Water sources of Medicago sativa grown in different slope positions in Yanchi County of Ningxia

doi:10.3724/SP.J.1258.2014.00118

Abstract

Abstract: Aims Alfalfa (Medicago sativa) is considered as an elite forage with high economic and ecological values. In semi-arid areas of Northwest China, the low rainfall is far from satisfying water demand of alfalfa. The northern part of Yanchi County is adjacent to Mu Us desert and has a shallow groundwater table. In this area, groundwater could be the potential water sources for growing alfalfa. Our objective was to investigate the growth performance and potential water sources of alfalfa grown in four slope positions with different altitudes in the bottomland of northern Yanchi County. Method Stable ¹⁸O and D isotope compositions (δ ¹⁸O and δD) of different water sources and xylem water were analyzed in April, June, July and August 2013. IsoSource was used to calculate the probable contribution of different water sources to the total plant water uptake. Stomatal conductance, carbon isotope discrimination (Δ ¹³C) of whole plant, soil volumetric water content in the 0-300 cm soil profile were also determined. Important findings Slope position had a significant effect on water content in the 0-300 cm soil profile. Highest soil water content was found in the slope position of lowest altitude. The δ ¹⁸O-δD coordinates of soil water and plant stem xylem water were distributed on the right of Northwest China local meteoric water line (LMWL), indicating that oxygen and hydrogen isotopic compositions in the water sources of alfalfa were subjected to enrichment due to evaporation. The δ ¹⁸O values of soil water in the 0-450 cm profile increased with altitude. Soil water δ ¹⁸O values decreased with the depth of soil profile for a given slope position. Soil water δ ¹⁸O values in deep profile were similar to those in groundwater, implying that groundwater would move to the upper soil layer via soil capillary. Seasonal fluctuation was observed in soil water δ ¹⁸O in the 0-40 cm profile, while soil water δ ¹⁸O in profile below 270 cm was stable seasonally. Plant stem xylem water δ ¹⁸O value was significantly lower (p < 0.001) in the slope position 1 than in other three slope positions in April, July and August. Highest water utilization rate from deep soil profile (below 270 cm) was recorded for alfalfa grown in the slope position 1 in April, June and July. In August, alfalfa grown in the slope positions 1, 3 and 4 mainly used soil water in the 150-270 cm and 270-450 cm profiles and groundwater; highest dependence on soil water in the shallow profile (0-20 cm) was found in alfalfa grown in the slope position 2. Higher yield, whole plant Δ ¹³C value and stomatal conductance were observed in alfalfa grown in the slope position 1 than in other three slope positions. These results suggest that bottomland with lower altitude and shallow groundwater table should be adopted when planting alfalfa without irrigation in the semi-arid areas of Northwest China where average annual rainfall is around 280 mm. Thus, groundwater could contribute to better growth performance of alfalfa, leading to higher ecological and economic returns.

Key words: dry-land alfalfa, groundwater utilization, plant water source, stable oxygen and hydrogen isotopes

ZHU Lin,QI Ya-Shu,XU Xing. Water sources of Medicago sativa grown in different slope positions in Yanchi County of Ningxia[J]. Chin J Plant Ecol, 2014, 38(11): 1226-1240.

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URL: https://www.plant-ecology.com/EN/10.3724/SP.J.1258.2014.00118

