| 引用本文: | 张国帅，郑勤莹，克依木▪买尔当，李宗善，范泽鑫，王晓春.2020.滇西北地区高寒草甸多年生草本植物年轮特征分析[J].地球环境学报,11(6): |
| ZHANG Guoshuai, ZHENG Qinying, KEYIMU Maierdang, LI Zongshan, FAN Zexin, WANG Xiaochun.2020.Growth ring pattern of perennial herbaceous species in alpine meadow in northwestern Yunnan, China[J].Journal of Earth Environment,11(6): |
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| 摘要: |
| 近年来的研究表明，年轮在多年生草本植物根部广泛分布，并且每年都会形成新的年轮。然而，目前对于滇西北高寒草甸草本植物年轮的存在及年轮特征的研究甚少，草本植物的年龄也基本未知。本文以滇西北高寒草甸的15种多年生草本植物为研究对象，分析了主根次生木质部的年轮特征，测量了年轮宽度及导管参数。结果表明：11种植物具有清晰的年轮结构，60%的植物具有清晰或相对清晰的年轮边界。这些草本植物的生长期是从2012到2017年，平均年龄为3.8岁（2—6岁）。该地区的物种生活史缩短的主要原因可能是高山林线以上的环境胁迫导致的。在草本植物生长前期，主营养生长，草本植物的径向生长与气候之间存在较为密切的关系，气候变化对高山草甸植被的影响直接作用于草本植物的生理生态过程中。高海拔地区光照充足，植物具有较强的光合作用，使得多年生草本植物的生长速率和导水效率随年龄增长呈上升趋势，这也可能是对全球变暖的积极反馈机制。随着年龄的增加，草本植物为增加生存和繁殖成功的机率，会采取一系列自我保护措施，改变生活史策略，减少导管数量，同时减小导管的大小。 |
| 关键词: 多年生草本物种 解剖结构和规律 轮宽 导管 年龄分布 |
| DOI：10.7515/JEE192058 |
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| 基金项目:国家重点研发计划项目（2016YFC0502105）；第二次青藏高原科考项目（2019QZKK0502）；国家自然科学基金项目（31861133007） |
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| Growth ring pattern of perennial herbaceous species in alpine meadow in northwestern Yunnan, China |
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ZHANG Guoshuai, ZHENG Qinying, KEYIMU Maierdang, LI Zongshan, FAN Zexin, WANG Xiaochun
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1. State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
2. College of Forestry, Northeast Forestry University, Harbin 150040, China
3. Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Xishuangbanna 666303, China
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| Abstract: |
| Background, aim, and scope Recent studies have indicated that annual growth rings are widespread in the roots of herbaceous species and formed annually. However, little is known about the presence and characteristics of annual growth rings in alpine meadow of northwestern Yunnan, China, the age of herbaceous species is also largely unknown. Materials and methods We cut off the main roots approximately 5—10 cm beneath the ground surface from each species (3—5 individuals for per species) that were growing well. The root samples were put in sealing bags in the field and stored in 75% alcohol after washing the samples clean. In the laboratory, we cut cross-section (10—15 μm thickness) from the proximal end of the root samples to avoid missing annual rings with pulley section cutter, and stained the paraffin sections with 1% safranine water solution and 0.5% fast green ethanol solution. Finally, we measured the ring width and vessel parameters with WinCELL automatically. Results Eleven species showed annual growth ring structures and 60% of species showed clear or relatively clear demarcated annual ring boundaries. The period spanned 2012—2017 with an average age of 3.8 years (2—6 years old). Meanwhile, the growth rates and hydraulic conductivity indicated increasing tendency with age. Whereas, the vessel size indicated decreasing tendency over the years. Discussion The annual growth ring structure were significantly lower than others, which might be due to a relatively low number of species sampled in our study area. Meanwhile, perennial herbaceous species were relatively young, resource stress above alpine treeline might contribute to shorter life history strategies. Finally, we analyzed the changing trend of ring width and the structure of vessels. The main reason for the shortened life history of species in this area may be caused by environmental stress above the alpine timberline. In the early stage of herbaceous plant growth, it is primarily the stage of vegetative growth. There is a close relationship between the radial growth of herbaceous plants and climates, and the impact of climates change on alpine meadow vegetation directly affects the physiological and ecological processes of herbaceous plants. High altitude areas own plenty of light and plants have strong photosynthesis, so that the growth rate and water transfer efficiency of perennial herbs increase with age, which may also be a positive feedback mechanism for global warming. With the increase of age, herbaceous plants will adopt a series of self-protection measures to increase the probability of survival and reproduction success. They will avoid this injury by transforming their life history strategies, reducing the number of vessels and reducing the size of the vessels. Conclusions We found that the true annual growth rings occurred in the secondary root xylem of the perennial herbaceous species in northwestern Yunnan, and the growth ring showed fluctuations between species. This is a trade-off performance for drought stress conditions caused by climate warming, while increasing the probability of reproduction to reduce the risk. Our results provide further evidence for the sensitive and rapid response of radial increment growth in roots of perennial herbaceous species in northwestern Yunnan. Recommendations and perspective The authors predict that there was similar result elsewhere in an alpine meadow region and set out to do further statistical analysis combining with meteorological factors. |
| Key words: perennial herbaceous species anatomical structure and pattern ring width vessel age distribution |
