Knowledge Resource Center for Ecological Environment in Arid Area
| 科尔沁沙地植被-土壤碳、氮、磷化学计量特征研究 | |
| 其他题名 | Stoichiometry carbon, nitrogen and phosphorus in vegetation and soil in Horqin sandy land |
| 宁志英 | |
| 出版年 | 2019 |
| 学位类型 | 硕士 |
| 导师 | 李玉霖 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 生态化学计量学作为研究生物系统能量平衡及元素平衡对生态过程和生态作用交互影响的一门学科，主要关注碳（C）、氮（N）、磷（P）三种元素间的数量关系，对于我们更好地认识生态系统各组分养分比例的调控机制，及养分比例在生态系统过程及功能中的作用具有重要意义。陆地生态系统C、N、P化学计量学是近年来研究的热点问题，目前已取得很多重要研究成果，但由于相关的研究起步较晚，当前仍有很多方面存在不足。例如对植物根系化学计量特征、生态化学计量关系在各尺度上的统一，以及植物-土壤化学计量关系及与生态系统结构与功能间的关系等问题的关注仍较缺乏。因此，本文以科尔沁沙地为研究对象，通过野外调查试验，开展植被-土壤C、N、P生态化学计量学的研究，分析科尔沁沙地植物个体及群落水平上，以及土壤的C、N、P化学计量特征；揭示科尔沁沙地主要植物叶片与细根C、N、P化学计量特征的关联性，以及优势固沙灌木的化学计量内稳性特征；阐明沙质草地植物-土壤C、N、P化学计量关系与植被生产力及群落结构间的内在联系，以期为进一步认识沙质草地植物的养分利用策略、沙质草地生态系统功能及其稳定维持机制，以及沙漠化发展的生态学机理提供科学依据。主要研究结论如下：（1）科尔沁沙地60种主要植物叶片平均C含量、N含量、P含量和C:N:P分别为424.20 mg·g–1、25.60 mg·g–1、2.10 mg·g–1和202:12:1。细根平均C含量、N含量、P含量和C:N:P分别为434.03 mg·g–1、13.54 mg·g–1、1.13 mg·g–1和384:12:1。细根的N、P含量近似等于叶片平均N、P的1/2，而叶片与细根的N:P无显著差异；不同生活型间叶片和细根的C、N、P含量及其化学计量比存在显著差异，杂类草植物具有较高的叶片N、P含量，禾草类植物具有较高的叶片C:N、C:P，一年生杂类草和禾草类植物叶片的N:P较低，豆科植物具有较高的C、N含量和较低的C:N。（2）科尔沁沙地沙化草地群落具有较低的N、P含量，群落地上生物量和地下生物量C:N:P的平均质量比分别为294:9:1和479:9:1。不同程度沙化草地间群落地上和地下生物量的C、N、P化学计量特征存在显著差异，草地沙漠化过程中，群落N含量、P含量显著降低，而C:N、C:P显著升高。（3）科尔沁沙地沙化草地表层土壤具有较低的有机C、N、P含量及C:N、N:P和C:P，且草地沙化过程中，有机C、N、P含量及C:N、N:P和C:P均显著降低；沙化草地表层土壤有机C、N、P元素间具有一定的耦合关系，且这种耦合关系并不随沙漠化的发展而改变。（4）与差不嘎蒿相比，优势固沙灌木小叶锦鸡儿具有较高的叶片N含量及N:P，而P含量仅为差不嘎蒿的1/2；两种优势灌木灌丛下土壤因“沃岛效应”较该地区土壤具有较高的全N、全P含量及速效N、速效P含量，小叶锦鸡儿灌丛下土壤全N、全P含量及速效N、速效P含量均显著高于差不嘎蒿；差不嘎蒿叶片氮磷化学计量内稳性指数表现为HP>HN:P>HN，说明差不嘎蒿更易受土壤N的限制；小叶锦鸡儿叶片氮磷化学计量内稳性指数表现为HN:P>HN>HP，意味着小叶锦鸡儿更易受土壤P的限制。（5）在植物个体水平上，叶片和细根的N、P含量间显著正相关，细根C含量与N含量之间以及C含量与P含量之间显著负相关；叶片和细根间的C、N、P及化学计量比存在显著的正相关关系。群落水平上，沙化草地群落地上生物量、地下生物量的N、P和C、P含量显著正相关，地上生物量C、P含量呈显著负相关；并且群落地上生物量和地下生物量之间的N含量、P含量、C:N、N:P及C:P亦均显著正相关;不同沙漠化程度草地群落地上生物量和地下生物量间的C、N、P化学计量相关性存在一定差异。表明无论是个体还是群落水平，C、N、P元素间具有一定的耦合关系，以及光合产物与养分在地上、地下部分之间分配比例的一致性配具有平行的比例关系。（6）沙化草地植物群落C、N、P化学计量特征与土壤养分及群落结构有一定的相关性。沙化草地群落N、P含量与土壤N含量、P含量及N:P间显著正相关，而群落C:N、C:P与土壤养分指标间显著负相关，表明植物群落对单一养分的吸收利用并不是独立的，其依赖于土壤中各元素的平衡状况；群落N、P与群落内豆科植物和杂类草植物所占比例显著正相关，而与禾本科植物显著负相关，群落C:N、C:P均与群落内禾本科植物所占比例显著正相关，而与豆科和杂类草植物显著负相关，表明群落C、N、P化学计量特征受群落结构的影响，禾本科植物有利于提高群落养分利用效率。 （7）草地沙化过程中，土壤养分的损失限制着草地生产力，而土壤N:P较N、P含量更能反映土壤养分对生产力的限制作用；沙化草地土壤N含量与物种丰富度间具有显著正相关关系，而土壤P与其无显著相关性，相对于土壤N、P含量，N:P能更好地反映养分平衡对物种丰富度的影响作用。 |
| 英文摘要 | As a discipline to study the interaction between energy balance and element balance of biological system on ecological process and ecological action, the main concern of stoichiometry is the quantitative relationship between carbon (C), nitrogen (N), phosphorus (p) and three elements, so as to better understand the regulation mechanism of nutrient ratios in various components of ecosystems, and the role of nutrient ratio in ecosystem processes and functions is of great significance. The stoichiometry of terrestrial ecosystem C, N and P has been a hot topic in recent years, and many important achievements have been made, but there are still many problems because of the late start of related research. For example, there is still a lack of attention to the stoichiometric characteristics of plant roots, the unification of the ecological stoichiometry relationship in different scale, and the relationship between plant-soil stoichiometric