KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 新疆野苹果退化植株个体的水力结构及水分利用特征 | |
| Alternative Title | Hydraulic architecture and water use characteristics of degraded plants of Malus sieversii |
| 孙逸翔 | |
| Subtype | 硕士 |
| Thesis Advisor | 张元明 ; 张静 |
| 2020-09-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 工程硕士 |
| Keyword | 退化野果林 新疆野苹果 植物水力结构 栓塞脆弱性 树干液流 degraded wild fruit forest Malus sieversii hydraulic structure embolism vulnerability sap flow |
| Abstract | 天山野果林是我国特殊的阔叶森林生态系统类型，其中以新疆野苹果（Malus sieversii）为主要建群种。近年来，受人类活动、病虫害和气候变化等的影响，天山野果林生态系统出现严重退化，其中以新疆伊犁地区新源县的新疆野苹果林尤为严重，出现成片、大量衰败和死亡的现象。深入了解天山退化野果林中新疆野苹果植株的死亡机理，对天山野果林的抢救性保护具有重要意义。因此，本研究以伊犁河谷退化野果林为研究区，选取了3种生长势新疆野苹果（以枯枝率表示），分别为Ⅰ级（<20%）、Ⅱ级（40%~60%）和Ⅲ级（>80%），分别从枝条木质部解剖特征和叶片性状，水力结构特征的差异以及水分运输有效性和安全性，树干液流和水分利用效率等三个方面开展了系统性的研究，以期为揭示新疆野苹果植株死亡提供重要数据参考。主要获得以下研究结果：1.不同生长势新疆野苹果植株木质部解剖结构存在显著差异，生长势较差（III级）植株的栓塞更为严重。对比不同生长势植株的木质部解剖结构及其季节动态，结果表明生长势较差（III级）植株的水力直径D95、Dh显著高于生长势良好（I级）植株，这意味着植株的导管更容易引发栓塞。而随着季节的变化，脆弱性指数Vx也不断增大，表明新疆野苹果的木质部水分运输结构很容易遭到破坏，其栓塞脆弱性也越高。而不同生长势新疆野苹果的叶片性状无显著差异。2.通过对比分析不同生长势植株的水力结构参数可知，生长势较差（III级）植株的水分传导效率、栓塞脆弱性显著低于生长势良好（I级）植株，栓塞程度显著高于后者。对新疆野苹果植株的水分传导效率和水力安全特征的相关性分析表明，二者间存在负相关关系。这证实了新疆野苹果的水力结构变化确实伴随着新疆野果林的衰退过程，呈现出生长势较差（III级）植株水分传输更为受限，木质部导管的栓塞化程度更高，抵抗气穴化栓塞的能力更差，面临水力失衡的威胁更大。3.由新疆野苹果的植株树干液流和水分利用效率的对比研究发现，生长势良好的植株E比生长势较差植株A的液流更微弱，水分利用效率更低的现象。生长势良好的植株日均液流累积量最大，退化严重的植株液流累积量最小。而采用偏相关分析得出影响树干液流的环境因子作用大小依次为：土壤温度 >水汽压亏缺 > 风向> 空气相对湿度 > 空气温度 > 风速。生长势较差的新疆野苹果植株的水分利用效率也最低。由此推断，新疆野苹果植株的退化死亡与水力受限有关。综上所述，新疆野苹果在退化衰败的过程中，确实存在着水分传输失败的现象。这是由新疆野苹果自身水力结构特征和水分传输中“低安全，低效率”的现象所决定的。而伴随着其水分传输的失败，新疆野苹果植株的树干液流和水分利用效率也显著降低，使其面临水力失衡的威胁更为严重。 |
| Other Abstract | The wild fruit forest in Tianshan Mountain is a special broad-leaved forest ecosystem type in China, among which Malus sieversii is the main dominant species. In recent years, the ecosystem of wild fruit forest in Tianshan Mountain has been seriously degraded due to human activities, plants diseases and pests, especially in Xinyuan County, Yili of Xinjiang. There is great significance to understand the death mechanism of M. sieversii in degraded wild fruit forest of Tianshan Mountain. Therefore, in this study, the degraded wild fruit forest in Ili valley was selected as the research area. Three kinds of growth potential of the individual M. sieversii (represented by dead branch rate) were selected, which were Class I (< 20% alive branches in total), Class II (40% ~ 60% alive branches in total) and Class III (> 80% alive branches in total), In order to provide important data reference for revealing the death mechanisms of M. sieversii, systematic research was carried out from three aspects: a. anatomical characteristics of xylem and characteristics of branches and leaves; b. differences in hydraulic architecture characteristics and water transport efficiency and safety; c. sap flow and water use efficiency of trunk. The main results are as follows:1. There were significant differences in xylem anatomical structure of M. sieversii branches with different growth potential, and the embolism was more serious in the plants with poor growth potential. The results showed that the hydraulic diameter D95 and Dh of Class III were significantly higher than those of Class I, which indicated that the vessels of Class III were more likely to cause embolism. With the change of seasons, the vulnerability index Vx also increased, which indicated that the xylem architecture of M. sieversii was easy to be damaged, and its embolism vulnerability was higher. However, there was no significant difference in leaf characteristics among different growth potential.2. By comparing and analyzing the hydraulic architecture parameters of plants with different classes, it was found that the water conductivity efficiency and degree of embolism of Class III was significantly lower than that of Class I. The embolism vulnerability also showed that Class III were significantly higher than Class I plants. The correlation analysis showed that there was negative correlation between water transfer efficiency and hydraulic safety characteristics of M. sieversii. It is confirmed that the change of hydraulic architecture of M. sieversii is closely related to the decline process of wild fruit forest in Xinjiang. The xylem vessels of d Class III were more embolized, and their resistance to cavitation embolism was weaker, and the threat of water imbalance was greater. The water use efficiency of M. sieversii is not suitable for plant growth and development and resistance to environmental changes.3.The sap flow and water use efficiency (WUE) of M. sieversii showed that sap flow of Class E was weaker than that of Class A, and water use efficiency was lower. The results showed that daily average sap flow accumulation of theM. sieversii was the largest, and that of the seriously degraded Class E was the smallest. The partial correlation analysis showed that the order of environmental factors affecting sap flow was Ts > VPD > WD > RH > Ta > Ws. The water use efficiency of M. sieversii with high dead branch rate was also the lowest.In conclusion, the phenomenon of hydraulic failure does exist in the process of degradation and decline of M. sieversii. It is likely determined by the hydraulic architecture characteristics of M. sieversii and its water use strategy. With the failure of water transformation, sap flow and water use efficiency of M. sieversii were also significantly reduced, which made the threat of water imbalance more serious. |
| Subject Area | 生物工程 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15447 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 孙逸翔. 新疆野苹果退化植株个体的水力结构及水分利用特征[D]. 北京. 中国科学院大学,2020. |
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