IMHE OpenIR  > 山地表生过程与生态调控重点实验室
模拟增温对青藏高原多年冻土区高寒草甸的影响
Alternative TitleEffects of artificial warming on alpine meadow in the permafrost region of Qinghai - Tibet Plateau
彭阿辉
Subtype硕士
Thesis Advisor杨燕
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline自然地理
Keyword模拟增温 群落结构 功能性状 高寒草甸 青藏高原
Abstract青藏高原被称为“世界屋脊”,其复杂的地形环境和高海拔,形成了该区独特的气候,使其对全球气候变化尤为敏感。过去45年间青藏高原多年冻土区气温增加明显,气候变暖加速青藏高原多年冻土融化,可能对全球变化产生重要的反馈作用。为揭示多年冻土区草地生态系统对气候变暖的响应机制,本研究以青藏高原风火山多年冻土区典型小嵩草高寒草甸和藏嵩草高寒沼泽草甸植物群落及其主要物种为研究对象,采用 OTCs模拟气温增温研究两种草甸生态系统群落结构、地下生产力、叶片及根系功能性状等对气候变暖的生物学和生态学机制,为完善冻土生态系统碳循环的动态平衡机制提供可靠的数据支持。 1、OTCs的增温效果OTCs模拟增温的效果明显,增温使高寒草甸和沼泽草甸生长季空气温度分别提高了2.52℃、2.95℃。增温使高寒草甸土壤 5 cm 含水量降低了3.45%,使土壤20、40 cm土层生长季平均含水量分别增加4.1%和7.31%。增温分别增加了沼泽草甸5、20、40cm土壤含水量5.26%、3.54%和0.93%。2、增温对群落结构的影响增温对多年冻土区两种草甸的物种多样性没有显著影响。增温没有显著改变两种草甸物种丰富度、香浓维纳指数和辛普森指数。高寒草甸群落高度逐年增加,沼泽草甸群落高度逐年下降,且两种草甸OTCs的群落高度均高于对照。增温显著增加了高寒草甸杂草功能群的盖度。3、增温对优势物种叶片功能性状的影响增温增加了高寒草甸垂穗披碱草和沼泽草甸粗喙苔草的比叶面积;增温显著提高了沼泽草甸藏嵩草的δ13C值和水分利用效率,而显著降低了两种草甸中其他优势物种的叶片δ13C 值和水分利用效率。增温显著改变了高寒草甸小嵩草和粗喙苔草的δ15N值,对其他物种没有影响。增温对高寒草甸物种C含量没有显著影响,而显著改变了沼泽草甸物种的碳含量。增温显著减低了高寒草甸物种N含量,而对沼泽草甸物种N含量没有显著影响。增温显著降低了小嵩草的P含量。增温显著增加了高寒草甸物种的C/N比,提高了高寒草甸物种的氮素利用效率,而对沼泽草甸物种的C/N比没有显著影响。增温显著增加了小嵩草的C/P比,提高了其对磷素的利用效率。4、增温对地下生产力及根系功能性状的影响模拟增温显著增加了高寒草甸0~20cm的地下生物量,对沼泽草甸0~20cm的生物量没有显著影响;表明高寒草甸植物地下生产力对气候变暖响应更强烈。增温显著增加了高寒草甸0~10cm根系的根组织密度,显著增加了10~20 cm根系的根组织密度、总根长和总表面积。增温显著增加了沼泽草甸10~20cm根系的比根长,对其他指标没有显著影响。增温显著降低了高寒草甸根系C含量;显著提高了沼泽草甸根系C含量,而对两种草甸根系N含量没有显著影响,表明相对于根系N含量,根系C含量对增温更敏感。
Other AbstractAs the third polar in the world, the Qinghai-Tibet Plateau has a unique environment because of the high altitude and complex topography, which is very sensitive to climate change. The temperature had increased during the last 45 years in the permafrost region of Qinghai-Tibet Plateau. Climate warming could accelerate the permafrost thaw, creating a positive feedback to global warming. To understand the warming effect on ecosystem, we conducted a full year measurements of plant community, belowground biomass, leaf and root function traits under artificial warming conditions by using OTCs in alpine meadow and swamp meadow in the permafrost region of Fenghuoshan area on the Qinghai-Tibet Plateau. This paper provides a reliable mechanism for data support for further assessment of climate warming on the alpine meadow and alpine swamp and contribute to improving the dynamic balance of carbon and nitrogen cycle in the Tibetan Plateau.1 Over four years of warming, the air temperature in the OTCs plots was 2.52 ℃ and 2.95 ℃ higher than the control plots in the alpine meadow, and the swamp, respectively, during the growing season. The soil moisture at 5 cm decreased by 3.45% in the OTCs in alpine meadow, and soil moisture at 20 and 40 cm increased by 4.1% and 7.31%, respectively. The soil moisture content at 5, 20, 40cm increased by 5.26%, 3.54% and 0.93% in the alpine swamp during the growing season.2 There was no effect of the warming treatment on species richness, Shannon-wiener index, Simpson diversity index in the meadow or the swamp. Vegetation height increased over time