不同土地利用方式和施肥对高寒草甸土壤有机碳储量的影响

发布时间：2018-02-25 04:31

本文关键词： 土地利用方式施肥植物碳储量土壤有机碳储量微生物碳累积碳矿化量碳氮比氮磷比高寒草甸　出处：《兰州大学》2017年硕士论文　论文类型：学位论文

【摘要】：土壤是陆地生态系统最大的有机碳库。不同的土地利用方式和施肥通过改变土壤有机碳输入与输出的平衡进而影响土壤有机碳储量,而土壤有机碳储量的微小变化将会对全球气候变化产生重要影响。本文研究不同土地利用方式和施肥如何改变青藏高原高寒草甸植物与土壤理化性质进而对土壤有机碳储量产生影响。目的是为选择合适的土地利用方式和施肥措施提高植物生产力和维持土壤碳库功能提供理论依据。本文选择研究区典型的土地利用方式(围栏封育天然草甸、中度放牧草甸、农耕地和弃耕地)和施肥措施(对照和不同剂量的单施氮肥、单施磷肥和氮磷合施),测定了不同土地利用方式和施肥处理下的植物生物量及碳氮磷、表层土壤碳组分和氮磷以及理化性质。结果如下:1)农耕显著降低土壤容重和p H值;单施氮肥增加土壤容重,降低p H值。2)四种土地利用方式下,植物地上碳储量占总的有机碳储量的0.7%-1.7%,且在围栏封育天然草甸占比最大,根系碳储量占比是2.5%-4.3%,且最高占比在中度放牧草甸;不同施肥处理下,植物地上碳储量占总的有机碳储量的0.57%-2.35%,而根系碳储量占比是2.01%-3.89%,最大占比均是在中剂量单施氮肥。3)中度放牧显著增加土壤微生物量碳,而农耕与弃耕显著降低土壤微生物量碳;中度放牧、农耕和弃耕均显著降低土壤累积碳矿化量;施肥降低土壤微生物量碳和累积碳矿化量。4)农耕显著降低土壤有机碳储量;与不施肥的对照相比,中、高剂量单施氮肥和中剂量单施磷肥处理下,土壤有机碳储量分别增加3.92%、2.32%和0.45%,而其他施肥处理下,土壤有机碳储量降低0.66%-6.64%。5)弃耕降低植物地上碳氮比,增加根系碳氮比、植物和土壤氮磷比;低剂量单施氮肥与高剂量氮磷合施显著降低根系和土壤碳氮比;单施氮肥显著增加植物氮磷比,而施磷肥则降低植物氮磷比;施肥降低土壤氮磷比。总之,在青藏高原高寒草甸,不同土地利用方式和施肥改变植物的生产力、碳浓度、碳氮比和氮磷比,以及土壤理化性质和微生物特性,进而导致了中度放牧、弃耕、中剂量与高剂量单施氮肥下具有较高的土壤有机碳储量,而农耕和施磷肥则降低土壤有机碳积累。这些结果可以为选择合适的土地利用方式和施肥措施提高植物生产力、维持土壤碳库功能提供理论依据。
[Abstract]:Soil is the largest organic carbon pool in terrestrial ecosystems. Different land use patterns and fertilization affect soil organic carbon reserves by changing the balance of soil organic carbon input and output. The small change of soil organic carbon reserves will have an important impact on global climate change. This paper studies how different land use patterns and fertilization change the physical and chemical properties of alpine meadow plants and soil on the Qinghai-Xizang Plateau. The purpose of this paper is to provide a theoretical basis for selecting suitable land use methods and fertilization measures to improve plant productivity and maintain soil carbon pool function. Fencing natural meadows, Medium grazing meadow, agricultural land and abandoned farmland) and fertilization measures (control and different doses of single nitrogen fertilizer, single application of phosphorus fertilizer and combined application of nitrogen and phosphorus) were used to measure plant biomass and carbon, nitrogen and phosphorus under different land use patterns and fertilization treatments. The results were as follows: (1) farming significantly reduced soil bulk density and pH value, and applied nitrogen fertilizer alone increased soil bulk density and decreased pH value. Plant aboveground carbon storage accounted for 0.7-1.7% of total organic carbon storage, and the ratio of root carbon storage to natural meadow was the largest in fencing natural meadow, root carbon storage ratio was 2.5-4.3cm, and the highest proportion was in moderate grazing meadow; under different fertilization treatments, the ratio of root carbon storage was 2.5 to 4.3, and the highest percentage was in moderate grazing meadow. Plant aboveground carbon storage accounted for 0.57-2.35% of total organic carbon storage, while root root carbon storage ratio was 2.01-3.89, the largest proportion was moderate grazing with medium dose nitrogen fertilizer. 3) soil microbial biomass carbon was significantly increased by moderate grazing, while soil microbial biomass carbon was significantly reduced by farming and abandonment. Moderate grazing, farming and abandonment significantly reduced soil accumulated carbon mineralization; fertilization decreased soil microbial biomass carbon and cumulative carbon mineralization .4) farming significantly reduced soil organic carbon reserves. Soil organic carbon storage increased by 3.92% and 0.45%, respectively, under high dose nitrogen fertilizer and medium dose single phosphate fertilizer treatment, while under other fertilization treatments, soil organic carbon storage decreased by 0.66-6.64.5) abandoned tillage decreased plant aboveground carbon / nitrogen ratio and increased root carbon nitrogen ratio. The ratio of plant to soil nitrogen and phosphorus; the combination of low dose nitrogen fertilizer and high dose nitrogen and phosphorus fertilizer significantly decreased root and soil carbon to nitrogen ratio; single nitrogen fertilizer application significantly increased plant nitrogen and phosphorus ratio, while phosphorus fertilizer decreased plant nitrogen and phosphorus ratio; fertilization reduced soil nitrogen and phosphorus ratio. In alpine meadow of Qinghai-Xizang Plateau, different land use patterns and fertilization changed plant productivity, carbon concentration, C / N ratio and N / P ratio, as well as soil physical and chemical properties and microbial characteristics, which resulted in moderate grazing and abandonment of tillage. Medium and high doses of N fertilizer had higher soil organic carbon storage, while farming and application of phosphorus fertilizer could reduce soil organic carbon accumulation. These results could improve plant productivity by selecting appropriate land use methods and fertilization measures. The maintenance of soil carbon pool function provides theoretical basis.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812.2

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