Knowledge Resource Center for Ecological Environment in Arid Area
| 呼伦贝尔草甸草原小哺乳动物群落共存机制研究 | |
| 其他题名 | Exploring the mechanisms of small mammals coexistence in Hulunber Meadow Steppe |
| 曹婵 | |
| 出版年 | 2017 |
| 学位类型 | 博士 |
| 导师 | 杜卫国 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 共存理论是生物多样性和群落生态学研究中的一个核心议题，中性理论和生态位理论是最重要的两个共存理论。竞争导致的同域物种之间的分化促进了物种的共存。关于小哺乳动物群落共存机制的课题，生态学家们在荒漠生境中开展了大量的研究工作，发展了诸多共存机制。而生活在草原，特别是东亚草甸草原，的小哺乳动物群落的共存机制较少受到关注。我用5年的时间从生态位理论角度入手对内蒙古呼伦贝尔草甸草原中的小哺乳动物群落的共存机制进行了研究，得到了关于共存的一些线索。根据经典的生态位理论，栖息地分化是促进物种共存最普遍的方式。我研究了小哺乳动物群落如何响应不同放牧强度导致的生境差异，发现在轻度放牧（0.23 Au/ha）条件下，小哺乳动物群落生物多样性最高。随着放牧强度的增加，小哺乳动物群落的结构逐渐单一化，达乌尔黄鼠打破多物种分割生境的格局逐渐成为群落内的优势种，CCA分析表明这种变化与植物群落盖度和生物量的减少以及土壤硬度的增加具有一定的相关性。不同物种对放牧的响应也不同，达乌尔黄鼠对放牧造成的开阔生境更加适应。此外不同季节群落结构的组成也存在差异。作为第二重要的生态位维度，营养生态位的分离也可能促进了物种的共存。我用室内饲喂和胃内容物显微组织分析两种方法测量并比较了群落中常见的3种小哺乳动物狭颅田鼠（Microtus gregalis）、达乌尔黄鼠（Spermophilus dauricus）和达乌尔鼠兔（Ochotona daurica）的营养生态位宽度和重叠度，以及食物偏好度。结果表明，三种鼠之间存在明显的营养生态位分化。所有物种的营养生态位宽度在野外条件下缩减至实验条件下的一半，物种之间的营养生态位重叠度也减少了。野外和实验条件下物种的采食偏好格局迥异。达乌尔黄鼠的生态位宽度始终是最窄的，而狭颅田鼠在野外的生态位宽度变成最宽；达乌尔黄鼠和达乌尔鼠兔的营养生态位重叠度最高，在实验室高达0.80；三种鼠的采食偏好的种类有显著差别，但偏好的植物物种数接近。之前的研究表明狭颅田鼠和达乌尔黄鼠在时间生态位上有所区分，特别是在黄鼠入蛰后，田鼠的日活动高峰迁移到黄鼠原来活动高峰的时段。我们在半自然围栏内进行经典的物种添加实验，检测黄鼠的存在是否与田鼠节律的迁移有关，并对环境温度与田鼠活动格局作了线性回归。结果证明田鼠的日活动格局更多地是对随季节变迁的外温变化的响应，与黄鼠入蛰与否的相关性不大。此外，捕捉数据也间接显示了田鼠对黄鼠存在一定的空间回避。尺度效应提示我们物种的分化可能发生在更小的尺度上，那么狭颅田鼠和达乌尔黄鼠是如何在更精细的尺度上互作的？借鉴荒漠采食行为和放弃密度研究的成功案例，我设计了一套适用于草原的人工食盘装置，并结合视频监控拍摄从技术上实现了测量更精细时空尺度的可能性。双食筐实验结果表明：田鼠和黄鼠不会同时出现在同一个视频拍摄范围内，也就是有半米间隔的双食筐及周边区域；两种鼠的日活动格局的单峰性如果下推到小时甚至分钟的采样单元上会解析出很多活动高峰，在这些尺度上它们存在明显的采食活动错峰。此外田鼠和黄鼠的采食策略也有显著差别：田鼠是带走采食者，而黄鼠是就地采食者。综上，我们从空间、营养、时间以及行为策略等角度研究了呼伦贝尔草原常见物种的共存机制，构建了一套较为完整的东亚草原小哺乳动物共存的框架。 |
| 英文摘要 | Coexistence theory belongs to the core issues of biodiversity and community ecology. Among numerous related theories, neutral theory and niche theory are the most important two. Resource partitioning among sympatric species stimulated by competition prompted their coexisting. As referred to small mammals, there exist plenty of excellent researches on mechanisms of their coexistence in deserts. However, coexistence mechanisms for rodents living in grassland ecosystem, especially for East Asian meadow steppe, are poorly understood. In the light of niche theory, I studied on this topic in Hulunber meadows for five years and gained some clues for the coexistence.In the view of niche theory, habitat segregation is the most popular way to promote species coexistence. I studied how small mammal community response to the different habitat under four levels of grazing intensities in Hulunber meadow steppe. We found species richness and diversity of small mammals in ungrazed and lightly grazed (0.23 animal unit/ha) area were much higher than in intermediately and heavily grazed area. Dramatic changes in species composition in native small mammal communities when grazing intensity reached intermediate levels (0.46 animal unit/ha), as Spermophilus dauricus gradually became the single dominant species. According to CCA analysis, these variations were related to the changes of environmental variables such as declined vegetation coverage and biomass and increased soil hardness. Rodent species had distinctive response to different grazing levels, such as S. dauricus prefers open habitat created by