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积雪变化对青藏高原典型高寒生态系统的影响
Alternative TitleEffects of Snow Change on Typical Alpine Ecosystems in Qinghai - Tibet Plateau
肖瑶
Subtype硕士
Thesis Advisor王根绪
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline自然地理
Keyword青藏高原 积雪增加 根功能性状 物候 叶片特征 群落结构
Abstract积雪在青藏高原分布范围广,与气候变化相互作用可显著影响高寒生态系统的结构和功能。为明确积雪变化下植物根系和植物地上-地下耦合特征,探明雪生态效应对不同植被类型的差异性响应格局特征及其可能的内在生物学机制,并考虑到研究区、植被类型或冻土因素对积雪生态效应的影响,本研究选择青藏高原腹地多年冻土区风火山地区的高寒草甸和高寒沼泽草甸,青藏高原东南缘非多年冻土区贡嘎山雅家埂地区的灌草交错带为研究对象,通过雪栅栏的方式人为诱导积雪增加,结合植物地上、地下根系以及土壤变化,来综合分析积雪-植被-土壤之间的耦合变化特征,明晰高寒生态系统结构和功能对积雪变化的差异性响应格局和生物学机制,为冰冻圈生态系统应对未来气候变化的模型估算和区域生态综合管理政策制定提供数据支撑和理论依据。主要研究结论如下:(1) 积雪增加对土壤水热和养分变化的影响雪栅栏诱导积雪的增加可改变土壤温度和水分含量,但不同植被类型和不同土壤深度的变化幅度存在差异。灌草交错带和高寒沼泽草甸土壤温度呈增加趋势,但是只有灌草交错带5 cm深度土壤温度显著增加;然而高寒草甸下三层(20 cm、30 cm和50 cm)土壤温度显著降低。积雪处理下的土壤水分含量在三种植被类型下总体呈增加趋势,但只在多年冻土区的高寒草甸和高寒沼泽草甸变化显著。积雪可增加土壤养分含量,本实验中,高寒草甸和高寒沼泽草甸主要表现在土壤速效磷含量的增加。而贡嘎山灌草交错带土壤养分含量对积雪的增加更加敏感,表现在全碳、有机碳、全磷和表层速效磷的增加。积雪增加导致的土壤含水量变化在多年冻土区(高寒草甸和高寒沼泽草甸)大于非多年冻土区(贡嘎山灌草交错带);积雪增加在非多年冻土区对土壤养分的影响大于多年冻土区,而多年冻土区的高寒草甸和高寒沼泽草甸速效磷变化也相反。(2) 积雪增加对根功能性状的影响贡嘎山灌草交错带根系形态特征比高寒草甸和高寒沼泽草甸对雪栅栏诱导积雪的增加更加敏感。2015年高寒沼泽草甸10-20 cm比根长显著降低;贡嘎山灌草交错带0-10 cm根组织密度显著增加,而10-20 cm根组织密度显著降低。2016年贡嘎山灌草交错带0-10 cm深度总根长、根组织密度和根长密度均显著降低。积雪增加处理对根生物量没有显著影响。积雪增加导致高寒草甸土壤10-20 cm和20-40 cm,高寒沼泽草甸20-40 cm根碳含量显著降低。高寒沼泽草甸10-20 cm和20-40 cm,贡嘎山灌草交错带0-10 cm土壤深度的根系氮含量显著增加。高寒沼泽草甸10-20 cm和20-40 cm,贡嘎山灌草交错带0-10 cm和10-20 cm土壤深度的根系C:N均显著降低。积雪增加对根系形态的影响在非多年冻土区(贡嘎山灌草交错带)大于非多年冻土区(高寒草甸和高寒沼泽草甸)。C、N和C:N在植被类型间变化趋势一致,但非多年冻土区与多年冻土区,多年冻土区下的不同植被类型间存在差异。(3) 积雪增加对植物物候的影响积雪可改变物种的繁殖物候,总体上表现为:推迟开花的峰值时间,并延长开花的持续时间;推迟结果时间,并延长结果的持续时间;加大开花与结果峰值之间的时间间隔。但是积雪增加对繁殖物候的影响存在物种间的差异。各物种受影响的幅度存在差异。(4) 积雪增加对叶片功能性状的影响比叶面积在积雪处理下均没有显著性变化。积雪增加对所有物种C、N含量以及C:N均没有显著影响。高寒草甸小嵩草δ13C值显著降低,而藏嵩草δ15N显著增加。同位素δ13C和δ15N在其他物种中均没有显著变化。同在多年冻土区下的不同植被类型间叶片同位素变化存在差异。(5) 积雪增加对群落结构的影响积雪增加可促进群落高度的增加:2016年高寒草甸、贡嘎山草本群落和贡嘎山灌木群落的群落高度均显著增加。积雪对群落盖度存在年际和植被类型间的差异性影响。2015年和2016年高寒草甸物种丰富度均显著增加。非多年冻土区下植被群落盖度和高度与多年冻土区的高寒草甸变化趋势一致,而物种丰富度变化不同。而多年冻土区的高寒沼泽草甸与没有出现前两种植被类型的高度、盖度和物种丰富度的变化。(6) 积雪增加对土壤-根系-地上特征的综合影响及异同中纬度高海拔地区积雪增加的影响在土壤、根系和植物地上部分存在相互联系,在保持一些相似规律(如土壤温度变化,水分含量增加,根系形态指标减小、C:N减小,群落高度和盖度增加)的同时,也存在一些差异:多年冻土区与非多年冻土区存在差异;同在多年冻土区不同植被类型下存在差异;年际存在差异;物种水平的差异(物候和叶片同位素);本研究中物候结果与北极研究结果的差异。
Other AbstractSnow addition can influence the structure and function of alpine ecosystem. Snow distributes widely in the Qinghai-Tibet Plateau, and interacts with climate change. Considering the influence of study area, vegetation types or permafrost on ecological effect of snow, shrub-grass ecotone, alpine meadow and alpine swamp meadow under snow addition were studied in order to clarify the characteristics of plant root and the interaction between plant underground part and aboveground part, as well as explore the characteristics of different ecological responses of different vegetation types and their potential biological mechanisms. Alpine meadow and alpine swamp meadow were located in the Fenghuoshan Mountain of permafrost region in the hinterland of the Qinghai-Tibet Plateau, and shrub-grass ecotone on Yajiageng Valley, Gongga Mountaion was located in the non-permafrost regions, the southeastern edge of the Qinghai-Tibet Plateau. The relationship among the snow-vegetation-soil was analyzed by combining the above-ground,underground and soil changes by using snow fence. The purpose is to clarify the different response pattern and biological mechanism of the structure and function of the alpine ecosystem to snow addition, and provide the data support and theoretical basis for the model of the frozen ecosystem to cope with the future climate change and the regional ecological management policy formulation. The main conclusions are as follows:(1) The effect of snow addition on soil temprature, soil water content and nutrient changesSnow addition induced by snow fence can change the soil temperature and increase soil water content, but the variation range of different vegetation types and different soil depths was different. Snow addition increased the soil temperature of shrub-grass ecotone and alpine swamp meadow, but only the soil temperature of 5 cm depth increased significantly. However, the soil temperature of alpine meadow decreased significantly at the depth of 20 cm, 30 cm and 50 cm. Soil water content increased under snow addition increased of three vegetation types, but only the sites in permafrost region (alpine meadows and alpine swamp meadow) changed significantly. Snow addition can increase soil nutrient content. The soil nutrient change of alpine meadow and alpine swamp meadow was reflected in soil available phosphorus. The soil nutrient content in the shrub-grass ecotone of Gongga Mountain was more sensitive to the snow addition which was manifested in the increase of total carbon, organic carbon, total phosphorus and surface available phosphorus.Snow addition had greater effect on soil water content in permafrost region (alpine meadow and alpine swamp meadow) than the non-permafrost region (shrub-grass ecotone). While snow addition had greater effect on soil nutrients in the non-permafrost region (shrub-grass ecotone) than the permafrost region (alpine meadow and alpine swamp meadow). The change of available phosphorus of alpine meadow and alpine swamp meadow located in the permafrost region was also opposite.