【摘要】：土壤是陸地生態(tài)系統(tǒng)最大的碳庫。土壤有機碳儲量及其化學(xué)結(jié)構(gòu)是全球碳循環(huán)研究的核心內(nèi)容。本研究以內(nèi)蒙古小針茅荒漠草原為研究對象,利用野外控制試驗,研究了圍封、開墾和不同放牧梯度等草原利用方式對土壤理化因子、土壤酶活性、土壤有機碳儲量及其化學(xué)結(jié)構(gòu)的影響。主要研究結(jié)果如下：1.不同利用方式對小針茅荒漠草原土壤理化因子和土壤酶活性的影響不同。同一土層,開墾和放牧與圍封相比,小針茅荒漠草原土壤全氮和全磷含量、土壤脲酶、過氧化氫酶和堿性磷酸酶活性均呈不同程度的降低趨勢,而土壤pH值呈升高趨勢。隨著放牧強度的增加,土壤全氮和全磷含量、土壤脲酶、堿性磷酸酶、過氧化氫酶活性逐漸降低,土壤pH值逐漸升高。同一處理,隨著土層的加深,土壤全氮、全磷含量、土壤脲酶活性均表現(xiàn)為先增加后降低的趨勢,在30～40 cm達到最大值。2.不同利用方式對小針茅荒漠草原土壤有機碳儲量影響顯著,與圍封相比,開墾和放牧區(qū)土壤有機碳儲量減少,具體表現(xiàn)為圍封G0.50G0.94開墾G1.25,其中,G1.25和開墾區(qū)土壤有機碳儲量顯著(P0.05)低于圍封區(qū),隨著放牧強度的增加土壤有機碳儲量逐漸減少。同一土層,開墾和放牧與圍封相比,土壤有機碳含量、有機碳密度有降低的趨勢,隨著放牧強度的增加,土壤有機碳含量、有機碳密度也逐漸減小。同一處理,隨著土層的加深,土壤有機碳含量、有機碳密度先增加后降低,在30～40 cm土層達到最大值。3.不同利用方式對小針茅荒漠草原表層(0-20 cm)土壤活性有機碳含量影響顯著。與圍封相比,開墾和放牧降低了土壤水溶性有機碳、易氧化有機碳、微生物量碳含量,隨著放牧強度的增加,土壤活性有機碳含量均逐漸降低。不同利用方式對小針茅荒漠草原土壤活性有機碳占總有機碳的比例影響不同。放牧和開墾與圍封相比,表層土壤活性有機碳占總有機碳的比例降低。隨著放牧強度的增加,土壤水溶性有機碳比例、易氧化有機碳比例、微生物量碳比例均表現(xiàn)為逐漸降低的趨勢。土壤總有機碳、水溶性有機碳、易氧化有機碳、微生物量碳含量之間呈顯著或極顯著正相關(guān)關(guān)系,土壤有機碳及其活性組分之間相互連系、相互影響,可以通過活性有機碳的含量反應(yīng)土壤有機碳的變化,進而反應(yīng)土壤有機碳碳庫的變化。4.圍封、放牧和開墾對小針茅荒漠草原土壤有機碳結(jié)構(gòu)的影響主要在數(shù)量上,有機碳化學(xué)組分沒有發(fā)生變化,土壤有機碳以烷氧碳(34.86%～37.85%)為主,其次為烷基碳(26.05%～33.87%),再者為芳香碳(10.60%-17.69%)和羰基碳(14.57%～16.90%)。土壤腐殖化指數(shù)(烷基碳／烷氧碳)表現(xiàn)為圍封區(qū)開墾區(qū)G0.50G0.94G1.25,芳香性表現(xiàn)為G1.25G0.94開墾區(qū)G0.50圍封區(qū)。說明開墾和過度放牧使土壤有機碳穩(wěn)定性降低,而圍封休牧使土壤有機碳更趨穩(wěn)定,在土壤固碳方面有一定的意義。
[Abstract]:Soil is the largest carbon pool in terrestrial ecosystems. Soil organic carbon storage and its chemical structure are the core of the global carbon cycle research. In this study, using the desert steppe of Stipa nipponii in Inner Mongolia as the research object, the physical and chemical factors and the activity of soil enzyme were studied by means of enclosure, reclamation and different gradients of grazing grassland. Effects of soil organic carbon storage and its chemical structure. The main results are as follows: 1. The effects of different utilization methods on soil physical and chemical factors and soil enzyme activity in Stipa nipponii desert steppe were different. In the same soil layer, the contents of total nitrogen and total phosphorus, the activities of urease, catalase and alkaline phosphatase in the soil of the desert steppe of Stipa pinelliforme showed a decreasing trend, but the pH value of the soil increased. With the increase of grazing intensity, the contents of total nitrogen and phosphorus, the activities of soil urease, alkaline phosphatase and catalase decreased gradually, and the pH value of soil gradually increased. In the same treatment, with the deepening of soil layer, the contents of total nitrogen, total phosphorus and soil urease activity increased first and then decreased, and reached the maximum value at 30 ~ 40 cm. The effects of different utilization methods on soil organic carbon storage in Stipa nipponii desert steppe were significant. Compared with enclosure, the soil organic carbon storage in reclamation and herding areas decreased, which was manifested by enclosed G0.50G0.94 reclamation G1.25. Soil organic carbon storage in G1.25 and reclamation areas was significantly lower than that in enclosed areas (P0.05), and gradually decreased with the increase of grazing intensity. In the same soil layer, the soil organic carbon content and the organic carbon density decreased compared with the enclosed soil. With the increase of grazing intensity, the organic carbon content and the organic carbon density of the soil gradually decreased. In the same treatment, with the deepening of soil layer, the content of organic carbon and the density of organic carbon increased first and then decreased, and reached the maximum value at 30 ~ 40 cm. The soil active organic carbon content in the surface layer (0-20 cm) of Stipa pinifera desert steppe was significantly affected by different utilization patterns. Compared with enclosure, reclamation and grazing decreased soil water-soluble organic carbon, easily oxidized organic carbon, microbial biomass carbon content, with the increase of grazing intensity, the soil active organic carbon content decreased gradually. The proportion of soil active organic carbon to total organic carbon was different in the desert steppe of Stipa punctatus. Compared with enclosed soil, the proportion of active organic carbon in surface soil was lower than that in grazing and reclamation. With the increase of grazing intensity, the ratio of water-soluble organic carbon, easily oxidized organic carbon and microbial biomass carbon decreased gradually. Soil total organic carbon, water-soluble organic carbon, easily oxidized organic carbon, microbial biomass carbon content showed significant or extremely significant positive correlation, soil organic carbon and its active components were connected and affected each other. The change of soil organic carbon and the change of soil organic carbon pool can be reflected by the content of active organic carbon. 4. The effects of enclosure, grazing and reclamation on the soil organic carbon structure of Stipa pinellifordii desert steppe were mainly in quantity, but the organic carbon chemical components did not change, and alkoxy carbon (34.86% 37.85%) was the main organic carbon in soil. Alkyl carbon (26.05%), aromatic carbon (10.60-17.69%) and carbonyl carbon (14.57C 16.90%). The humification index of soil (alkyl carbon / alkoxy carbon) was G0.50G0.94G1.25 and the aromaticity was G0.50G0.94G1.25. The results showed that reclamation and overgrazing decreased the stability of soil organic carbon, but closed and closed grazing made soil organic carbon more stable, which had a certain significance in soil carbon sequestration.
【學(xué)位授予單位】：沈陽農(nóng)業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：S812.2

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