Knowledge Resource Center for Ecological Environment in Arid Area
| 克隆整合与植物对沙地生境的适应-毛乌素沙地的案例 | |
| 其他题名 | Clonal Integration and Plants’ Adaptation in Sandland－Case Studies in the Mu Us Sandland |
| 刘凤红 | |
| 出版年 | 2007 |
| 学位类型 | 博士 |
| 导师 | 董鸣 |
| 学位授予单位 | 中国科学院植物研究所 |
| 中文摘要 | 我国是受荒漠化影响最为严重的国家之一。半干旱区和干燥的亚湿润区分布着大面积沙地，这些沙地是我国荒漠化土地的集中分布区和的主要的潜在发生区，也是重点治理区。在这些地区进行生态建设和生态恢复的首要任务是植被的恢复与重建。用于植被恢复和重建的植物种，必需能够适应沙地特殊的生态环境。\n克隆植物是一个独特的植物类群，它广泛的分布于各种生态系统中。在长期的进化过程中，克隆植物形成了有效利用异质性资源以及克服（忍耐或逃避）局部不利环境条件的生态适应对策―克隆整合。位于鄂尔多斯高原的毛乌素沙地是我国的四大沙地之一，其生态环境的特点具备我国沙地生境的共性－干旱、土壤贫瘠、频繁的风沙活动以及异质性。在毛乌素沙地中，克隆植物广泛分布。本文以毛乌素沙地为案例研究的背景，以该区几种重要的克隆植物为研究对象，以该区主要的生态环境特点为处理因素，从不同层面来观察克隆整合对这些植物适应沙地环境的作用。\n高度异质性的水分分布格局是该区的关键生态因子之一。水分传输可以帮助克隆植物利用不同斑块内的水分资源。在一个野外实验中，采用酸性品红染色喂饲的方法，研究了根茎型草本克隆植物沙鞭和根茎型克隆半灌木羊柴的克隆内水分传播格局。沙鞭克隆内的水分传输速度和强度都高于羊柴。这可能是沙鞭能够占据大面积生境的原因之一。此外，克隆植物分株间资源的传递是通过贯通的维管束进行的。水分可以在观察的沙鞭克隆片断内畅通无阻的传输，但在羊柴克隆内的传输受到限制。这可能与二者维管束结构的不同有关。\n沙埋是该区植物经常遭遇的生态事件。本文研究了克隆整合在羊柴遭受空间异质性沙埋过程中的作用。结果表明，轻微程度的沙埋可以促进羊柴的生长和生物量积累；高强度的沙埋会削弱羊柴的生长和生物量积累，甚至会致死。克隆整合可以帮助羊柴抵抗空间异质性沙埋，尤其当沙埋的强度增加时，这种作用表现的更明显。实际上，沙埋的发生是逐渐进行的，即同时具有时间异质性。本文通过野外实验观察了沙鞭在时空异质性沙埋条件下的响应格局以及克隆整合的作用。研究表明，长时间间隔的沙埋促进沙鞭的生物量积累，克隆整合可以帮助沙鞭抵抗频繁发生的沙埋事件。此外，通过Meta-analysis方法综合了分布在沙地中的根茎型克隆植物对沙埋的响应格局的案例研究。结果表明，轻微的沙埋能够促进根茎型克隆植物的生物量积累，高强度的沙埋对这些植物是一种生态胁迫，克隆整合可以帮助这些植物抵抗这种生态胁迫。这强烈的支持了这样一种观点，即克隆整合是根茎型克隆植物在长期的适应进化过程中形成的抵抗高强度沙埋的生态策略。\n该区也生长着很多密集型克隆植物。养分的空间异质性在各种尺度上存在，密集型克隆植物也可能经历小尺度的养分异质性。以糙隐子草为研究对象，观察其在同质和异质养分条件下的生物量、生物量配置格局以及有性繁殖和克隆生长的权衡。结果表明：在异质性的养分条件下，相连的克隆片断的总体生物量、地上无性结构生物量、根生物量以及分株大小都显著高于切断的克隆片断；同样，异质性斑块中的相连的克隆片断的表现高于同质性斑块。这暗示着克隆整合能够帮助密集型克隆植物糙隐子草更好的利用小尺度的养分异质性。\n此外，通过野外调查的方式观察该区两种重要的克隆半灌木，游击型的羊柴和密集型的油蒿在小尺度不同植被盖度斑块下的生物量配置格局。结果表明：羊柴的地上各部分生物量对植被盖度变化的响应不如油蒿敏感。这可能是因为羊柴的游击型克隆构型决定其可以跨越小尺度斑块实现克隆生理整合，从而利用不同小生境斑块的资源所致。油蒿只能利用小生境斑块内的资源，当小生境斑块的条件改变，其生物量以及配置方式也随之发生相应的变化。在繁殖方式上，羊柴的有性繁殖结构以及有性繁殖投资显著小于油蒿。在资源有限的条件下，对一种繁殖方式的投资常常会削弱另一种繁殖方式。羊柴主要依靠克隆生长，这符合并支持配置理论的观点。植物的空间格局与植物自身的生活史性状密切相关。羊柴和油蒿不同的生活史特性必然会在各自的种群空间格局中体现出来。本文还采用地统计学的方法，观察二者的种群空间格局。种群水平上，小尺度的空间自相关控制着羊柴种群的空间格局；油蒿种群的空间格局受更大尺度的过程控制，并在自身为建群种的群落随机分布。对于油蒿种群而言，发生在小于抽样尺度（<1m）的随机变异高于相应的羊柴种群。这两种克隆半灌木的种群空间格局的差异可能与二者克隆构型和克隆性的不同有关。\n本文的研究对象不仅涉及根茎型克隆草本植物，还包括了克隆半灌木，不仅涉及游击型克隆植物，而且涵盖了密集型克隆植物。因此，本文的研究不仅有助于在理论上理解克隆植物对异质性生境的适应策略，在实践上也能为该区的生态恢复提供一定的理论依据。 |
| 英文摘要 | China suffers from one of the world’s most serious desertification problems. Desertification has made grisliness impacts on China’s booming economy and harmonious development. Sandlands with large areas are distributed in the arid, semi-arid and dry sub-humid zones, which have been desertificated and have much potential to enlarge. Ecological recovery is greatly important and strategically significant. The sand-binding vegetification in these areas may be the most appropriate method to solve this problem. There are many clonal plants in the Mu Us sandland, the second largest one in China. During their long-term evolutionary processes, they may take the adaptive strategy-clonal integration to cope with the heterogeneous environments. The studies on them not only make further understanding of the adaptive mechanisms of clonal plants, but also can provide basic information for practice. \nDrought and heterogeneous water distribution are the key ecological events that plants have to face. Water translocation within a clone can help clonal plants to utilize water in different microsites. In a field experiment with two rhizomatous species Psammochloa villosa and Hedysarum laeve, we investigated water translocation patterns using water-soluble acid fuchsin feeding method. The water translocation patterns in terms of intensity and extensity differed between the two plant species. The results suggest that P. villosa is an extensive and intensive integrator, whereas H. laeve is a restrictive and less intensive integrator, implying why P. villoca can span more patches and occupy larger area in the habitat. The vascular architectures may partly explain their differences.