relationship and the relation between ecosystem structure and function. Therefore, this paper takes Horqin Sandy land as the research object, through field investigation, the study of ecological stoichiometry of vegetation-soil C, N and P was carried out to analyze the characteristics of the plant individual and community level in Horqin Sandy land, as well as the C, N and P stoichiometric characteristics of soil. Thereby, it reveals the correlation of stoichiometric characteristics of the main plant leaves and fine roots C, N, P, and the stoichiometric homoeostasis of the dominant sand-fixing shrubs, and illustrates the relationship between the stoichiometric relation of plant-soil C, N, P and the vegetation productivity and community structure in sandy grassland, in order to further understand the nutrient utilization strategies of sandy grassland plants, the ecosystem function of sandy grassland and its stable maintenance mechanism, as well as the ecological mechanism of desertification development, providing scientific basis. The main results are as follows:(1) The average C, N and P concentrations in leaves of 60 plant species in Horqin sandy land are 424.20 mg g–1, 25.60 mg g–1 and 2.10 mg g–1, respectively. In fine roots, the corresponding element concentrations are 434.03 mg g–1, 13.54 mg g–1, 1.13 mg g–1. N and P concentrations in leaf are approximately twice as high as averages in fine root. There are significant difference of C, N, P, C:N, C:P and N:P in leaf and root among five life forms. N and P in forb and C:N and C:P in grass are averagely higher than those in other life forms. N:P ratio in annual forb and grass, however, are lower than those in other life forms. C, N in legume are higher than those in non-legume, while C:N in legume is lower than in non-legume.(2) The sandy grassland community in Horqin Sandy Land has lower N and P content, and the average mass-based C:N:P of the aboveground and underground biomass is 294:9:1 and 479:9:1 respectively. There were significant differences in the stoichiometric characteristics of C, N and P between the aboveground and underground biomass of the grassland, and the N content and P content in the grassland desertification process decreased significantly, while the C:N and C:P increased significantly.(3) The concentrations of organic C, total N, total P, and their ratios in topsoil of desertified grasslands remained a relatively low level in contrast with the results nationwide or worldwide. It was not surprised that soil C, N, P significantly decreased during grassland desertification. Their ratios, however, also significantly decreased in the gradient of desertification. Topsoil C, N, P, and their ratios of desertified grassland were significantly coupled in the study sites. Furthermore, the coupling relationships did not change with the development of grassland desertification.(4) Compared with the sand-fixing shrub Artemisia halondendron, Caragana microphylla has higher leaf N content and lower leaf P content, thereby higher leaf N:P ratios. The soil under the canopy of the two dominant shrubs had higher total N, P contents and available N, P contents realive to the soil outside the canopy. Moerover, total N, P content and available N, P in soils under Caragana microphylla canopy were relatively higher than those under Artemisia halondendron canopy. As a results, the order of stoichiometric homoeostasis indexes in Artemisia halondendronwas HP>HN:P>HN, and HN:P>HN>HP in Caragana microphylla suggesting N restriction Artemisia halondendron but P restriction in Caragana microphylla .