不同载畜率对短花针茅荒漠草原土壤风蚀的影响及作用机制

发布时间：2018-04-24 08:05

本文选题：荒漠草原 + 载畜率　；参考：《内蒙古农业大学》2016年博士论文

【摘要】：荒漠草原是旱生性最强和对外界干扰最敏感的草原生态系统,承受着严重的风蚀和放牧双重胁迫。开展荒漠草原不同放牧利用强度对风蚀过程影响的研究,可以阐明草地放牧对干旱区风蚀过程的影响及其作用机制,并对科学规划放牧制度、合理制定草地区域保护政策具有重要意义。以内蒙古短花针茅(Stipa breviflora)草原为研究对象,在连续开展11年的随机区组放牧样地(设置4个载畜率0.93、1.82、2.71、0sheep/hm2/year)布设BSNE集沙仪,通过2年(2013年4月——2015年4月)共4个采样期的监测,研究载畜率与风沙通量的定量关系及风蚀物粒度特征；并通过取原状土样进行室内风洞吹蚀试验,研究载畜率与风蚀速率的定量关系及估测不同载畜率荒漠草原风蚀总量。研究结果表明：(1)荒漠草原载畜率对风沙通量影响显著：荒漠草原区,日平均风沙通量在2.38-31.39 g/m/d之间,平均为16.00 g/m/d(所有季节均值)；载畜率对风沙通量有显著影响,随载畜率的增强,风沙通量逐渐增加；生长季风沙通量明显小于非生长季；载畜率和季节对风沙通量的影响存在交互效应,非生长季节不同载畜率间的风沙通量差异远小于生长季载畜率间的差异。(2)不同季节和载畜率对荒漠草原风沙流结构影响各异：生长季风沙流结构垂向分布符合经典的风沙流指数递减函数,而非生长季,该函数拟合效果较差,可能由于植被留茬高度的差异,风沙流结构表现不同的规律；生长季,载畜率主要增加近地表含沙量,非生长季,50 cm以上含沙量明显增加。垂直高度较高的风沙流,主要受季节控制,载畜率影响较小,载畜率间的风沙流结构的差异主要体现近地表层次。(3)荒漠草原风沙沉积物粒径分选作用与垂向分布结构明显：风沙沉积物颗粒250 μm的土壤颗粒为主,占所有沉积物颗粒的85%以上；随着高度增加,风蚀物颗粒组成逐渐变细,风蚀作用下,土壤表土中D50颗粒(50μm)最为活跃,而D50-125(50-125 μm)和D125-250颗粒(125-250 μm)在表土中有相应的聚集现象；重度和中度放牧区,50μm颗粒富集比随高度增加而增加的规律较稳定,而CK和LG区,在50 cm以上,富集比随高度增加不再变化,基本处于同一水平；放牧导致更多的细颗粒在更高垂直高度累计,这一层次属于悬移颗粒,有可能传递更远的距离,对草地营养损失可能影响更大。(4)风沙沉积物C、N等元素含量水平输移垂直分布梯度明显：四子王旗荒漠草原区,每1000kg风蚀沉积物,含有全碳30.90kg、全氮2.87 kg,风蚀过程带走大量的土壤营养物质。沉积物的养分含量与载畜率有直接的关系,对照区保留有更丰富的营养,风沙营养水平更高,随着载畜率的增强,沉积物全碳和全氮含量均逐渐降低；近地表沙尘营养含量最低,但随高度增加,在50 cm高度沉积物营养基本达到峰值的95%,然后随高度变化较少。风沙沉积物垂直高度和载畜率之间对营养含量的影响存在交互效应,CK和LG处理,不同高度间沉积物养分水平差异较小,MG和HG区,不同高度沉积物养分水平差异较大,高载畜率风沙沉积物营养水平有更显著垂直梯度分布,特别是近地表层次。沉积物C/N比为平均为10.88,但C/N计量关系受载畜率影响显著,随载畜率增加,沉积物中全碳含量下降更显著,使得C/N比表现逐渐下降的趋势；风蚀带走了土壤中最富营养的部分,与表土相比,几乎所有的元素含量在沉积物中都表现更高的富集浓度。(5)载畜率增大了荒漠草原风沙沉积物营养的流失：营养通量是养分含量和风蚀颗粒质量的综合反映；荒漠草原区,非生长季养全碳和全氮通量分别占到全年通量的68%和65%；随载畜率增大,营养通量逐渐增加,重度放牧区平均营养通量是对照区的1.8倍,重度放牧区风蚀物营养水平低但有较高的营养通量,风蚀和放牧加剧了土壤养分的进一步流失。(6)基于风洞吹蚀方法的不同载畜率风蚀强度估测：基于风洞试验并结合试验期间每10分钟详细风速风频数据分析,风蚀强度随载畜率的增大而增大,CK区风蚀强度115.24 t/km2. Year,重度放牧区达到648.95 t/km2. Year,与典型草原的重度放牧利用相比,风蚀强度高出10倍。放牧活动导致的土壤践踏强度增加及可食性牧草减少是导致风蚀强度增加的共同因素,但其作用过程并非线性关系。(7)放牧-风蚀耦合影响荒漠草原稳定性的机制：放牧利用是草地管理的主要方式,相对于典型草原和草甸草原的退化原因,风蚀和放牧过程的耦合,是导致荒漠草原草地退化的重要原因,细颗粒损失、带走更丰富的营养、放牧区更活跃的风沙流结构,这些都是荒漠草原草地退化的重要驱动力。近年来实施的一系列草地禁牧政策和措施,在推动草原生态环境改善方面发挥了积极作用,在一定程度抑制了草地风蚀和退化趋势,说明政府在近年来实施的草地管理方略是行之有效的,通过宏观的调控和政策引导,草地风蚀与荒漠化可以得到有效控制。在未来草地利用中,应当继续实施草地保护的策略和措施,促进草地生态环境的进一步好转。
[Abstract]:In this paper , the effects of grazing intensity on wind erosion in desert steppe were studied . The effects of grazing intensity on wind erosion were studied .
In this paper , the quantitative relationship between the rate of livestock and wind erosion and the total wind erosion of desert steppe were studied by taking undisturbed soil samples . The results show that : ( 1 ) The effect of livestock rate on wind - sand flux in desert steppe is significant : ( 1 ) The average wind - sand flux of desert steppe is 2.38 - 31.39 g / m / d , the average is 16.00 g / m / d ( all seasonal mean ) ;
