本文選題：灌叢化　切入點：荒漠草原　出處：《內(nèi)蒙古大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：荒漠草原灌叢化現(xiàn)象十分普遍,灌叢化對于草地群落的影響是多方面的。灌叢化會增加草地生態(tài)系統(tǒng)的地上、地下總生物量,但凈初級生產(chǎn)力變化不顯著,而對生物多樣性的影響具有不確定性。灌叢化導(dǎo)致的“肥島”效應(yīng)加劇了草原生態(tài)系統(tǒng)中光照、熱量、水分、養(yǎng)分的空間異質(zhì)性,使得灌叢斑塊與草地斑塊可利用的資源格局發(fā)生變化。柄扁桃為喜光的中旱生落葉灌木,在我國的主要分布區(qū)位于內(nèi)蒙古陰山山脈前山區(qū)和內(nèi)蒙古伊克昭盟的鄂托克旗、烏審旗到陜西北部長城沿線的沙漠中。原本分布于干旱區(qū)山地和沙漠的柄扁桃進(jìn)入了蘇尼特右旗西南部的半干旱荒漠草原,形成了一片面積約50km2的柄扁桃灌叢景觀。在與周圍沒有柄扁桃分布區(qū)域大地形、氣候條件一致的情況下,導(dǎo)致柄扁桃只在特定區(qū)域分布的原因應(yīng)為土壤因子。在查閱資料及實地考察繪制柄扁桃分布區(qū)圖的基礎(chǔ)上,對有、無柄扁桃分布的區(qū)域分別進(jìn)行了植被群落調(diào)查和土壤機(jī)械組成分析,得到以下結(jié)論：1、柄扁桃在草原區(qū)分布的生態(tài)效應(yīng)柄扁桃從原本分布的干旱區(qū)山地,進(jìn)入氣候相對溫和的半干旱高平原沙地、荒漠區(qū)域,在荒漠草原群落中占據(jù)了一定的空間和資源,形成了灌叢化荒漠草原景觀。灌木植物對土壤水分和養(yǎng)分的收集和沉積,增加了土壤資源的空間異質(zhì)性,從而產(chǎn)生了灌叢占有更多水分和養(yǎng)分的“肥島”效應(yīng)；柄扁桃在荒漠草原中的擴(kuò)展與其冠層下土壤異質(zhì)性的增強(qiáng)之間存在著正反饋作用。正是這種正反饋作用加強(qiáng)了灌木物種對自然環(huán)境擾動的抵抗能力,使其在灌叢化草原生態(tài)系統(tǒng)中的生存更加穩(wěn)固。2、有、無柄扁桃分布區(qū)群落結(jié)構(gòu)特征蘇尼特草原屬于溫帶荒漠草原帶,位于蘇尼特右旗西南部的是以小針茅建群的荒漠草原,灌叢化現(xiàn)象普遍。柄扁桃分布區(qū)群落無論是灌木還是草本植物的物種數(shù)都較分布區(qū)周圍無柄扁桃分布的群落多。柄扁桃分布于小針茅荒漠草原,形成了柄扁桃灌叢化景觀。在柄扁桃分布區(qū)內(nèi),小針茅的頻度(0.54)較無柄扁桃分布區(qū)小針茅頻度(0.94)低,亞優(yōu)勢種多根蔥和糙隱子草頻度差異不大(有柄扁桃分別為：0.4、0.37,無柄扁桃分別為：0.37、0.3)；有柄扁桃分布區(qū)頻度在0.1以上的植物種更多,但群落穩(wěn)定性較無柄扁桃分布區(qū)稍差。3、柄扁桃分布在荒漠草原區(qū)的機(jī)制由于灌叢對風(fēng)沙的截留,使得柄扁桃灌叢下通常形成沙堆,內(nèi)部保存了水分以供植株利用。柄扁桃分布區(qū)的地表通常覆蓋有幾厘米至十幾厘米的砂土,砂粒含量達(dá)到97.01%,該層砂土使得地表水分迅速下滲,減少地表蒸發(fā)量。無柄扁桃分布區(qū)中層和底層土壤含有更高含量的粉粒和粘粒,含有大量石礫,淀積層較淺,土壤緊實度極大,有大量降雨時常形成細(xì)小的地表徑流,植物根系只能分布在0～30cm土層,很難向下生長。土壤機(jī)械組成的差異造成土壤中水分分布的差異,柄扁桃灌叢化增強(qiáng)了這種差異,是柄扁桃分布在特定的區(qū)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.

【學(xué)位授予單位】：內(nèi)蒙古大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S812

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