發(fā)布時(shí)間：2018-04-24 08:05

  本文選題：荒漠草原 + 載畜率��； 參考：《內(nèi)蒙古農(nóng)業(yè)大學(xué)》2016年博士論文

【摘要】：荒漠草原是旱生性最強(qiáng)和對外界干擾最敏感的草原生態(tài)系統(tǒng),承受著嚴(yán)重的風(fēng)蝕和放牧雙重脅迫。開展荒漠草原不同放牧利用強(qiáng)度對風(fēng)蝕過程影響的研究,可以闡明草地放牧對干旱區(qū)風(fēng)蝕過程的影響及其作用機(jī)制,并對科學(xué)規(guī)劃放牧制度、合理制定草地區(qū)域保護(hù)政策具有重要意義。以內(nèi)蒙古短花針茅(Stipa breviflora)草原為研究對象,在連續(xù)開展11年的隨機(jī)區(qū)組放牧樣地(設(shè)置4個載畜率0.93、1.82、2.71、0sheep/hm2/year)布設(shè)BSNE集沙儀,通過2年(2013年4月——2015年4月)共4個采樣期的監(jiān)測,研究載畜率與風(fēng)沙通量的定量關(guān)系及風(fēng)蝕物粒度特征；并通過取原狀土樣進(jìn)行室內(nèi)風(fēng)洞吹蝕試驗(yàn),研究載畜率與風(fēng)蝕速率的定量關(guān)系及估測不同載畜率荒漠草原風(fēng)蝕總量。研究結(jié)果表明：(1)荒漠草原載畜率對風(fēng)沙通量影響顯著：荒漠草原區(qū),日平均風(fēng)沙通量在2.38-31.39 g/m/d之間,平均為16.00 g/m/d(所有季節(jié)均值)；載畜率對風(fēng)沙通量有顯著影響,隨載畜率的增強(qiáng),風(fēng)沙通量逐漸增加；生長季風(fēng)沙通量明顯小于非生長季；載畜率和季節(jié)對風(fēng)沙通量的影響存在交互效應(yīng),非生長季節(jié)不同載畜率間的風(fēng)沙通量差異遠(yuǎn)小于生長季載畜率間的差異。(2)不同季節(jié)和載畜率對荒漠草原風(fēng)沙流結(jié)構(gòu)影響各異：生長季風(fēng)沙流結(jié)構(gòu)垂向分布符合經(jīng)典的風(fēng)沙流指數(shù)遞減函數(shù),而非生長季,該函數(shù)擬合效果較差,可能由于植被留茬高度的差異,風(fēng)沙流結(jié)構(gòu)表現(xiàn)不同的規(guī)律；生長季,載畜率主要增加近地表含沙量,非生長季,50 cm以上含沙量明顯增加。垂直高度較高的風(fēng)沙流,主要受季節(jié)控制,載畜率影響較小,載畜率間的風(fēng)沙流結(jié)構(gòu)的差異主要體現(xiàn)近地表層次。(3)荒漠草原風(fēng)沙沉積物粒徑分選作用與垂向分布結(jié)構(gòu)明顯：風(fēng)沙沉積物顆粒250 μm的土壤顆粒為主,占所有沉積物顆粒的85%以上；隨著高度增加,風(fēng)蝕物顆粒組成逐漸變細(xì),風(fēng)蝕作用下,土壤表土中D50顆粒(50μm)最為活躍,而D50-125(50-125 μm)和D125-250顆粒(125-250 μm)在表土中有相應(yīng)的聚集現(xiàn)象；重度和中度放牧區(qū),50μm顆粒富集比隨高度增加而增加的規(guī)律較穩(wěn)定,而CK和LG區(qū),在50 cm以上,富集比隨高度增加不再變化,基本處于同一水平；放牧導(dǎo)致更多的細(xì)顆粒在更高垂直高度累計(jì),這一層次屬于懸移顆粒,有可能傳遞更遠(yuǎn)的距離,對草地營養(yǎng)損失可能影響更大。(4)風(fēng)沙沉積物C、N等元素含量水平輸移垂直分布梯度明顯：四子王旗荒漠草原區(qū),每1000kg風(fēng)蝕沉積物,含有全碳30.90kg、全氮2.87 kg,風(fēng)蝕過程帶走大量的土壤營養(yǎng)物質(zhì)。