牧压调控对高寒草甸夏季草场植被、土壤固碳能力影响的研究

NWIPB OpenIR

	牧压调控对高寒草甸夏季草场植被、土壤固碳能力影响的研究
	吴启华
学位类型	硕士
导师	李英年
	2014-05
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	高寒杂草类草甸牧压梯度群落特征植被碳密度土壤碳密度
摘要	放牧是草地最主要的利用方式之一，为此，研究者针对放牧和禁牧对植被和土壤的固碳能力的研究有较多的报道，而对高寒杂草类草甸不同放牧强度下植被、土壤碳格局分布研究涉及较少。本文监测了牧压梯度(不同放牧强度)下(禁牧(SCK)、轻度放牧(SL)、中度放牧(SM)、重度放牧(SH))高寒杂草类草甸样地土壤温湿度、土壤持水能力、植被生产力、生物多样性、土壤理化特性、植被和土壤的碳密度以及土壤呼吸和生态系统呼吸的基础上，分析了牧压梯度下相关生态环境要素的变化特征以及对植被/土壤固碳能力的影响。以期构建草地固碳作用与放牧管理的平衡模式，为草地生态系统固碳技术的管理提供科学依据。研究得到，不同放牧强度下： 1)土壤的温度、湿度年变化趋势基本相同，轻牧及禁牧条件下最高最低温度出现时间落后，年均温度稍高。土壤容重在0～10cm表层为SH最大，而在较深层次SL较大。土壤毛管持水量和最大持水量，在0～10cm表层为SL最大，而在20～40cm的较深层次则是SH较大。表现出短期放牧对表层土壤的容重和持水能力影响显著，轻牧及禁牧条件下土壤容重降低、土壤持水能力增加。 2)禾本科、莎草科和杂类草3种主要功能群的重要值变化不尽相同，随放牧强度降低禾草类植物重要值明显增加，而草地退化指示性的杂草类植物的重要值均在重牧条件下最大。物种丰富度和多样性指数均在SM最大，说明中牧有利于物种多样性的维持。 3)植被地上、地下生物总的现存碳密度和枯落物现存碳密度自大到小依次为SCK、SL、SM、SH，表现出随放牧强度的增大而降低。其植被总的净初级生产碳密度由大到小依次为SM、SL、SH、SCK，SM总的净初级生产碳密度明显高于其他放牧强度。说明中度放牧是高寒杂草类草甸较为合理的利用方式，且有较高的植被固碳能力。 4)0～40cm层次土壤有机碳密度和全氮密度均表现为禁牧条件大于放牧，说明禁牧有利于土壤碳密度的增加。而放牧条件下，随放牧强度的增大土壤碳密度稍有增大，但无显著差异。土壤碳密度在0～10cm 土壤层次SH最大，10～40cm各层次由大到小都是SCK、SH、SL、SM。说明短期放牧对土壤的碳氮密度影响不明显。 5)植物生长季土壤呼吸表现出SCK＞SM＞SH＞SL，生态系统呼吸量为SCK＞SL＞SM＞SH，净生态系统交换量表现出SCK＞SL＞SM＞SH，放牧强度增大，草地碳汇能力减弱。
其他摘要	Grazing is one of the most important practices in grassland ecosystem management. The studies about the effects on vegetation/soil carbon sequestration capacity of different grazing managements were common, while the involved studies of the alpine weedy meadow, which is mainly used for summer pasture in the Qinghai-Tibetan Plateau, was little conducted. We have carried out the experiment of different four grazing gradients (grazing enclosure-SCK, light grazing-SL, moderate grazing-SM and heavy grazing-SH) on an alpine weedy meadow since 2011. In four grazing plots, the soil temperature and moisture, soil physical-chemical properties, soil water holding capacity, vegetation production, community diversity, vegetation/soil carbon density, soil respiration and ecosystem respiration were measured during plant growing season. In order to understanding equilibrium between grassland carbon sequestration and grazing management and providing a scientific basis for the management of carbon sequestration technology, we analyzed that the variations of environment factors and vegetation/soil carbon sequestration capacity, and discussed their potential relationship in the alpine weedy meadow. The results were as follows: (1) The annual variation of soil temperature and moisture showed the similar trends under different grazing intensity, the annual average temperature was higher in SCK and SL, and the occurring time of highest and lowest temperature was delayed. The maximum of soil bulk density was in SH at 0-10 cm soil layer and in SL at soil deeper layer. Capillary water holding capacity and maximal water holding capacity were largest in SL of 0～10cm soil layer, largest in SH 20～40cm soil layer. The results indicated that the influences of grazing on soil properties was demonstrated in surface layer, and the topsoil bulk density decreased and water holding capacity increased in SCK and SL. (2) The variations of the important Value(IV) of Gramineae, Sedge and Forbs were idiosyncratic. The IV of Gramineae increased with grazing intensity decreased and the IV of Forbs was the largest in HG plots. Species diversity index and species richness were the largest in SM, showing that moderate grazing was beneficial to the maintenance of diversity. (3) The current total vegetation (including aboveground, belowground, and standing litter ) carbon content increased with grazing intensity decreased, and followed by SCK>SL>SM>SH. Annual net primary carbon production of vegetation was SM>SL>SH>SCK, and it suggested that moderate grazing was the reasonable management manner and was beneficial to the accumulation of vegetation carbon.
文献类型	学位论文
条目标识符	http://210.75.249.4/handle/363003/4023
专题	中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	吴启华. 牧压调控对高寒草甸夏季草场植被、土壤固碳能力影响的研究[D]. 北京. 中国科学院研究生院,2014.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
牧压调控对高寒草甸夏季草场植被、土壤固碳（1180KB）			开放获取	CC BY-NC-SA	请求全文