https://www.plant-ecology.com/EN/Y2014/V38/I11/1226

Figures/Tables 12

References 43

1	An H, An Y ( 2011). Soil moisture dynamics and water balance of Salix psammophila shrubs in south edge of Mu Us Sandy Land. Chinese Journal of Applied Ecology, 22, 2247-2252. (in Chinese with English abstract)
	[ 安慧, 安钰 ( 2011). 毛乌素沙地南缘沙柳灌丛土壤水分及水量平衡. 应用生态学报, 22, 2247-2252.]
2	Bian JJ, Sun ZY, Zhou AG, Yu SW ( 2009). Advances in the D and ¹⁸O isotopes of water source of plants in arid areas . Geological Science and Technology Information, 28(4), 117-120. (in Chinese with English abstract)
	[ 边俊景, 孙自永, 周爱国, 余绍文 ( 2009). 干旱区植物水分来源的D, ¹⁸O同位素示踪研究进展 . 地质科技情报, 28(4), 117-120.]
3	Cheng DH, Wang WK, Hou GC, Yang HB, Li Y, Zhang EY ( 2012). Relationship between vegetation and groundwater in Mu Us desert. Journal of Jilin University (Earth Science Edition), 42, 184-189. (in Chinese with English abstract)
	[ 程东会, 王文科, 侯光才, 杨红斌, 李瑛, 张二勇 ( 2012). 毛乌素沙地植被与地下水关系. 吉林大学学报(地球科学版), 42, 184-189.]
4	Dawson TE ( 1993). Hydraulic lift and water use by plants: implications for water balance, performance and plant- plant interactions. Oecologia, 95, 565-574. DOI URL
5	Dawson TE, Ehleringer JR ( 1991). Streamside trees that do not use stream water. Nature, 350, 335-337. DOI URL
6	Ehdaie B, Hall AE, Farquhar GD, Nguyen HT, Waines JG ( 1991). Water-use efficiency and carbon isotope discrimination in wheat. Crop Science, 31, 1282-1288. DOI URL
7	Ehrlinger JR, Dawson TE ( 1992). Water uptake by plants: perspectives from stable isotope composition. Plant, Cell & Environment, 15, 1073-1082.
8	Ellsworth PZ, Williams DG ( 2007). Hydrogen isotope fractionation during water uptake by woody xerophytes. Plant and Soil, 291, 93-107. DOI URL
9	Farquhar GD, Ehleringer JR, Hubick KT ( 1989). Carbon isotope discrimination and photosynthesis. Annual Review of Plant Physiology and Plant Molecular Biology, 40, 503-537. DOI URL
10	Farquhar GD, Richards RA ( 1984). Isotopic composition of plant carbon correlates with water-use efficiency of wheat genotypes. Australian Journal of Plant Physiology, 11, 539-552.
11	Gazis C, Feng X ( 2004). A stable isotope study of soil water: evidence for mixing and preferential flow paths. Geoderma, 119, 97-111. DOI URL
12	Han JC, Liu YS, Luo LT ( 2012). Research on the core technology of remixing soil by soft rock and sand in the Maowusu sand land region. Chinese Land Science, 26(8), 87-94. (in Chinese with English abstract)
	[ 韩霁昌, 刘彦随, 罗林涛 ( 2012). 毛乌素沙地砒砂岩与沙快速复配成土核心技术研究. 中国土地科学, 26(8), 87-94.]
13	Huang JT, Yin LH, Dong JQ, Zhang J, Ma HY, Wang XY ( 2013). Response of Salix psammophila transpiration to precipitation at shallow groundwater area in Mu Us Desert. Journal of Northwest A & F University (Nature Science Edition), 41(11), 217-228. (in Chinese with English abstract)
	[ 黄金廷, 尹立河, 董佳秋, 张俊, 马洪云, 王晓勇 ( 2013). 毛乌素沙地地下水浅埋区沙柳蒸腾对降水的响应. 西北农林科技大学学报(自然科学版), 41(11), 217-228.]
14	Huang TM, Nie ZQ, Yuan LJ ( 2008). Temperature and geographical effects of hydrogen and oxygen isotopes in precipitation in West of China. Journal of Arid Land Resources and Environment, 22(8), 76-81. (in Chinese with English abstract)
	[ 黄天明, 聂中青, 袁利娟 ( 2008). 西部降水氢氧稳定同位素温度及地理效应. 干旱区资源与环境, 22(8), 76-81.]
15	Johnson RC, Basset LM ( 1991). Carbon isotope discrimination and water use efficiency in four cool-season grasses. Crop Science, 31, 157-162. DOI URL
16	Kramer PJ, Boyer JS (1995). Water Relations of Plants and Soils. Academic Press, New York, 1911-1917.
17	Li FM, Zhang ZW ( 1991). The study on water use of the alfalfa grassland and the Spipa bungeana grassland in Ningxia Yanchi. Acta Phytoecologica et Geobotanica Sinica, 15, 319-329. (in Chinese with English abstract)
	[ 李凤民, 张振万 ( 1991). 宁夏盐池长芒草草原和苜蓿人工草地水分利用研究. 植物生态学与地植物学学报, 15, 319-329.]
18	Li HB, Gao YY, Zhang JW, Liu CH, Yu YC, Xi LF ( 2006). Summary of researching on the dynamic regulation of water consumption of alfalfa. Agricultural Research in the Arid Areas, 24(6), 163-167. (in Chinese with English abstract)
	[ 李浩波, 高云英, 张景武, 刘春和, 余有成, 惠临风 ( 2006). 紫花苜蓿耗水规律及其用水效率研究. 干旱地区农业研究, 24(6), 163-167.]
19	Li YS ( 2002). Productivity dynamic of alfalfa and its effects on water eco-environment. Acta Pedologica Sinica, 39, 404-411. (in Chinese with English abstract)
	[ 李玉山 ( 2002). 苜蓿生产力动态及其水分生态环境效应. 土壤学报, 39, 404-411.]
20	Liu PS, Jia ZK, Li J, Wang JP, Li YP, Liu SX ( 2009). Moisture distribution characteristics and the time-space dynamics of the soil dry layer in alfalfa farm lands in arid regions of Southern Ningxia. Journal of Natural Resources, 24, 663-673. (in Chinese with English abstract) DOI URL
	[ 刘沛松, 贾志宽, 李军, 王俊鹏, 李永平, 刘世新 ( 2009). 宁南旱区紫苜蓿土壤干层水分特征及时空动态. 自然资源学报, 24, 663-673.] DOI URL
21	Liu ZM, Shan L, Deng XP ( 1993). Study on grass (grain crop rotation system in south ningxia hilly area) field water balance under different crop rotation system. Journal of Soil and Water Conservation, 7(4), 67-71.
22	Ma HY, Gong JD, Wang GX, Cheng GD ( 2005). Study on the characteristics of space-time change on soil moisture in arid region. Research of Soil and Water Conservation, 12(6), 231-234. (in Chinese with English abstract)
	[ 马海艳, 龚家栋, 王根绪, 程国栋 ( 2005). 干旱区不同荒漠植被土壤水分的时空变化特征分析. 水土保持研究, 12(6), 231-234.]
23	Meinzer FC, Clearwater MJ, Goldstein G ( 2001). Water transport in trees: current perspectives, new insights and some controversies. Environmental and Experimental Botany, 45, 239-262. DOI URL
