陕北黄土丘陵区土地利用方式对土壤水碳垂直分布的影响

发布时间：2018-05-07 05:30

  本文选题：黄土高原 + 土地利用方式　； 参考：《西北农林科技大学》2017年硕士论文

【摘要】：黄土高原占世界黄土总面积的70%,该地区拥有独特的气候特征,植被资源和土壤特性,是我国生态文明建设的重点区域。自国家实施退耕还林的近20年来,黄土高原地区土地利用类型发生了重大变化,土地利用变化的同时也改变了土壤水文状况及土壤碳含量。因此近年来越来越多的研究集中在不同土地利用下土壤水分及碳含量的研究,但这些研究大多集中在表层土壤中,对深层土壤特别是10 m以下的土壤水分和碳分布状况的研究较少。基于此,本研究以黄土高原典型丘陵区的高西沟为主要研究区域,通过野外采样和室内分析相结合,研究了该地区侧柏林、油松林以及苹果园等不同不同土地利用方式下20 m深土壤剖面的水分、有机碳和无机碳分布特征,并结合土壤容重、pH、机械组成和根系分布等因素,系统的阐述了土壤水分和土壤碳在不同土地利用方式下的变化特征,得出以下主要结论:(1)4种类型的机械组成差别较大,其中表层土壤(0~2 m)的砂粒含量大小表现为农田苹果园油松林≈侧柏林,且深层土壤砂粒含量无固定变化趋势;粉粒含量在表层土壤表现为油松≈侧柏农田≈苹果,随着深度的增加农地粉粒含量逐渐增大,要远大于其他三种林地;在整个剖面农田粘粒含量一直处于较低值,其他三种林地粘粒含量变化较小,其值表现为侧柏苹果油松农田。4种类型的土壤容重均随土层深度的增加呈增大趋势,农田变化趋势较大,表层土壤容重较其他三种林地低,随着深度的增加容重逐渐增大,深层平均土壤容重要大于其他三种林地。土壤pH无明显的变化规律,并且农田和林地无明显差异。(2)对农田和侧柏林、油松林和苹果园进行土壤水分特征分析发现,在20 m土层范围内土壤平均含水率为农田苹果园≈油松林≈侧柏林,其值分别为11.30%、6.66%、6.48%和5.92%。农田土壤含水率呈先减小后增大的趋势,随着深度的增加变化趋势并不明显,三种林地在表层含水量极速降低,在1~10 m深处于整个剖面的较低水平,10 m之后土壤含水率随着深度的增加逐渐增大,但其变化趋势并不明显,三种林地之间也无较显著差别。(3)本研究分析了不同土地利用方式下SOC变化规律,得出SOC含量均随深度的增加逐渐降低,表层土壤SOC变化较大,随着深度的增加变化逐渐减小;林地SOC的含量要远高于农田,林地整个20 m剖面的SOC储量约为农地的1.74倍。SIC含量的变化趋势与有机碳相反,即随土层深度的增加SIC呈上升趋势,但变化较缓慢,林地SIC含量与农田差异较小,但总体表现为林地农田;整个20 m深剖面的农地平均SIC含量为11.24 g·kg-1,约为林地(12.98 g·kg-1)SIC含量的86.6%。
[Abstract]:Loess Plateau accounts for 70% of the total loess area in the world. It has unique climatic characteristics, vegetation resources and soil characteristics, which is the key area of ecological civilization construction in China. In the past 20 years, the types of land use in the Loess Plateau have changed greatly, and the change of land use has also changed the soil hydrology and soil carbon content. Therefore, in recent years, more and more studies have focused on soil moisture and carbon content under different land use, but most of these studies are concentrated in the surface soil. The distribution of soil moisture and carbon in deep soil, especially under 10 m, was less studied. Based on this, this study took the high west gully of the typical hilly area of the Loess Plateau as the main research area, and studied the Platycladus orientalis forest in this area through the combination of field sampling and indoor analysis. The distribution characteristics of soil moisture, organic carbon and inorganic carbon in 20m deep soil profile under different land use patterns, such as Pinus tabulaeformis forest and apple orchard, combined with soil bulk density pH, mechanical composition and root distribution, etc. The variation characteristics of soil moisture and soil carbon under different land use patterns are systematically expounded. The following main conclusions are drawn that there are great differences in mechanical composition of four types of soil moisture and soil carbon. Among them, the sand content of surface soil was about Pinus tabulaeformis forest, and the sand content of deep soil had no fixed change trend, and the silt content in surface soil was that Pinus tabulaeformis 鈮，

本文编号：1855594