巩乃斯河流域典型草地生态学特征及土壤营养元素的空间异质性研究
文献类型：学位论文
| 作者 | 马杰 |
| 学位类别 | 博士 |
| 答辩日期 | 2015 |
| 授予单位 | 中国科学院大学 |
| 授予地点 | 北京 |
| 导师 | 李兰海 |
| 关键词 | 草地 生物量 养分 化学计量比 海拔梯度 |
| 学位专业 | 理学博士 |
| 中文摘要 | 伊犁是新疆及中国重点草原牧区区内，主要受西风环流的影响。研究伊犁河上游巩乃斯河流域典型草地生态学特征及土壤养分元素的空间异质性对于全面了解和预测我国半干旱地区草地生态系统对气候变化的敏感性具有重要的意义。受天山山体的海拔变化等因素影响，研究区内草地生态系统结构和格局空间异质性明显。本论文通过分析草地土壤各养分元素含量随高程变化的空间分布特征，揭示了研究区草地土壤养分的空间异质性、格局演化机制以及不同形态养分空间格局对高程变化的响应，分析了该区域不同草地类型的土壤有机碳分级，阐述了不同类型草地群落土壤不同形态有机碳（活性有机碳、慢性有机碳、惰性有机碳）的垂直分布格局。同时，对不同草地类型植物群落养分含量及其化学计量学比值的变化及空间分布特征进行了定量的探讨。从土壤养分和草地植物养分等不同角度揭示和阐明草地生态及生物地球化学特征。研究结果不仅有助于揭示新疆草地生态系统的演变规律及其生命物质循环特征，同时，也可为受损生态系统的植被恢复提供理论依据，为进一步保护草原生态系统提供数据支持。通过对研究区内野外样地考察以及对土壤和植物养分元素采样测定及统计分析，本研究得到如下主要结论： 1、草地各采样点表层土壤pH、碱解氮（AN）、速效磷（AP）、有效钾（AK）和有机质（OM）含量均随土壤深度增加逐渐降低，其它土壤养分元素含量随土壤深度变化波动未呈现明显规律。草地表层土壤的养分含量高，该研究区更适合浅根植物生长，可以人工播撒一些浅根草种，有助于草地生态系统的恢复。空间格局上，沿巩乃斯河流域土壤AN、AP、AK、OM和铁（Fe）含量由西向东逐渐增加。随海拔升高，土壤全钾（TK）含量减少；除此之外，全氮（TN）、全磷（TP）、硒（Se）含量呈先增加后减少的趋势，这表明中海拔土壤AN和AP高，可以看出中山带的土壤可以提供给植物可吸收利用的速效养分。TN、TP含量高表明土壤可以持久的提供养分，可以看出该海拔范围内土壤养分条件利于草地植物生长。 2、不同草地类型活性有机碳、慢性有机碳（或缓性有机碳）、惰性有机碳含量随土壤深度的增加而降低，这也与土壤有机质的变化规律一致。活性有机碳含量范围为0.070~1.553 g.kg-1，平均值为0.557 g.kg-1，其中表层土壤活性有机碳含量，山地草甸 >高寒草甸 >山地草甸草原 >半荒漠草原、荒漠草原。由此得出，山地草甸草原土壤含有更多容易被植物吸收利用的活性有机碳，该类草地利于植物生长。同时，该类草地惰性有机碳含量大于活性有机碳和慢性有机碳含量，土壤有机碳稳定性较好，利于土壤有机碳长期固定储存。 3、不同草地类型群落尺度下R/S的变化范围在0.3~8.6，平均值为2.9。可以根据R/S估算该研究区域草地根生物量及碳的分配比例与固定量。随海拔升高，Shannon-Wiener等植物生物多样性各指数和R/S呈先增加后减少的趋势。不同多样性指标反映了空间格局的一致性，可以看出中海拔地区各指标均最大，生物多样性丰富。可以考虑将低海拔地区的牲畜数量转移到中山带地区，减轻放牧压力，有利于退化草地的恢复。 4、不同草地类型地上部全碳（C）含量略高于地下部，分别为346.1 g.kg-1和341.8 g.kg-1。地上部中氮（N）、磷（P）含量平均值分别为13.6 g.kg-1和1.7 g.kg-1。根的N、P含量平均值分别为9.5 g.kg-1和1.4 g.kg-1。研究区地上部中N含量低于全国水平，P含量与全国水平一致，今后可加强对氮素的研究。地上部和根的化学计量学比值N/P平均值分别为7.5和7.1，表明氮元素是该区域植物生长的养分主要限制因子之一。 5、草地植物不同部位养分元素间存在显著相关性。地上部分全碳含量与地上部全氮、全钾含量极显著相关（p<0.01）。地上全氮和C/N比值呈负的相关性（p<0.05），与其它养分指标均呈极显著正相关（p<0.01）。地上磷含量与地上钾含量、地下部磷含量呈极显著相关（p<0.01），与地上C/N比值、根N/P比值呈负的极显著相关（p<0.01）。根据这些相关关系可以建立方程，定量化元素之间的关系，从而通过一种元素的变化来推测其它元素含量分布特征的变化。 |
| 英文摘要 | Ili is a vital grassland pasturing area in Xinjiang, China. It is of great importance to investigate the ecological characteristics as well as the biomass of typical grasslands in the Kunes River Basin, the upper stream of Ili River. As affected by the uplift of Tianshan Mountains and the westerly circulation, obvious spatial heterogeneities of grassland ecosystem structure and pattern were detected in the area. By analyzing the spatial distribution of various nutrient elements’ concentrations in grassland soils along the elevation, this study revealed the spatial heterogeneities, the mechanism of pattern evolvements and the responses of spatial patterns of the different forms of nutrients to the elevation changes in grassland soils. This study also discussed the classifications of the soil organic carbon (SOC) in different grassland types, the vertical distribution patterns of various SOC forms (active organic carbon, slow organic carbon and passive organic carbon) in different grassland types as well as the spatial distribution of the nutrient contents of plant community in different grassland types. The results clarified the ecological and biogeochemical features of grasslands in terms of soil nutrients and plant nutrients, which could help to understand the evolvement rules and living matters' cycle characteristics of grassland ecosystems in Xinjiang. The study could provide the theoretical basis for vegetation restorations of damaged ecosystems and support for further protecting grassland and ecosystems. Based on field survey and laboratory analysis of samples collected from the sampling sites in the study area, the main conclusions are as follow: 1. The pH, concentrations of available nitrogen (AN), available phosphorus (AP), available potassium (AK) and organic matter (OM) in surface soils of each sampling site decreased as the soil depth increased, while concentrations of other soil elements showed fluctuation with insignificant change. On the spatial pattern, concentrations of soil AN, AP, AK, OM and iron (Fe) increased from west to east along the Kunes River. There was significantly positive correlation between altitudinal gradient and each of the other soil indexes. As the altitudinal gradient increases, concentrations between soil total N (TN) and total P (TP) increase first and then decrease with the increase of altitude, and their concentrations were highest in the middle part of the mountain. Concentrations of soil total K (TK) decreased with the increase of altitude. Soil selenium (Se) contents also increased first and then decreased with the increase of altitude, whereas Se contents in aboveground and root of plant decreased first and then increased with the increase of altitude, which showed an opposite tendency on comparison with soil selenium contents. Soil selenium content is enough for plant growth and the Se content in plants are moderate. 