24	Merah O, Monneveux P, Deléens E ( 2001). Relationships between flag leaf carbon isotope discrimination and several morpho-physiological traits in durum wheat genotypes under Mediterranean conditions. Environmental and Experimental Botany, 45, 63-71. DOI URL
25	Misra SC, Randive R, Rao VS, Sheshshayee MS, Serraj R, Monneveux P ( 2006). Relationship between carbon isotope discrimination, ash content and grain yield in wheat in the peninsular zone of India. Journal of Agronomy and Crop Science, 192, 352-362. DOI URL
26	Pan ZB, Yu F, Wang ZJ, Li SB, Zhang YR ( 2010). Effects of slope aspect and position on temporal and spatial variation of soil water content on alfalfa land in Loess hilly region of South Ningxia Hui Autonomous Region. Research of Soil and Water Conservation, 17(2), 141-144. (in Chinese with English abstract)
	[ 潘占兵, 余峰, 王占军, 李生宝, 张源润 ( 2010). 宁南黄土丘陵区坡向、坡位对苜蓿地土壤含水量时空变异的影响. 水土保持研究, 17(2), 141-144.]
27	Phillips DL, Gregg JW ( 2003). Source partitioning using stable isotopes: coping with too many sources. Oecologia, 136, 261-269. DOI URL
28	Picon-Cochard C, Nsourou-Obame A, Collet C, Guehl JM, Ferhi A ( 2001). Competition for water between walnut seedlings ( Juglans regia) and rye grass( Lolium perenne) assessed by carbon isotope discrimination and δ ¹⁸O enrichment. Tree Physiology, 21, 183-191. DOI URL PMID
29	Qu XN, Wang HR ( 2007). Climate change analysis in Yanchi County of Ningxia since recent 50 years. Ningxia Engineering Technology, 5, 321-322. (in Chinese with English abstract)
	[ 璩向宁, 王惠荣 ( 2007). 宁夏盐池县近50年气候变化特征分析. 宁夏工程技术, 5, 321-322.]
30	Shan L, Zhang SQ, Li WR ( 2008). Productivity and drought resistance of alfalfa. Journal of Agricultural Science and Technology, 10, 12-17. (in Chinese with English abstract)
	[ 山仑, 张岁岐, 李文娆 ( 2008). 论苜蓿的生产力与抗旱性. 中国农业科技导报, 10, 12-17.]
31	Sun HL, Lü ZY, Guo KZ, Xu B, Ma L ( 2008). Preliminary study on the effect of groundwater to artificial pasture SPAC system with shallow water table. Journal of Inner Mongolia Agricultural University (Natural Science Edition), 29(2), 148-153.
	[ 孙海龙, 吕志远, 郭克贞, 徐冰, 马丽 ( 2008). 浅埋条件下地下水对人工草地SPAC系统影响初探. 内蒙古农业大学学报(自然科学版), 29(2), 148-153.]
32	Thorburn PJ, Walker GR, Brunel JP ( 1993). Extraction of water from Eucalyptus trees for analysis of deuterium and oxygen-18: laboratory and field techniques. Plant, Cell & Environment, 16, 269-277.
33	Wang ZQ, Liu YB, Lu BJ ( 2003). A study on water restoration of dry soil layers in the semi-arid area of Loess Plateau. Acta Ecologica Sinica, 23, 1944-1950. (in Chinese with English abstract)
	[ 王志强, 刘宝元, 路炳军 ( 2003). 黄土高原半干旱区土壤干层水分恢复研究. 生态学报, 23, 1944-1950.]
34	Wei WL, Cheng JM, Gao Y, Liu W ( 2010). Effects of different site conditions on alfalfa field and path analysis in arid area of Northern Weihe River Basin. Bulletin of Soil and Water Conservation, 30(5), 73-78. (in Chinese with English abstract)
	[ 魏婉玲, 程积民, 高阳, 刘伟 ( 2010). 渭北旱塬区不同立地条件对紫花苜蓿产量的影响与通径分析. 水土保持通报, 30(5), 73-78.]
35	Xu X, Yuan HM, Li SH, Monneveux P ( 2007). Relationship between carbon isotope discrimination and grain yield in spring wheat under different water regimes and under saline conditions in the Ningxia Province (North-west China). Journal of Agronomy and Crop Science, 193, 422-434. DOI URL
36	Yang YD, Zhang JS, Cai GJ, Mo BR, Chai CS, Wang ZT ( 2008). Soil moisture dynamics of alfalfa pasture at different eco-sites in Gullied Loess Area (2008). Prataculturae Science, 25(10), 25-28. (in Chinese with English abstract)
	[ 杨永东, 张建生, 蔡国军, 莫保儒, 柴春山, 王子婷 ( 2008). 黄土丘陵区不同立地条件下紫花苜蓿地土壤水分动态变化. 草业科学, 25(10), 25-28.]
37	Yu L, Wang YR, Garnett T, Auricht G, Hang DL ( 2006). A study on physiological responses of varieties of Medicago sativa and their relationship with the drought resistance capacity under drought stress. Prataculturae Science, 15(3), 75-85. (in Chinese with English abstract)
	[ 余玲, 王彦荣, Garnett T, Auricht G, 韩德梁 ( 2006). 紫花苜蓿不同品种对干旱胁迫的生理响应. 草业学报, 15(3), 75-85.]
38	Yuan JJ, Yuan FG, Luo Y, Sun XM, Zhang N ( 2009). Estimation of groundwater use of winter wheat using H₂ ¹⁸O signatures: a preliminary study . Journal of Natural Resources, 24, 360-368. (in Chinese with English abstract) DOI URL
	[ 苑晶晶, 袁国富, 罗毅, 孙晓敏, 张娜 ( 2009). 利用δ ¹⁸O信息分析冬小麦对浅埋深地下水的利用 . 自然资源学报, 24, 360-368.] DOI URL
39	Zhang BY, Xu XX, Bai XH ( 2006). A study on soil moisture under different vegetations in loess hilly region. Agricultural Research in the Arid Areas, 24(2), 96-99. (in Chinese with English abstract)
	[ 张北赢, 徐学选, 白晓华 ( 2006). 黄土丘陵区不同土地利用方式下土壤水分分析. 干旱地区农业研究, 24(2), 96-99.]
40	Zhang XH, Wang HM, Xu BC, Li FM ( 2007). Soil water using and consume of three legumes on highland of Loess Plateau. Acta Botanica Boreal-Occidentalia Sinica, 27, 1428-1437. (in Chinese with English abstract)
	[ 张晓红, 王惠梅, 徐炳成, 李凤民 ( 2007). 黄土塬区3种豆科牧草对土壤水分的消耗利用研究. 西北植物学报, 27, 1428-1437.]
41	Zheng SX, Shangguan ZP ( 2007). Spatial patterns of foliar stable carbon isotope compositions of C₃ plant species in the Loess Plateau of China. Ecological Research, 22, 342-353. DOI URL
42	Zhou YD, Chen SP, Song WM, Lu Q, Lin GH ( 2011). Water- use strategies of two desert plants along a precipitation gradient in northwestern China. Chinese Journal of Plant Ecology, 35, 789-800. (in Chinese with English abstract) DOI URL
	[ 周雅聃, 陈世苹, 宋维民, 卢琦, 林光辉 ( 2011). 不同降水条件下两种荒漠植物的水分利用策略. 植物生态学报, 35, 789-800.] DOI URL
43	Zhu L, Xu X, Mao GL ( 2012). Water sources of shrubs grown in the northern Ningxia Plain of China characterized by shallow groundwater table. Chinese Journal of Plant Ecology, 36, 618-628. (in Chinese with English abstract) DOI URL
	[ 朱林, 许兴, 毛桂莲 ( 2012). 宁夏平原北部地下水埋深浅地区不同灌木的水分来源. 植物生态学报, 36, 618-628.] DOI URL

