NWIPB OpenIR
高寒草甸植物和植物群落对增温和放牧的响应与适应研究
徐广平
学位类型博士
导师汪诗平
2010-06-01
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业生态学
关键词增温 放牧 物候 点格局 生物量 地上净初级生产力 功能型 多样性 高寒草甸
摘要以全球变暖为主要特征的全球气候变化已经并正在改变着陆地生态系统的结构和功能。政府间气候变化专门委员会(IPCC)第四次评估报告预测,到本世纪末,全球平均气温将升高 1.8~4.0℃。科学家普遍认为高纬度和高海拔生态系统
对温度升高的响应可能会更为敏感而迅速。本研究以高寒草甸主要植物和植物群
落为研究对象,在野外自然条件下进行生态系统控制性自由空气增温(Free-air
temperature enhancement)(FATE)与放牧试验,共4 种处理(不增温不放牧(NWNG)、不增温放牧(NWG)、增温不放牧(WNG)和增温放牧(WG))每种处理4 个重复、16 个小区进行完全区组随机设计,从而探讨高寒草甸植物和植物群落对增温和放牧的响应与适应机理和过程。结果表明:
1、环境条件变化。通过3 年(2006~2008)增温(白天+1.2℃,晚上+1.7
℃)与放牧耦合试验研究,增温显著地增加了白天和晚上植被冠层温度达1.18
和1.69℃,说明该增温装置完全能满足我们预先设置的增温幅度(白天和晚上分别增温1.2℃和1.7℃)。增温显著增加10cm 土壤温度1~1.4℃左右;放牧也显著增加了10cm 土壤温度1℃左右。2006 年和2007 年,增温对0-10、10-20cm 土壤湿度的影响不显著,但显著降低了20-30cm 土壤6 月中旬以前的湿度;但在干旱的2008 年,增温显著地降低了10cm 土壤湿度。
2、放牧处理牧草利用率。2006、2007 和2008 年,NWG 处理年牧草累积利
用率分别为32.4%、44.3%和60.8%,WG 处理年牧草累积利用率分别为31.7%、49.9%和56.4%。说明绵羊放牧水平是适度放牧,达到了我们预期试验设计的要求。
3、物候期变化。短期增温使植物种群水平和不同功能型植物物候返青始期、
现蕾期和结实末期均提前,而枯黄期均延迟;使群落水平植物物候开花始期、开
花末期、结实始期、结实末期和返青始期均提前,枯黄末期推后。因此,尽管不
同物种物候的敏感程度不同,但高寒草甸植物种群、功能型和群落水平物候对模
拟增温响应的方式基本一致,增温和放牧延长了植物的生长季2-3 周。放牧主要
提前了植物和植物群落的返青始期,对枯黄期的影响较小;相反,增温主要延迟
了枯黄期,而对返青期影响较小。
4、空间点格局的变化。短期增温促使不同植物个体和植物功能型主要以聚集分布为主或向更聚集方式的空间分布,使小尺度的种间隔离来降低种间的竞争
强度,从而改变了不同物种对资源和空间的竞争能力,有利于植物种群的更新。
而放牧则减缓或抵消了这种趋势,使种群的空间分布由聚集分布趋向为随机分
布。同一植物种群和同一植物功能型空间分布格局在不同尺度上具有尺度依赖
性,在不同尺度下会表现出不同的空间分布特征。
5、空间异质性和种间关系变化。2006 年和2008 年不同植物功能型物候都
已发生变化,而2006 年植物分布格局没有发生显著变化,到2008 年植物分布格局发生了显著变化,这说明植物点格局的变化滞后于物候的变化。增温增加了植物空间异质性,而放牧则削弱了这种趋势。植物种间相互作用(空间关联)与增温和放牧引起的植物空间异质性共同决定了高寒草甸植物的小尺度空间分布格
局,植物空间格局的变化可能驱动了退化高寒草甸植物群落的恢复演替。
6、物种丰富度和多样性变化。在3 年增温和放牧试验的较短时间内,物种
丰富度并没有发生明显变化,没有改变植物的Shannon-wiener 多样性指数,只是相对提高了物种Pielou 均匀度指数。适度放牧可以降低群落优势种排斥其他物种的能力,并没有降低植物物种多样性。而植物间负相互作用趋向减少,正相互作用趋于增加,从而增加了两个相互作用物种共存的可能性。
7、初级生产力变化。增温显著增加了牧草的生长速率,无论是否放牧增温
都显著增加了地上净初级生产力(ANPP),但放牧减弱了这种变化趋势。增温增加了禾草在群落中的盖度和高度,但放牧减缓了这种变化趋势。夏季适度放牧提高了高寒草甸植物的再生速率,甚至在干旱年份能促使放牧植物超补偿生长,但若同时增温和放牧,在干旱年份放牧则导致低补偿性生长。总体上,只有增温不放牧处理显著增加了0-40cm植物地下生物量,主要是增加了0-10cm地下生物量,其他3 种处理间差异不显著。ANPP 和土壤温度(0-10cm)呈显著正相关、和土壤湿度(0-10cm)呈显著负相关,这说明在高寒地区植物生长主要由于低温的限制,而不是土壤湿度的限制;同时发现增温导致植物功能型组成的变化可能是导致ANPP 变化的主要原因。
其他摘要