沉積物的養(yǎng)分含量與載畜率有直接的關(guān)系,對照區(qū)保留有更豐富的營養(yǎng),風(fēng)沙營養(yǎng)水平更高,隨著載畜率的增強(qiáng),沉積物全碳和全氮含量均逐漸降低；近地表沙塵營養(yǎng)含量最低,但隨高度增加,在50 cm高度沉積物營養(yǎng)基本達(dá)到峰值的95%,然后隨高度變化較少。風(fēng)沙沉積物垂直高度和載畜率之間對營養(yǎng)含量的影響存在交互效應(yīng),CK和LG處理,不同高度間沉積物養(yǎng)分水平差異較小,MG和HG區(qū),不同高度沉積物養(yǎng)分水平差異較大,高載畜率風(fēng)沙沉積物營養(yǎng)水平有更顯著垂直梯度分布,特別是近地表層次。沉積物C/N比為平均為10.88,但C/N計(jì)量關(guān)系受載畜率影響顯著,隨載畜率增加,沉積物中全碳含量下降更顯著,使得C/N比表現(xiàn)逐漸下降的趨勢；風(fēng)蝕帶走了土壤中最富營養(yǎng)的部分,與表土相比,幾乎所有的元素含量在沉積物中都表現(xiàn)更高的富集濃度。(5)載畜率增大了荒漠草原風(fēng)沙沉積物營養(yǎng)的流失：營養(yǎng)通量是養(yǎng)分含量和風(fēng)蝕顆粒質(zhì)量的綜合反映；荒漠草原區(qū),非生長季養(yǎng)全碳和全氮通量分別占到全年通量的68%和65%；隨載畜率增大,營養(yǎng)通量逐漸增加,重度放牧區(qū)平均營養(yǎng)通量是對照區(qū)的1.8倍,重度放牧區(qū)風(fēng)蝕物營養(yǎng)水平低但有較高的營養(yǎng)通量,風(fēng)蝕和放牧加劇了土壤養(yǎng)分的進(jìn)一步流失。(6)基于風(fēng)洞吹蝕方法的不同載畜率風(fēng)蝕強(qiáng)度估測：基于風(fēng)洞試驗(yàn)并結(jié)合試驗(yàn)期間每10分鐘詳細(xì)風(fēng)速風(fēng)頻數(shù)據(jù)分析,風(fēng)蝕強(qiáng)度隨載畜率的增大而增大,CK區(qū)風(fēng)蝕強(qiáng)度115.24 t/km2. Year,重度放牧區(qū)達(dá)到648.95 t/km2. Year,與典型草原的重度放牧利用相比,風(fēng)蝕強(qiáng)度高出10倍。放牧活動導(dǎo)致的土壤踐踏強(qiáng)度增加及可食性牧草減少是導(dǎo)致風(fēng)蝕強(qiáng)度增加的共同因素,但其作用過程并非線性關(guān)系。(7)放牧-風(fēng)蝕耦合影響荒漠草原穩(wěn)定性的機(jī)制：放牧利用是草地管理的主要方式,相對于典型草原和草甸草原的退化原因,風(fēng)蝕和放牧過程的耦合,是導(dǎo)致荒漠草原草地退化的重要原因,細(xì)顆粒損失、帶走更豐富的營養(yǎng)、放牧區(qū)更活躍的風(fēng)沙流結(jié)構(gòu),這些都是荒漠草原草地退化的重要驅(qū)動力。近年來實(shí)施的一系列草地禁牧政策和措施,在推動草原生態(tài)環(huán)境改善方面發(fā)揮了積極作用,在一定程度抑制了草地風(fēng)蝕和退化趨勢,說明政府在近年來實(shí)施的草地管理方略是行之有效的,通過宏觀的調(diào)控和政策引導(dǎo),草地風(fēng)蝕與荒漠化可以得到有效控制。在未來草地利用中,應(yīng)當(dāng)繼續(xù)實(shí)施草地保護(hù)的策略和措施,促進(jìn)草地生態(tài)環(huán)境的進(jìn)一步好轉(zhuǎn)。
[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 .

【學(xué)位授予單位】：內(nèi)蒙古農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：S812

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本文編號：1795824