华北土石山区森林土壤大孔隙对土壤理化性质及根系的响应
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摘要
土壤大孔隙是土壤水分、空气、化学物质及污染物优先运移的主要通道,对其形成机制的研究至关重要。以往对大孔隙的量化局限于传统方法,大孔隙三维形态特征的量化分析及其影响因素是目前大孔隙的研究重点。利用CT扫描及图像处理分析技术量化大孔隙三维形态特征参数,同时测定土壤基本理化性质及根长密度,分析土壤大孔隙三维特征对土壤理化性质及根系的响应。结果表明:土壤密度及土壤砂粒含量与大孔隙特征参数不存在相关关系;土壤有机质含量、土壤根长密度与大孔隙体积密度、大孔隙表面积密度、大孔隙数量密度呈现显著正相关关系,与大孔隙平均迂曲度呈现显著负相关关系。林木根系与土壤有机质对土壤大孔隙三维特征产生积极影响,表现为根系及土壤有机质含量越多,则大孔隙含量也越多,并具有更差的弯曲度。在今后对山地森林抚育管理、土壤水分运动机理及地下水污染评估等研究过程中不能忽略根系及土壤有机质差异对土壤大孔隙的重要影响。
Soil macropore is the main channel for preferential transport of soil moisture, air,chemical substances and pollutants, so the studies on its formation mechanism are of great importance. In the past, the quantification of macropore was limited to the traditional methods. But nowadays, quantitative analysis of three-dimensional morphological characteristics of soil macropore and its influencing factors are the research focus. In this paper, CT scanning and image processing techniques were used to quantify the 3-D characteristic parameters of macropore, and the basic physical and chemical properties of soil and root length density were also determined. The correlations between soil physicochemical properties, soil roots and the 3-D characteristics of soil macropore were analyzed. The results showed that there was no correlation between soil density, soil sand contents and characteristic parameters of macropore; soil organic matter contents and root length density were significantly positively correlated with volume density, surface area density and number density of macropore, and significantly negatively correlated with mean tortuosity of macropore. Soil organic matter and roots had a positive impact on the 3-D characteristics of soil macropore, the more roots and organic matter contents, the more macropore contents, and the worse bending degree of macropore. In the future, the effects of root system and organic matter should not be neglected in the studies of forest tending and management, soil water movement mechanism and groundwater pollution assessment.
Soil macropore is the main channel for preferential transport of soil moisture, air,chemical substances and pollutants, so the studies on its formation mechanism are of great importance. In the past, the quantification of macropore was limited to the traditional methods. But nowadays, quantitative analysis of three-dimensional morphological characteristics of soil macropore and its influencing factors are the research focus. In this paper, CT scanning and image processing techniques were used to quantify the 3-D characteristic parameters of macropore, and the basic physical and chemical properties of soil and root length density were also determined. The correlations between soil physicochemical properties, soil roots and the 3-D characteristics of soil macropore were analyzed. The results showed that there was no correlation between soil density, soil sand contents and characteristic parameters of macropore; soil organic matter contents and root length density were significantly positively correlated with volume density, surface area density and number density of macropore, and significantly negatively correlated with mean tortuosity of macropore. Soil organic matter and roots had a positive impact on the 3-D characteristics of soil macropore, the more roots and organic matter contents, the more macropore contents, and the worse bending degree of macropore. In the future, the effects of root system and organic matter should not be neglected in the studies of forest tending and management, soil water movement mechanism and groundwater pollution assessment.
引文
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[2] Wang J,Qin Q,Bai Z.Characterizing the effects of opencast coal-mining and land reclamation on soil macropore distribution characteristics using 3 D CT scanning [J].Catena,2018,171:212-221.
[3] Jarvis N J.A review of non-equilibrium water flow and solute transport in soil macropores:Principles,controlling factors and consequences for water quality [J].European Journal of Soil Science,2007,58(3):523-546.
[4] Hao Z C,Feng J.Recent advances in water and solute movement in macro-porous soil [J].Irrigation and Drainage,2002,21(1):67-71.