\nRecurrent sand burial is one of the environmental stresses for the plants in the sandland. In fact, sand burial has both spatial and temporal heterogeneities. We conducted two field experiments to study the responsive patterns of the rhizomateous semi-shrub, H. laeve subjected to spatial heterogeneous sand burial, and the rhizomateous grass P. villosa when sand burial occurs in temporal heterogeneous way, respectively. The modified effects of clonal integration were emphasized. The results showed that slight sand burial with long-term interval could facilitate biomass accumulation; heavy and frequent sand burial reduced biomass while clonal integration could reverse the negative effects to some extent. In addition, using meta-analysis we synthesized the case studies with the rhizomatous clonal plants in the sandlands of China. The results are consistent with those of case studies, indicating that rhizomateous clonal plants in these areas adapt to sand burial by clonal integration, which may be formed during the long-term evolutionary process.\nThere are many phalanx clonal plants in this area and effects of clonal integration on their adaptive capacities are studied by field surveys and experiments. Spatial heterogeneity in nutrient availability exists even at scales of centimeters. We investigated whether clonal integration may also benefit bunchgrass Cleistogenes quarrosa in heterogeneous nutrient supply. In patchy conditions, its performances of the connected clonal fragments were markedly higher than those of disconnected ones. Also connected clonal fragments produced significantly more biomass and more and larger tillers in patchy conditions than in homogeneous ones that were provided the same amount of nutrients as in the patchy treatments. We conclude that clonal integration enables phalanx clonal species to use small-scale soil heterogeneity better, so that they may grow better in conditions with heterogeneous nutrient supply.\nBesides, we compared the population spatial patterns and biomass allocation between the important clonal semi-shrubs, guerrilla H. laeve and phalanx Artemisia ordosica. H. laeve was less sensitive to the variation of vegetation coverage than A. ordosica. Whole aboveground biomass, reproductive biomass, stem biomass and leaf biomass of H. laeve did not vary as vegetation coverage while A. ordosica did. In addition, reproductive biomass and allocation of H. laeve were lower than those of A. ordosica. These results implicated that the guerrilla H. laeve could utilize resources in different microhabitats using clonal physiological integration. Compared to H. laeve, A. ordosica relied more on sexual reproduction to produce offspring. Auto-correlation on small scale controlled the spatial patterns of H. laeve populations and the auto-correlation scale was consistent with length to which its rhizomes horizontally spread. A. ordosica population was randomly distributed in itself dominated communities. Perhaps it was because A. ordosica population maintains and recruits mainly through seeds. Small-scale (<1m) stochastic variation was larger in A. ordosica population than in H. laeve. It is likely that spatial patterns of the two clonal plant populations were closely related to their clonalities and clonal architectures. |
| 中文关键词 | 克隆构型 ; 克隆整合 ; 克隆植物 ; 沙地 ; 沙埋 ; 水分传播 ; 生殖格局 ; 投资权衡 |
| 英文关键词 | clonal architecture clonal integration clonal plant reproductive patterns sandland sand burial sandy |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286525 |
| 推荐引用方式 GB/T 7714 | 刘凤红. 克隆整合与植物对沙地生境的适应-毛乌素沙地的案例[D]. 中国科学院植物研究所,2007. |
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