(5) At the individual level of the plant, N and P in leaf or fine root positively correlated, but C and N, C and P in fine root negatively correlated. There were significant positive correlations between the C, N, P and stoichiometric ratios between the leaves and the fine roots. In the community level, aboveground or underground biomass N and P contents was positively correlated, while aboveground biomass C and P contents was significantly negatively correlated. Furthermore, corresponding element content and their ratios between aboveground and underground biomass were also positively correlated except C contents. The correlations of C, N, P stoichiometry between aboveground and underground biomass of desrtified grassland communities were incongruous along the gradient of desertification. The results show that there is a certain coupling relationship between the elements C, N and P, both in individual and community level, and there is also a parallel proportional relationship between photosynthetic product and nutrient distribution ratio between aboveground and underground.(6) The stoichiometric characteristics of C, N and P in sandy grassland were correlated with soil nutrients and community structure. Desertified grassland community N, P content was positively correlated with soil total N, total P and N:P ratio, while community C:N and C:P were significantly negatively correlated with soil nutrient, which indicated that the absorption and utilization of plant community to single nutrients was not independent, and depended on the equilibrium state of each element in soil. Community N, P has a significant positive correlation with the compositional proportions of legumes and forbs in the community. Community-level C:N and C:P, however, were positively correlated with the compositional proportion of gramineae in the community, and negatively correlated with he compositional proportion of legume sand forbs, which indicated that the stoichiometric characteristics of community C, N and P were influenced by community structure, the grass plant is beneficial to improve the nutrient utilization efficiency of the community.(7) Community productivity was limited by the loss of soil nutrient in desertified grassland in the study. However, soil N:P stoichiometry could explain more variations of community productivity than soil N or P concentration. Similarly, correlations analysis showed that species richness are significantly correlated with soil N, but this case is not for P. Compared with N or P concentration, soil N:P stoichiometry can effectively reflect the influence of nutrient balance on species richness. |
| 中文关键词 | 生态化学计量学 ; 根系 ; 群落 ; 土壤 ; 群落结构 |
| 英文关键词 | ecological stoichiometry roots community soil productivity community structure |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288224 |
| 推荐引用方式 GB/T 7714 | 宁志英. 科尔沁沙地植被-土壤碳、氮、磷化学计量特征研究[D]. 中国科学院大学,2019. |
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