發(fā)布時(shí)間：2018-03-09 18:40

  本文選題：退耕草地　切入點(diǎn)：合理放牧　出處：《中國農(nóng)業(yè)科學(xué)院》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：黃土高原是我國土壤侵蝕嚴(yán)重區(qū)域之一,自1999年實(shí)施退耕還林(草)以來該區(qū)生態(tài)環(huán)境得到較大改善,但同時(shí)也帶來一些社會、經(jīng)濟(jì)問題。在該區(qū)采取必要措施在保護(hù)生態(tài)環(huán)境的同時(shí)又能促使農(nóng)民增收的顯得尤為重要。本研究選擇黃土高原渭北旱原坡地,建立退耕草地放牧,退耕草地不放牧和傳統(tǒng)農(nóng)耕地三種處理的對比試驗(yàn)小區(qū),定量研究了在退耕草地開展合理放牧在減少土壤呼吸和土壤侵蝕方面的作用及其影響因素。本試驗(yàn)在建立的三種試驗(yàn)小區(qū),利用LI-8100碳通量自動測量儀原位監(jiān)測植物生長期(4~9月)和植物非生長期(10~12月)三種處理土壤CO2排放速率的變化,同時(shí)利用時(shí)域反射儀(TDR 300)測定表層0~10cm土壤含水量,用地溫表測定2cm和5cm表層土壤的溫度。利用環(huán)境放射性核素7Be示蹤技術(shù),監(jiān)測較大降雨事件引起的土壤侵蝕速率,同時(shí)取樣測定侵蝕區(qū)土壤有機(jī)碳含量,比較不同處理小區(qū)侵蝕導(dǎo)致的土壤有機(jī)碳流失量。結(jié)果表明:(1)在植物生長期3種處理土壤CO2平均排放速率大小順序?yàn)?退耕草地[3.69±0.39μmol/(m2?s)]退耕草地放牧[3.00±0.44μmol/(m2?s)]傳統(tǒng)農(nóng)耕地[1.99±0.22μmol/(m2?s)],且3種處理土壤CO2平均排放速率有顯著性差異(P0.05);坡耕地退耕還草后土壤CO2排放增加了85%,合理放牧使退耕草地土壤CO2排放量減少了19%;在植物生長期,放牧后退耕草地土壤CO2排放減少主要與動物踩踏引起土壤容重明顯增加及草類植被地上部分向土壤中輸入的有機(jī)碳的減少有關(guān)。在植物非生長期,3種處理土壤CO2平均排放速率大小順序?yàn)?退耕草地[0.76±0.21μmol/(m2?s)]傳統(tǒng)農(nóng)耕地[0.68±0.13μmol/(m2?s)]退耕草地放牧[0.51±0.13μmol/(m2?s)],但3種處理土壤CO2平均排放速率無顯著性差異(P0.05);植物非生長期合理放牧對退耕草地土壤呼吸影響不大,土壤呼吸主要受土壤溫度的影響。(2)在植物生長期,水分、溫度影響因子無法解釋三種處理間土壤CO2排放差異;在植物非生長期溫度變化可以解釋三種處理間土壤呼吸變化的50%以上,尤其是放牧地,溫度變化可解釋土壤呼吸變化的86.61%。(3)在退耕草地實(shí)施合理放牧可有效減少土壤侵蝕和土壤有機(jī)碳的流失。兩次較大降雨事件后退耕草地放牧相較于退耕草地不放牧土壤侵蝕量平均減少了75%,土壤有機(jī)碳流失量平均減少了78%。合理放牧期間動物的踩踏作用引起草地土壤容重的增加是退耕草地土壤侵蝕減少的主要原因。本研究結(jié)果揭示,在我國黃土高原和類似的退耕還草地區(qū),在植物生長期開展合理放牧既可以促進(jìn)當(dāng)?shù)匦竽翗I(yè)生產(chǎn),又能有效控制土壤侵蝕,減少土壤CO2排放;在植物非生長期圍欄禁牧,用飼料喂養(yǎng)牲畜,可以減輕草地負(fù)擔(dān),有利于牧草的恢復(fù)生長,是一種值得探究的退耕草地可持續(xù)發(fā)展管理模式。
[Abstract]:The Loess Plateau is one of the serious areas of soil erosion in China. Since 1999, the ecological environment of this area has been greatly improved, but at the same time it has brought some societies. Economic problems. It is particularly important to take necessary measures to protect ecological environment and increase farmers' income in this area. A comparative experimental plot of three treatments, the non-grazing and the traditional agricultural land, of returning cultivated grassland, The effect of rational grazing on reducing soil respiration and soil erosion and its influencing factors were studied quantitatively. The change of soil CO2 emission rate was monitored by using LI-8100 carbon flux automatic measuring instrument in situ during plant growth period (4 ~ September) and plant non-growth period (10 ~ December). The soil water content of 0 ~ 10 cm surface layer was measured by time domain reflectometer (TDR 300). The soil erosion rate caused by heavy rainfall events was monitored by using the environmental radionuclide 7Be tracer technique, and the soil organic carbon content was measured by sampling. The soil organic carbon loss caused by soil erosion in different plots was compared. The results showed that the average CO2 emission rate of the three treatments in plant growth stage was in the order of returning farmland to grassland [3.69 鹵0.39 渭 mol / m ~ (2)]? (3. 00 鹵0. 44 渭 mol / m ~ (2)? Traditional farming land [1.99 鹵0.22 渭 mol / m ~ (2)? The average CO2 emission rate of the three treatments was significantly different (P0.05N), the soil CO2 emission increased by 85% after the conversion of sloping farmland to grass, and the soil CO2 emission decreased by 19% by rational grazing. The decrease of soil CO2 emission after grazing was mainly related to the increase of soil bulk density caused by animal stampede and the decrease of organic carbon input from the aboveground part of grass vegetation to soil. The order of the average emission rate is: returning grassland [0.76 鹵0.21 渭 mol / m ~ 2]? Traditional farming land [0.68 鹵0.13 渭 mol / m ~ (2)? S) [0.51 鹵0.13 渭 mol / m ~ (2) 路m ~ (2)] for grassland grazing [0.51 鹵0.13 渭 mol / s]? However, there was no significant difference in the average CO2 emission rate among the three treatments (P 0.05), and reasonable grazing had little effect on soil respiration in returning grassland, and soil respiration was mainly affected by soil temperature. The difference of soil CO2 emission between the three treatments could not be explained by the temperature influencing factors, and more than 50% of the changes of soil respiration between the three treatments, especially in grazing land, could be explained by the temperature change in the non-growth period of plants. Soil erosion and soil organic carbon loss can be effectively reduced by rational grazing in return grassland, which can be explained by temperature change. 86.61% of soil respiration change. Two heavy rainfall events compared with non-grazing grassland after two heavy rainfall events, conversion grassland grazing can reduce soil erosion and soil organic carbon loss. Soil erosion decreased 75%, soil organic carbon loss decreased 78%. The increase of soil bulk density caused by animal stampede during reasonable grazing was the main reason of soil erosion reduction. In the Loess Plateau of China and similar areas of returning farmland to grass, reasonable grazing during plant growth period can not only promote local animal husbandry production, but also effectively control soil erosion and reduce soil CO2 emission. Feeding livestock with fodder can lighten the burden of grassland and is beneficial to the recovery and growth of forage grass. It is a sustainable development management mode of grassland which is worth exploring.
【學(xué)位授予單位】：中國農(nóng)業(yè)科學(xué)院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：S812.2

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