(2) The effect of snow addition on the root functional traitsThe root morphological characteristics of the shrub-grass ecotone in Gongga Mountain were more sensitive than those of alpine meadow and alpine swamp meadow. The specific root length of 10-20 cm in the alpine swamp meadow reduced significantlly in 2015. Root tissue density of 0-10 cm increased significantly in shrub-grass ecoton of Gongga Mountain, and the density of 10-20 cm decreased significantly. In 2016, the total root length, root tissue density and root length density of 0-10 cm depth of the shrub-grass ecotone in Gongga Mountain decreased significantly.Snow addition had no significant effect on root biomassSnow addition resulted in a significant reduction in root carbon content in alpine meadows and alpine swamp meadows. The nitrogen content of root system in alpine meadow and shrub-grass ecotone of Gongga Mountain were significantly increased. The root C;N of the alpine meadow and the shrub-grass ecotone of Gongga Mountains were significantly decreased.Snow addition had greater effect on root morphological characteristics in the non-permafrost region (shrub-grass ecotone) than the permafrost region (alpine meadow and alpine swamp meadow). The changes of C, N and C:N were differenent between permafrost region and non-permafrost region, and also differnet vegetation stypes of permafrost region.(3) The effect of snow addition on plant phenologySnow can change the reproductive phenology of species, as a general manifestation: delay the peak time of flowering and prolong the duration of flowering; postpone seeding time and extend the duration of the seeding; increase the duration between peak flowering and seeding. However, the effect of snow addition on reproductive phenology was different among species. The magnitude of the shifts varied among species.(4) The effect of snow addition on leaf functional traitsThere was no significant change in specific leaf area under snow addition. There was no significant effect on C, N content and C: N in all species. The δ13C value of Kobresia pygmaca decreased significantly, while δ15N of Koeleria tibetica was significantly increased. The isotopes δ13C and δ15N did not change significantly in other species. The change of leaf isotopic was different between vegetation types in the permafrost region.(5)The effect of snow addition on community structureSnow addition can increase the height of community: the community heights of alpine meadow, Gongga Mountain grass community and Gongga Mountain shrub community increased significantly in 2016. The effect of snow on the coverage varied among different years and vegetation types. The species richness of alpine meadows increased significantly in 2015 and 2016.The change tendency of coverage and height of community in the non-permafrost region were consistent with the alpine meadow in the permafrost region, but the species richness varied with each other. While the alpine swamp meadow of the permafrost region did not show changes of coverage, height and species richness.(6) The synthetic effect of snow addition on the soil-root-aboveground characters and the similarities and differencesThe influence of snow addition in the middle latitude and high altitude region on soil, root system and the aboveground plant parts were interrelated. The similar trends included the change of soil temperature, the increase of soil water content, the decrease of root morphological index, the decrease of C: N of root, the the increase of height and coverage of community. There were also some difference between permafrost and non-permafrost region, different vegetation types in permafrost regions, different years; and difference among species (phenology and leaf isotopes).The phenological results in this study was partly different with the results of the studies in the Arctic.
Pages80
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24577
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
肖瑶. 积雪变化对青藏高原典型高寒生态系统的影响[D]. 北京. 中国科学院大学,2017.
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