發(fā)布時間：2018-07-05 12:38

  本文選題：黃土高原 + 土壤水分��； 參考：《西北農(nóng)林科技大學(xué)》2015年碩士論文

【摘要】：黃土丘陵地區(qū)人工林地普遍存在土壤干化現(xiàn)象,并且隨著林木年齡的增加,干化現(xiàn)象出現(xiàn)逐年加重的趨勢。為了探索半干旱區(qū)典型覆蓋措施下土壤水分的恢復(fù)能力,本文以修復(fù)林地干化土壤水分和防控林地土壤永久性干層為目標(biāo),采用野外大型土柱和大田覆蓋的方法,通過定位監(jiān)測和實地取樣調(diào)查相結(jié)合的方法監(jiān)測了土壤水分在生育期和非生育期內(nèi)的變化規(guī)律,闡釋了山地林地土壤典型覆蓋下的自然修復(fù)能力,獲得以下結(jié)果:1)在棗樹生育期觀測野外大型土柱試驗證明,受降雨的影響,干化土壤水分逐月呈現(xiàn)遞增趨勢,但不同覆蓋措施下土壤水分的增加有所區(qū)別,到9月份時,薄膜覆蓋㧐碎樹枝覆蓋㧐裸地㧐生草覆蓋(早熟禾)。生草覆蓋與裸地相比,裸地的含水率高于生草覆蓋的,說明裸地在當(dāng)?shù)剌^生草覆蓋有利于土壤水分的恢復(fù)。三種無植物生長的典型覆蓋處理下土壤儲水增量隨著時間的變化呈直線上升的關(guān)系,有植物種植的處理中(早熟禾),土壤儲水增量與時間呈非線性關(guān)系。不同覆蓋下土壤水分垂直變化不同,隨著土層深度的增加,變異系數(shù)逐漸減小,生草覆蓋(早熟禾)和裸地在200 cm以下,基本達(dá)到穩(wěn)定,碎樹枝覆蓋在240 cm以下達(dá)到穩(wěn)定,薄膜蓋在340 cm以下達(dá)到穩(wěn)定。2)大田試驗觀測得出的幾種典型覆蓋措施其對土壤影響規(guī)律與土柱試驗得出的規(guī)律一致,即仍然表現(xiàn)出地膜覆蓋碎樹枝覆蓋裸地生草覆蓋的順序。但由于大田試驗有棗樹生長耗水的原因,表現(xiàn)出幾種覆蓋措施下的土壤含水量均低于土柱試驗結(jié)果,經(jīng)過雨季后的土壤水分修復(fù)深度也較小,裸地和生草覆蓋對土壤水分的修復(fù)深度達(dá)150 cm左右,碎樹枝覆蓋對土壤水分的修復(fù)深度達(dá)200 cm,薄膜覆蓋對土壤水分的修復(fù)深度最大,超過260 cm。3)通過大型土柱試驗在非生育期內(nèi)土壤水分的觀測,發(fā)現(xiàn)冬季是一年中土壤水分損失的最關(guān)鍵時期,裸地在0-230 cm范圍土壤水分由16.88%減少到10.42%;生草覆蓋在0-220 cm范圍土壤水分由14.67%減少到11.35%;碎樹枝覆蓋在0-150cm范圍土壤水分由18.77%減少到14.61%;薄膜覆蓋0-300 cm范圍土壤水分由20.51%減少到18.02%;土壤水分損失的深度分別為230 cm、220 cm、150 cm和300 cm。但是裸地和生草覆蓋下的土壤水分幾乎沒有下滲運移,碎樹枝覆蓋和薄膜覆蓋在上部土壤水分降低同時還有明顯的下滲現(xiàn)象,碎樹枝覆蓋土壤水分下滲約300 cm,薄膜覆蓋土壤水分下滲約450 cm。生草覆蓋、裸地、碎樹枝覆蓋和薄膜覆蓋處理下?lián)p失的土壤水分總和依次為68.42 mm、51.53 mm、47.88 mm和3.29 mm。薄膜覆蓋下土壤水分損失幾乎為零,其次為碎樹枝覆蓋、裸地和生草覆蓋。綜上所述,試驗所涉及的幾種典型覆蓋措施對土壤水分有不同的影響,其中薄膜覆蓋具有較強(qiáng)的增加林地土壤水分的作用,也就是說具有較好的土壤水分修復(fù)能力。同時,我們修復(fù)林地土壤干化土壤需要重視非生育期(冬季)的保墑覆蓋措施,因為冬季是林地土壤水分損失最為嚴(yán)重的時期,這點在我們生產(chǎn)實踐中還缺乏足夠的重視。
[Abstract]:In the loess hilly area, the soil dryness exists generally in the artificial forestland, and with the increase of the tree age, the drying phenomenon is increasing year by year. In order to explore the restoration ability of soil moisture under the typical cover measures of the semi-arid area, this paper aims at restoring the soil moisture of the forestland and preventing and controlling the permanent soil dry layer of the woodland soil. The method of large soil column and field mulching in the field was used to monitor the change of soil moisture during the growth period and non fertility period by combining the method of location monitoring and field sampling. The natural restoration ability of the soil under typical mulching of the mountain forest soil was explained. The following results were obtained: 1) the large soil column test was observed in the field of date tree growth. It was proved that the dry soil moisture showed an increasing trend month by month under the influence of rainfall, but the increase of soil moisture under different coverage measures was different. By September, the film covered? Covered branches covered? Bare land? Grasses covered (Kentucky bluegrass). The water content of bare land was