	海拔 Altitude (m)	地下水位 Groundwater table (m)	生境类型 Type of habitat	土层深度 Soil depth (cm)	土壤机械组成 Soil mechanical composition	0-300 cm土壤体积含水量 Soil volumetric water content (%)
坡1 Slope position 1	1 317	3.2-3.7	丘间低地 Lowland on the foothill	0-20	砂粒 Sand 60.5%, 粉粒 Silt 20.1%, 黏粒 Clay 19.4%	9.6-12.4
				20-300	砂粒 Sand 49.1%, 粉粒 Silt 22.4%, 黏粒 Clay 28.5%
				>300	砂粒 Sand 42.4%, 粉粒 Silt 26.4%, 黏粒 Clay 31.2%
坡2 Slope position 2	1 322	4.8-5.5	丘间低地 Lowland on the foothill	0-20	砂粒 Sand 71.7%, 粉粒 Silt 12.9%, 黏粒 Clay 15.4%	6.8-8.4
				20-300	石砾 Gravel 15.3%, 砂粒 Sand 46.2%, 粉粒 Silt 20.6%, 黏粒 Clay 17.9%
				>300	石砾 Gravel 9.6%, 砂粒 Sand 49.8%, 粉粒 Silt 18.5%, 黏粒 Clay 22.1%
坡3 Slope position 3	1 324	5.5-6.0	丘间低地 Lowland on the foothill	0-20	砂粒 Sand 77.5%, 粉粒 Silt 11.9%, 黏粒 Clay 10.6%	5.8-6.8
				20-300	石砾 Gravel 5.3%, 砂粒 Sand 61.1%, 粉粒 Silt 24.5%, 黏粒 Clay 9.1%
				>300	石砾 Gravel 3.1%, 砂粒 Sand 62.3%, 粉粒 Silt 21.5%, 黏粒 Clay 13.1%
坡4 Slope position 4	1 328	>6.0	缓坡丘陵梁地 Flat hilly highland	0-20	砂粒 Sand 67.5%, 粉粒 Silt 21.9%, 黏粒 Clay 10.6%	5.6-7.8
				20-300	砂粒 Sand 63.3%, 粉粒 Silt 25.5%, 黏粒 Clay 11.2%
				>300	砂粒 Sand 46.8%, 粉粒 Silt 38.5%, 黏粒 Clay 14.7%