[5] Grdens A I,imunek J,Jarvis N,et al.Twodimensional modelling of preferential water flow and pesticide transport from a tile-drained field [J].Journal of Hydrology,2006,329(3):647-660.
[6] Katuwal S,Norgaard T,Moldrup P,et al.Linking air and water transport in intact soils to macropore characteristics inferred from X-ray computed tomography [J].Geoderma,2015,237:9-20.
[7] Zhang J,Xu Z.Dye tracer infiltration technique to investigate macropore flow paths in Maka Mountain,Yunnan Province,China [J].Journal of Central South University,2016,23(8):2101-2109.
[8] Lamande M,Labouriau R,Holmstrup M,et al.Density of macropores as related to soil and earthworm community parameters in cultivated grasslands [J].Geoderma,2011,162:319-326.
[9] Fang H,Zhou H,Norton G J,et al.Interaction between contrasting rice genotypes and soil physical conditions induced by hydraulic stresses typical of alternate wetting and drying irrigation of soil [J].Plant and Soil,2018,430(1/2):233-243.
[10] Luo L,Lin H,Schmidt J.Quantitative relationships between soil macropore characteristics and preferential flow and transport [J].Soil Science Society of America Journal,2010,74(6):1929-1937.
[11] Luo L,Lin H,Li S.Quantification of 3-D soil macropore networks in different soil types and land uses using computed tomography [J].Journal of Hydrology,2010,393(1/2):53-64.
[12] Meng C,Niu J,Li X,et al.Quantifying soil macropore networks in different forest communities using industrial computed tomography in a mountainous area of North China [J].Journal of Soils and Sediments,2017,17(9):2357-2370.
[13] FAO,I I ASA,ISRIC,et al.Harmonized world soil database (version 1.1) [J].FAO,Rome Italy and IIASA,Laxenburg,Austraia,2009.
[14] 鲍士旦.土壤农化分析[J].3版.北京:中国农业出版社,2000.
[15] Yan H,Li K,Ding H,et al.Root morphological and proteomic responses to growth restriction in maize plants supplied with sufficient N [J].Journal of plant physiology,2011,168(10):1067-1075.
[16] 郑纪勇,邵明安,张兴昌.黄土区坡面表层土壤容重和饱和导水率空间变异特征[J].水土保持学报,2004,18(3):53-56.
[17] 刘目兴,吴丹,吴四平,等.三峡库区森林土壤大孔隙特征及对饱和导水率的影响[J].生态学报,2016,36(11):3189-3196.
[18] 曾强,徐则民,官琦,等.不同植被条件下斜坡土体大孔隙特征分析[J].岩石力学与工程学报,2016,35(增刊1):3343-3352.
[19] 张洪江,杜士才,程云,等.重庆四面山森林植物群落及其土壤保持与生态水文功能[M].北京:科学出版社,2010.
[20] 荐圣淇,赵传燕,彭焕华,等.利用染色示踪与图像处理术研究根系对土壤大孔隙的影响[J].兰州大学学报(自然科学版),2011,47(5):62-66.
[21] 王彬俨,程金花,张洪江,等.北京市昌平区农地土壤大孔隙形成的影响因素分析[J].西北农林科技大学学报(自然科学版),2013,41(5):81-86.
[22] 官琦,徐则民,田林.植被发育玄武岩斜坡土体大孔隙尺寸及其主要影响因素[J].应用生态学报,2013,24(10):2888-2896.
[23] Zhang Z B,Peng X,Zhou H,et al.Characterizing preferential flow in cracked paddy soils using computed tomography and breakthrough curve [J].Soil and Tillage Research,2015,146:53-65.
[24] Yang J L,Zhang G L.Water infiltration in urban soils and its effects on the quantity and quality of runoff [J].Journal of Soils and Sediments,2011,11(5):751-761.
[25] Saravanathiiban D S,Kutay M E,Khire M V.Effect of macropore tortuosity and morphology on preferential flow through saturated soil:A Lattice Boltzmann study [J].Computers and Geotechnics,2014,59:44-53.