2. There were great differences in concentrations of soil organic carbon fractions among the soils from different grassland types. The concentration of soil active organic carbon ranged from 0.070 to 1.553 g.kg-1 with a mean value of 0.557 g.kg-1 under various grassland types. Soil active organic carbon contents increased first and then decreased with the increase of soil depth in desert steppes, while contents of soil slow carbon consistently decreased with the increase of soil depth; concentrations of both soil active and slow organic carbon increased first and then decreased with the increase of soil depth in semi-desert steppes; in mountain meadow steppes and alpine meadows, concentrations of both soil active and slow organic carbon showed a decreasing tendency with the increase of soil depth; inertia organic carbon increased first and then decreased with the increase of soil depth in desert steppe and semi-desert steppe soils; concentrations of soil inertia organic carbon decreased with the increase of soil depth in mountain meadows, mountain meadow steppes and alpine meadows. In general, concentrations of soil active organic carbon, slow organic carbon as well as inertia organic carbon concentrations followed a same order: mountain meadow >alpine meadow >mountain meadow steppe >desert steppe and semi-desert steppe. Soil active organic carbon decreased with the increase of soil depth in both types of grassland desert steppe and semi-desert steppe. This indicates that grassland soil organic carbon stability in the study area is good and beneficial for the soil organic carbon fixed storage for a long time. 3. Under community scale, R/S of various grassland types ranged from 0.3~8.6 with a mean value of 2.9. According to the ratio of R/S, it is able to estimate the underground biomass, carbon allocation and fixation of grasses in the research area. These results showed that higher grassland biodiversity index in this area have more stable system structure, which is more suitable for grazing. The grazing intensity from semi-desert grassland and desert grassland can be reduced and the grazing should be shifted to the mountain zone, which is better for grassland protection and management. 4. C contents in underground parts were lower than that in aboveground parts from the temperate steppe community. The average values of total C in plant leaves and roots were 346.1 g.kg-1 and 341.8 g.kg-1, respectively. The average values of N and P in plant leaves were 13.6 g.kg-1 and 1.7 g.kg-1, respectively. For the underground part, the average values of N and P were 9.5 g.kg-1 and 1.4 g.kg-1, respectively. By comparison with the mean N and P contents of leaves in China, N contents in the study area were lower, while the P contents were consistent with national level. In the future, we should pay more attention to the study of N nutrient. The average aboveground parts and root’s chemometrics of N/P were 7.5 and 7.1, respectively. N is a limiting factor and it should be taken into consideration for the appropriate supply nitrogen. 5. There were significant correlations among nutrients concentrations in different parts of the grassland plants. Plant C concentrations in aboveground were significantly positively correlated to plant N and K concentrations (p<0.01). Plant N was negatively correlated to C/N ratio, but significantly positively to other nutrient indexes both in the aboveground and underground parts (p<0.01). Plant P contents in aboveground parts were significantly positively correlated to plant K contents in aboveground parts and plant P contents in the underground parts (p<0.01), but significantly negatively to plant C/N ratio and N/P ratio in aboveground parts (p<0.01). |
| 学科主题 | 自然地理学 |
| 语种 | 中文 |
| 源URL | [http://ir.xjlas.org/handle/365004/14914]  |
| 专题 | 新疆生态与地理研究所_研究系统_荒漠环境研究室 |
| 作者单位 | 中科院新疆生态与地理研究所 |
| 推荐引用方式 GB/T 7714 | 马杰. 巩乃斯河流域典型草地生态学特征及土壤营养元素的空间异质性研究[D]. 北京. 中国科学院大学. 2015. |
入库方式： OAI收割
来源：新疆生态与地理研究所
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