	海拔 Altitude (m)	地下水位 Groundwater table (m)	生境类型 Type of habitat	土层深度 Soil depth (cm)	土壤机械组成 Soil mechanical composition	0-300 cm土壤体积含水量 Soil volumetric water content (%)
坡1 Slope position 1	1 317	3.2-3.7	丘间低地 Lowland on the foothill	0-20	砂粒 Sand 60.5%, 粉粒 Silt 20.1%, 黏粒 Clay 19.4%	9.6-12.4
				20-300	砂粒 Sand 49.1%, 粉粒 Silt 22.4%, 黏粒 Clay 28.5%
				>300	砂粒 Sand 42.4%, 粉粒 Silt 26.4%, 黏粒 Clay 31.2%
坡2 Slope position 2	1 322	4.8-5.5	丘间低地 Lowland on the foothill	0-20	砂粒 Sand 71.7%, 粉粒 Silt 12.9%, 黏粒 Clay 15.4%	6.8-8.4
				20-300	石砾 Gravel 15.3%, 砂粒 Sand 46.2%, 粉粒 Silt 20.6%, 黏粒 Clay 17.9%
				>300	石砾 Gravel 9.6%, 砂粒 Sand 49.8%, 粉粒 Silt 18.5%, 黏粒 Clay 22.1%
坡3 Slope position 3	1 324	5.5-6.0	丘间低地 Lowland on the foothill	0-20	砂粒 Sand 77.5%, 粉粒 Silt 11.9%, 黏粒 Clay 10.6%	5.8-6.8
				20-300	石砾 Gravel 5.3%, 砂粒 Sand 61.1%, 粉粒 Silt 24.5%, 黏粒 Clay 9.1%
				>300	石砾 Gravel 3.1%, 砂粒 Sand 62.3%, 粉粒 Silt 21.5%, 黏粒 Clay 13.1%
坡4 Slope position 4	1 328	>6.0	缓坡丘陵梁地 Flat hilly highland	0-20	砂粒 Sand 67.5%, 粉粒 Silt 21.9%, 黏粒 Clay 10.6%	5.6-7.8
				20-300	砂粒 Sand 63.3%, 粉粒 Silt 25.5%, 黏粒 Clay 11.2%
				>300	砂粒 Sand 46.8%, 粉粒 Silt 38.5%, 黏粒 Clay 14.7%