in the meadow, and significantly more in the OTCs than in the controls. Contrastingly, the vegetation height in the alpine swamp decreased steadily over the study period both in the control and in OTCs but was higher in the OTCs. There was no effect of warming on the cover of graminoids, whereas warming increased the cover of forbs in the alpine meadow. There was no effect of warming on the cover of graminoids or forbs in the swamp.3 Warming increased the specific leaf area (SLA) of Elymus nutans in the alpine meadow and Carex scabrirostrisin the alpine swamp. Warming also increased the leaf dry matter content (LDMC) of Carex scabrirostris and Elymus nutans in the meadow, and of Carex scabrirostris in the alpine swamp. Warming had a significant effect on δ13C in all species in both communities, but the direction of the effect varied between species. Warming increased the δ13C value of Kobresia tibetica, but decreased the δ13C of the other four species in the meadow and the swamp. Warming increased the δ15N value of Kobresia pygmaea, but decreased it for Elymus nutans in the alpine meadow, and had no effects on any of the species in the swamp. Warming had no effect on leaf carbon concentration in any of the species in the alpine meadow, but affected both species in the swamp, with an increase of leaf carbon in Kobresia tibetica, and a decrease in Carex scabrirostris. Warming decreased leaf nitrogen concentration of all the species in the alpine meadow, but had no effect on any of the species in the swamp. Warming decreased the phosphorus content of Kobresia pygmaea, and had no effects on the other species in the alpine meadow and alpine swamp. Warming increased leaf C:N ratio of all the species in the alpine meadow, but had no effect on any of the species in the alpine swamp. Warming only increased the leaf C:P ratio of Kobresia pygmaea.4 Warming significantly increased the belowground biomass of 0-20cm in alpine meadow but no difference in swamp meadow, and had no effects on the belowground biomass of 0-10 and 10-20cm in the alpine meadow and alpine swamp. The results indicating that the sensitivity of belowground biomass to warming was higher in alpine meadow compared with swamp meadow. Warming significantly increased the root tissue density of 0-10 cm in alpine meadow and increased the root tissue density, total root length and total surface area of 10-20 cm. warming significantly increased the specific root length of 10~20cm in swamp meadow, and had no effect on other indexes. Warming significantly decreased the root C content of 0-10 cm and 10-20 cm soil layers in alpine meadow, and the root C content in 0-10 cm and 10-20 cm soil layers of swamp meadow was significantly increased. Warming had no significant effect on N content of 0-10 and 10-20cm in alpine meadow and alpine swamp
Pages60
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24579
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
彭阿辉. 模拟增温对青藏高原多年冻土区高寒草甸的影响[D]. 北京. 中国科学院大学,2017.
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