higher than that of raw grass. Soil water storage is beneficial to the restoration of soil moisture. The soil water storage increment of three types of plant growth without plant growth is a linear rise with time, and there is a nonlinear relationship between the increment of soil water storage and time. The vertical change of soil moisture under different coverage is different with the depth of soil layer. The coefficient of variation decreases gradually. Grass mulching (POA grasses) and bare land are below 200 cm, basically stable, the broken branches cover less than 240 cm, and the film cover is under 340 cm to reach the stable.2). The soil water content under several covering measures is lower than the result of soil column test. The soil moisture restoration depth after the rainy season is smaller, and the soil moisture restoration is deep in bare land and grass cover. At about 150 cm, the restoration depth of soil moisture by broken branches is 200 cm, and the maximum restoration depth of soil moisture by film mulching is more than 260 cm.3. It is found that winter is the most critical period of soil moisture loss in one year through the observation of soil moisture in the non fertility period by large soil column test. The soil moisture in bare land is 0-230 cm range. Reduced from 16.88% to 10.42%; soil moisture was reduced from 14.67% to 11.35% in the range of 0-220 cm, and soil moisture in the 0-150cm range decreased from 18.77% to 14.61%, and the soil moisture in the cover 0-300 cm range was reduced from 20.51% to 18.02%, and the depth of soil moisture loss was 230, 220 cm, 150 cm and 300 cm., respectively. Soil moisture under ground and grass covered soil has almost no infiltration, while the broken branches and thin film covered soil moisture decreased at the same time, and there were obvious infiltration. The broken branches covered soil moisture under 300 cm, and the film covered soil moisture about 450 cm. and covered with grass, bare land, shredded branches and film cover treatment. The loss of soil moisture in turn is 68.42 mm, 51.53 mm, 47.88 mm and 3.29 mm. thin film covered soil moisture loss almost zero, followed by broken branches covering, bare land and grass cover. In summary, several typical cover measures involved in the experiment have different effects on soil moisture, in which film mulching has a strong increase of forest land. The effect of soil moisture means a good ability to repair soil moisture. At the same time, we need to pay more attention to the soil moisture conservation measures in the non fertility period (winter), because winter is the most serious time of the loss of soil moisture in the woodland, which is still lack of enough attention in our production practice.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S152.7

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