	采样时间 Sampling time	产量 Yield (kg·hm^-2)	株高 Plant height (m)	茎叶比 Ratio of stem to leaf
坡1 Slope position 1	6月2日 2 June	1 368.60 ± 89.24^aA	48.67 ± 1.53^aB	1.25 ± 0.33^aA
坡1 Slope position 1	8月19日19 August	1 933.85 ± 40.66^aA	63.33 ± 1.64^aA	1.35 ± 0.21^aA
坡2 Slope position 2	6月2日 2 June	806.20 ± 162.07^cA	44.67 ± 4.51^aB	1.08 ± 0.08^aA
坡2 Slope position 2	8月19日19 August	1 752.90 ± 66.61^aA	61.33 ± 2.51^aA	1.22 ± 0.30^aA
坡3 Slope position 3	6月2日 2 June	1 039.95 ± 122.26^bB	47.00 ± 3.61^aB	1.15 ± 0.19^aB
坡3 Slope position 3	8月19日19 August	1 885.80 ± 116.39^aA	63.00 ± 2.65^aA	1.40 ± 0.39^aA
坡4 Slope position 4	6月2日 2 June	928.85 ± 241.05^bcA	43.00 ± 5.29^aB	1.32 ± 0.15^aA
坡4 Slope position 4	8月19日19 August	1 401.25 ± 88.32^bA	57.00 ± 4.36^aA	1.59 ± 0.22^aA

	采样时间 Sampling time	产量 Yield (kg·hm^-2)	株高 Plant height (m)	茎叶比 Ratio of stem to leaf
坡1 Slope position 1	6月2日 2 June	1 368.60 ± 89.24^aA	48.67 ± 1.53^aB	1.25 ± 0.33^aA
坡1 Slope position 1	8月19日19 August	1 933.85 ± 40.66^aA	63.33 ± 1.64^aA	1.35 ± 0.21^aA
坡2 Slope position 2	6月2日 2 June	806.20 ± 162.07^cA	44.67 ± 4.51^aB	1.08 ± 0.08^aA
坡2 Slope position 2	8月19日19 August	1 752.90 ± 66.61^aA	61.33 ± 2.51^aA	1.22 ± 0.30^aA
坡3 Slope position 3	6月2日 2 June	1 039.95 ± 122.26^bB	47.00 ± 3.61^aB	1.15 ± 0.19^aB
坡3 Slope position 3	8月19日19 August	1 885.80 ± 116.39^aA	63.00 ± 2.65^aA	1.40 ± 0.39^aA
坡4 Slope position 4	6月2日 2 June	928.85 ± 241.05^bcA	43.00 ± 5.29^aB	1.32 ± 0.15^aA
坡4 Slope position 4	8月19日19 August	1 401.25 ± 88.32^bA	57.00 ± 4.36^aA	1.59 ± 0.22^aA

