings mortality of four species was lower than 50% in most treatments when the one time water supply regime is higher than 10 mm. As the increase in water supply, the mortality of emerged seedlings of these four species was decreased.\n(3) Based on precipitation characteristics of the Mu Us sandy land and our experiment results, 0.5 cm sowing depth and one time water supply regime more than 7.5 mm is the important conditions for seedling emergence and maintaining in field of all 4 species.\n(4) Germination percentages of the four species showed a tendency to increase from the top of the dune to the middle of the leeward slope and then to the bottom. At the middle and bottom positions on the leeward slope, germination percentages of the four species at 1 cm was higher than they were at 5 and 7 cm. Germination percentages of C. korshinskii and H. laeve at 1 to 5 cm was >20%, which were higher than those at 7 cm. Maximum germination percentages of C. korshinskii, H. leave, A. ordosica and A. sphaerocephala at the bottom of leeward slope were 45.2±3.27%, 48.4±5.21%, 20.8±4.63% and 22.4±4.83%, respectively. \n(5) Both of two Artimisia seedlings buried at 0.25 and 0.5 H showed a higher biomass, leaf area, RGR and NAR than they were at 0 and 0.75 H sand burial. For A. ordosica, the highest biomass and leaf area were achieved under 75 mm water regime, but inhibited by 100 mm water regime. For A. sphearocephala, 50 mm water regime had a higher biomass, leaf area and RGR compared with that under 75, 100 mm water regime. A. ordosica invested more resources in root mass than that of A. sphearocephala. Seedlings of A. ordosica at relative deeper depth (0.5, 0.75H) exhibited a significantly higher root/shoot ratio than unburied seedlings. |
| 中文关键词 | 土地荒漠化 ; 飞播 ; 毛乌素沙地 ; 单次供水 ; 沙埋 ; 种子萌发 ; 幼苗出土 ; 幼苗生长 |
| 英文关键词 | Desertification air-seeding Mu Us sandy land single-watering events sand burial seed germination see |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286715 |
| 推荐引用方式 GB/T 7714 | 郑明清. 毛乌素沙地四种关键植物幼苗出土及生长对沙埋和水分的响应[D]. 中国科学院植物研究所,2008. |
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