There was a significant influence on the flux of wind and sand , and the flux of wind and sand increased gradually with the increase of livestock rate .
the growth monsoon flux is obviously smaller than that of non - growing season ;
( 2 ) The vertical distribution of sand flow in different seasons is consistent with the classical wind - sand flow index decreasing function , but the non - growing season , the function fitting effect is poor , possibly due to the difference of stubble height of vegetation , the wind - sand flow structure shows different rules ;
In the growing season , the rate of livestock raising mainly increased the sediment content near the surface , the non - growing season , and the sediment content over 50 cm increased significantly . The vertical height was higher than that at 50 cm . The difference of wind and sand flow structure was mainly in the near surface level .
The D50 particles ( 50 渭m ) in the soil surface soil were most active with the increase of the height , and the D50 - 125 ( 50 - 125 渭m ) and D125 - 250 ( 125 - 250 渭m ) had corresponding aggregation in the topsoil .
In severe and moderate grazing areas , the enrichment ratio of 50 渭m particles increased with the increase of height , while CK and LG were more than 50 cm .
( 4 ) There is a direct relation between the nutrient content of sediment and the rate of livestock and livestock , and the nutrient content of sediment is higher than that in control area , and the total carbon and total nitrogen content of sediments are gradually decreased with the increase of livestock .
There was a significant difference between the vertical height of sediment at 50 cm and the level of nutrient in sediment at 50 cm . There was a significant difference between the vertical height of sediment and the rate of nutrient in sediment .
Wind erosion took away the most nutritious part of the soil , almost all of the elements showed a higher concentration in sediment than the topsoil . ( 5 ) The livestock rate increased the loss of nutrients in the desert steppe . The nutrient flux was a comprehensive reflection of nutrient content and the quality of wind erosion particles ;
The total carbon and total nitrogen fluxes accounted for 68 % and 65 % of the total flux throughout the year .
According to wind tunnel test and combined with the test period , the wind erosion intensity is increased with the increase of the carrier rate , and the wind erosion intensity of CK region is 11.24 t / km2 . In Year , the severe grazing area reached 648 . 95 t / km2 . In recent years , the grassland management strategy and measures have been put into practice , which is an important driving force for grassland degradation in desert steppe .

【学位授予单位】：内蒙古农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S812

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