	水分来源 Water source		δ¹⁸O (‰)	坡位1 Slope position 1	δ¹⁸O (‰)	坡位2 Slope position 2	δ¹⁸O (‰)	坡位3 Slope position 3	δ¹⁸O (‰)	坡位4 Slope position 4
4月28日 28 April	土壤深度 Soil depth (cm)	0-20	-1.17	1.3 (0-5)	-2.22	37.4 (20-46)	-4.54	21.0 (0-46)	-3.65	49.1 (32-59)
		20-150	-7.93	8.6 (0-32)	-6.09	20.5 (0-70)	-6.15	25.4 (0-67)	-7.09	17.3 (0-68)
		150-270	-8.91	23.3 (0-85)	-7.43	15.9 (0-50)	-8.61	19.1 (0-67)	-8.56	11.6 (0-42)
		270-400	-9.51	51.6 (14-88)	-8.17	13.9 (0-45)	-9.74	15.3 (0-52)	-9.49	10.0 (0-35)
	地下水 Groundwater		-8.59	15.2 (0-54)	-8.59	12.2 (0-44)	-8.59	19.2 (0-64)	-8.59	12.0 (0-45)
6月2日 2-June	土壤深度 Soil depth (cm)	0-20	1.27	0.0 (0-2.9)	-3.19	0.6 (0-2)	-0.44	7.9 (0-17)	-5.24	9.1 (0-35)
		20-150	-8.07	1.3 (0-5)	-6.33	2.9 (1-6)	-4.35	14.7 (0-36)	-5.05	8.6 (0-33)
		150-270	-8.35	1.8 (0.4)	-8.87	5.3 (0-1.2)	-7.82	26.0 (0-83)	-7.58	25.0 (0-95)
		270-450	-8.96	94.8 (94-96)	-10.39	89.5 (85-93)	-8.19	25.5 (0-76)	-8.93	30.3 (0-65)
	地下水 Groundwater		-7.73	2.2 (0-4)	-7.73	1.7 (0-5)	-7.73	26.0 (0-83)	-7.73	27.0 (0-95)
7月19日 19-July	土壤深度 Soil depth (cm)	0-20	-6.04	2.9 (0-11)	-6.44	37.1 (0-84)	-6.63	93.0 (86-98)	-6.56	31.4 (0-82)
		20-150	-6.43	3.2 (0-12)	-6.29	40.8 (0-81)	-6.84	6.0 (0-14)	-5.92	36.2 (0-63)
		150-270	-8.78	11.0 (0-39)	-7.88	9.8 (0-32)	-8.10	0.6 (0-2)	-8.65	9.7 (0-35)
		270-450	-9.91	74.4 (59-87)	-9.21	5.3 (0-17)	-9.00	0.2 (0-1)	-8.10	12.3 (0-45)
	地下水 Groundwater		-8.47	8.4 (0-31)	-8.47	7.1 (0-23)	-8.47	0.2 (0-1)	-8.47	10.4 (0-39)
8月19日 19-August	土壤深度 Soil depth (cm)	0-20	-4.62	9.4 (0-31)	-2.82	40.5 (21.51)	-5.02	7.2 (0-28)	-2.47	5.1 (0-17)
		20-150	-7.27	17.4 (0-58)	-6.57	20.6 (0-75)	-6.61	10.7 (0-4)	-5.59	8.9 (0-32)
		150-270	-8.76	25.7 (0-91)	-8.12	14.5 (0-54)	-10.19	31.4 (0-69)	-8.10	22.8 (0-82)
		270-450	-10.33	22.0 (0-66)	-9.16	11.9 (0-46)	-8.50	22.8 (0-86)	-9.74	32.7 (0-80)
	地下水 Groundwater		-8.93	25.5 (0-90)	-8.93	12.5 (0-48)	-8.93	28 (0-92)	-8.93	30.5 (0-91)