intensively grazing. In addition, different species were active in different months. Consider the second important dimension - trophic niche, I measured and compared trophic niche breadths, overlaps and food preferences among Microtus gregalis, S. dauricus and Ochotona daurica by feeding experiment and stomach microhistological analysis. There existed notable shrunk dietary breadth, declined overlap and significant interspecific variation in food preference of the triads in the field comparing to the laboratory. S. dauricus occupied the narrowest niche breadths in both conditions, while M. gregalis became the widest niche breadth holders in the wild. The overlap between S. dauricus and O. daurica were highest in both conditions with the value reaching to 0.80 in the laboratory. The triad had distinct food preference patterns while the numbers of favorite food items were not distinguished. Pilot study suggested that M. gregalis shifted its diel activity pattern once S. dauricus hibernated. We conducted a classic additive experiment in rodent-proof enclosures to test S. dauricus’ effect on diel activity pattern of M. gregalis. We measured the ambient temperature meanwhile and conducted a linear regression between temperature and trapping frequencies. We found that the presence of S. dauricus did not significantly affect the diel activity patterns of M. gregalis. Timing of activity of M. gregalis, however, was always significantly correlated with ambient temperature (P < 0.001). As winter approached, ambient temperature appeared to be a major factor in shaping activity patterns of M. gregalis. Besides M. gregalis spatially avoided the inference of S. dauricus according to trapping records.Scaling effects reminds us the niche partitioning of M. gregalis and S. dauricus may happen on a finer scale. Meanwhile I wonder how the couples interact on the finer scale. Refer to the successful case study on foraging behavior and giving-up density of rodents in deserts, I designed a food tray set which was adaptive to the steppe, and combined it with surveillance video records to measure the rodents’ interaction and foraging behavior on a finer scale. Double food basket experiment told us M. gregalis and S. dauricus could never occurred in the same vision field shot by video simultaneously. When we settled the diel activity pattern down to per hour even per minute, the unimodal distribution would break into various activity peaks. M. gregalis and S. dauricus separate their activity patterns on this scale, and their also had disparate foraging strategies with M. gregalis was a “carry-and-go” forager while S. dauricus was an “eat-at-tray” forager.To conclude, we studied on the coexistence of rodents living in Hulunber from spatial, trophic, temporal and behavioral strategies, and painted a complete picture for small mammal coexisting in East Asian steppe. |
| 中文关键词 | 呼伦贝尔 ; 生态位理论 ; 干扰竞争 ; 小哺乳动物群落 ; 尺度效应 |
| 英文关键词 | Hulunber Niche theory Interfere competition Small mammal community Scaling effects |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院动物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287832 |
| 推荐引用方式 GB/T 7714 | 曹婵. 呼伦贝尔草甸草原小哺乳动物群落共存机制研究[D]. 中国科学院大学,2017. |
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