柄扁桃灌丛化荒漠草原群落组成特征及其分布机理研究

发布时间：2018-03-17 10:56

本文选题：灌丛化　切入点：荒漠草原　出处：《内蒙古大学》2015年硕士论文　论文类型：学位论文

【摘要】：荒漠草原灌丛化现象十分普遍,灌丛化对于草地群落的影响是多方面的。灌丛化会增加草地生态系统的地上、地下总生物量,但净初级生产力变化不显著,而对生物多样性的影响具有不确定性。灌丛化导致的“肥岛”效应加剧了草原生态系统中光照、热量、水分、养分的空间异质性,使得灌丛斑块与草地斑块可利用的资源格局发生变化。柄扁桃为喜光的中旱生落叶灌木,在我国的主要分布区位于内蒙古阴山山脉前山区和内蒙古伊克昭盟的鄂托克旗、乌审旗到陕西北部长城沿线的沙漠中。原本分布于干旱区山地和沙漠的柄扁桃进入了苏尼特右旗西南部的半干旱荒漠草原,形成了一片面积约50km2的柄扁桃灌丛景观。在与周围没有柄扁桃分布区域大地形、气候条件一致的情况下,导致柄扁桃只在特定区域分布的原因应为土壤因子。在查阅资料及实地考察绘制柄扁桃分布区图的基础上,对有、无柄扁桃分布的区域分别进行了植被群落调查和土壤机械组成分析,得到以下结论：1、柄扁桃在草原区分布的生态效应柄扁桃从原本分布的干旱区山地,进入气候相对温和的半干旱高平原沙地、荒漠区域,在荒漠草原群落中占据了一定的空间和资源,形成了灌丛化荒漠草原景观。灌木植物对土壤水分和养分的收集和沉积,增加了土壤资源的空间异质性,从而产生了灌丛占有更多水分和养分的“肥岛”效应；柄扁桃在荒漠草原中的扩展与其冠层下土壤异质性的增强之间存在着正反馈作用。正是这种正反馈作用加强了灌木物种对自然环境扰动的抵抗能力,使其在灌丛化草原生态系统中的生存更加稳固。2、有、无柄扁桃分布区群落结构特征苏尼特草原属于温带荒漠草原带,位于苏尼特右旗西南部的是以小针茅建群的荒漠草原,灌丛化现象普遍。柄扁桃分布区群落无论是灌木还是草本植物的物种数都较分布区周围无柄扁桃分布的群落多。柄扁桃分布于小针茅荒漠草原,形成了柄扁桃灌丛化景观。在柄扁桃分布区内,小针茅的频度(0.54)较无柄扁桃分布区小针茅频度(0.94)低,亚优势种多根葱和糙隐子草频度差异不大(有柄扁桃分别为：0.4、0.37,无柄扁桃分别为：0.37、0.3)；有柄扁桃分布区频度在0.1以上的植物种更多,但群落稳定性较无柄扁桃分布区稍差。3、柄扁桃分布在荒漠草原区的机制由于灌丛对风沙的截留,使得柄扁桃灌丛下通常形成沙堆,内部保存了水分以供植株利用。柄扁桃分布区的地表通常覆盖有几厘米至十几厘米的砂土,砂粒含量达到97.01%,该层砂土使得地表水分迅速下渗,减少地表蒸发量。无柄扁桃分布区中层和底层土壤含有更高含量的粉粒和粘粒,含有大量石砾,淀积层较浅,土壤紧实度极大,有大量降雨时常形成细小的地表径流,植物根系只能分布在0～30cm土层,很难向下生长。土壤机械组成的差异造成土壤中水分分布的差异,柄扁桃灌丛化增强了这种差异,是柄扁桃分布在特定的区域的重要原因。
[Abstract]:Desert shrub grassland phenomenon is very common, in many aspects for the effects of grassland communities. Shrubs will increase the grassland ecological system on the ground, underground biomass, but the changes of net primary productivity is not significant, but with uncertain effects on biodiversity. Shrub in "fertile island" the effect of intensified grassland ecosystem in the light, heat, water, nutrient spatial heterogeneity, the shrub patches and patch available resources. Changes in the pattern of prunuspedunculata light in xeric deciduous shrubs, in our country the main distribution area is located in the Inner Mongolia mountains and the Yinshan Mountains before Inner Mongolia s Etuokeqi, Wushenqi to northern Shaanxi along the the Great Wall in the desert. Originally distributed in Arid Mountainous and desert prunuspedunculata in semi arid desert grassland Suniteyou southwest, forming a one-sided Area of about 50km2 of prunuspedunculata shrub landscape in and around. No prunuspedunculata distribution of large terrain area, climate conditions are same, resulting in prunuspedunculata should only be for the soil factor in the regional distribution of specific reasons. After the inspection and investigation of distribution of prunuspedunculata area, there is no handle area of. Almond distribution were composed of vegetation investigation and soil mechanical analysis, obtained the following conclusions: 1, prunuspedunculata in grassland area distribution and ecological effects of prunuspedunculata from the original distribution of the mountainous regions in arid areas, into the relatively mild climate of semi arid high plains sandy desert region, to occupy a certain space and resources in desert steppe in the community, the formation of desert steppe landscape shrub. Collection and deposition of shrubs on soil water and nutrients, increase the spatial heterogeneity of soil resources, resulting in more water for shrub And nutrient of "fertile island" effect; between reinforced soil heterogeneity of prunuspedunculata expansion in the desert steppe in its canopy has a positive feedback effect. It is the positive feedback effect of shrub species on the natural environment to strengthen the ability to resist disturbance, so that in the thicketization of grassland ecosystem in the survival of more stable.2, sessile community distribution characteristics of almond Sunite grassland belongs to the temperate desert steppe zone, located in the southwest of Suniteyou district is a small group of Stipa built desert steppe, shrub phenomenon common. Prunuspedunculata distribution area regardless of the number of species of shrub communities around or herbaceous plants are distributed free zone community distribution of almond handle. Prunuspedunculata distribution in Stipa klemenzii desert steppe, the formation of prunuspedunculata shrub landscape. In prunuspedunculata distribution area, the frequency of Stipa klemenzii (0.54) than in non prunuspedunculata distribution area of Stipa klemenzii frequency Low degree (0.94), sub dominant species Allium polyrrhizum and c.squarrosa frequency difference (with pedunculata were: 0.4,0.37, no prunuspedunculata respectively: 0.37,0.3); species prunuspedunculata distribution frequency in more than 0.1 more, but less stability of the community of prunuspedunculata distribution area of less.3. Prunuspedunculata distribution in the desert steppe region due to the mechanisms of interception of sand shrubs, shrubs usually form makes prunuspedunculata sand, save water plant for internal use. The surface area of prunuspedunculata usually covered with sand a few centimeters to more than a dozen centimeters, sand content reached 97.01%, the sand layer makes the surface water quickly infiltration, reduce surface evaporation. No silt and clay prunuspedunculata distribution area of the middle and bottom soil contains higher content, contains a lot of gravel, the deposition layer is shallow, the soil compaction is great, have a lot of rain often shaped into small diameter surface The root system of plants can only distribute in the 0 ~ 30cm soil layer. It is difficult to grow downward. The difference of soil mechanical composition results in the difference of soil moisture distribution. The almond Bush shrub increased the difference, which is an important reason for the distribution of Prunus communis in a specific area.

【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812

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