Global climate change characterized by global warming has been changing the structure and function of terrestrial ecosystem. According to International Panel on Climate Change 2007, global air temperatures are predicted to increase 1.8~4.0℃ over this century. It has been generally predicted that the responses of terrestrial
ecosystems in arctic and high mountain regions to global warming could be more sensitive and faster. Alpine meadow ecosystems are considered to be the key zones in response to raising temperature. In this study,the responses and adaptations of plant and plant community to warming and grazing on the alpine meadow of the
Qinghai-Tibetan plateau were studied using the controlled FATE(Free-air temperature enhancement)and grazing experiment from 2006 to 2008. The experiment included 4 treatments (no-warmring with no-grazing (NWNG), no-warming with grazing (NWG), warming with no-grazing (WNG) and warming with grazing (WG)) with 4 replicates each treatment. The results are as follows:
1. Environmental responses. Warming(+1.2℃ during daytime and +1.7℃ at nighttime) increased 10 cm soil temperature about 1.0℃~1.4℃, and grazing increased 10 cm soil temperature about 1.0℃. However, there was no significant impact on soil moisture for warming and grazing in 2006 and 2007, but warming decreased 10cm soil moisture during drought-year of 2008.
2. Forage untilization rates for grazing treatments. The cumulative forage utilization rates of annual ANPP during the growing seasons were 32.4%, 44.3%, and 60.8% for NWG, and 31.7%, 49.9%, and 56.4% for WG in 2006, 2007, and 2008, which belonged to the range of light to moderate grazing in the region, respectively.
3. Phenoloical responses. Experimental warming and grazing advanced starting green time, starting bud, starting flowering time, ending flowering time and ending seed time of plant, for different plant species, different functional types and plant community. However, warming delayed the color phonological periods. Therefore,
warming and grazing prolonged the plant growth period up to 2-3 weeks in the region even though different plants had different responses. Interactive effects between warming and grazing on the phenology of plant species and plant community were observed.
4. Spatial distribution. Different plant species and different function types mainly showed clumped distribution with warming, but it was weakened even altered by grazing. Small scale inter-specific isolation may decrease the intensity of inter-specific competition and change the abilities of different species to compete recourses and interspace, which was conducive to restoration succession of community. Spatial patterns were depended on different spatial scales.
5. Spatial heterogeneity and relationships between plant species. The change of spatial point pattern followed the change of phenology. Warming increased the spatial heterogeneity of different plant function types, but grazing decreased their spatial heterogeneity. Small scale spatial heterogeneity and inter-specific interactions may be altered through climate warming and grazing and seem to be the main controlling factors of the spatial pattern of different function types in the alpine meadow. Finally it may drive restoration succession of community composition and structure for the degraded alpine meadow.
6. Plant species richness and biodiversity. Warming and grazing did not significantly influence plant species richness and plant Shannon-wiener diversity index, but experimental warming improved plant Pielou evenness. Positive interaction between different function types may promote species coexistence.

7. Primary production.Warming significantly increased forage growth rates and aboveground net primary production (ANPP), in contrast to grazing. Warming increased the proportion and height of grasses in the community, but grazing modified the changeable trends. The shifts of composition of grasses, forbs, and sedges may determine the response of ANPP to warming because most biomass was supplied by grass function type. Over-compensation of ANPP was found in grazing during the year 2008, whereas grazing with warming resulted in below-compensation. Warming significantly increased belowground biomass in 0-40cm, particularly in 0-10cm. The positive and negative relationships were found between ANPP and soil temperature and soil moisture in the region, respectively, indicating that low soil temperature rather than soil moisture limits the plant growth in the alpine meadow.

学科领域生物科学
语种中文
文献类型学位论文
条目标识符http://210.75.249.4/handle/363003/3394
专题中国科学院西北高原生物研究所
推荐引用方式
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徐广平. 高寒草甸植物和植物群落对增温和放牧的响应与适应研究[D]. 北京. 中国科学院研究生院,2010.
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