Application of stable hydrogen isotope in study of water sources for Caragana microphylla bushland in Nei Mongol

doi:10.17521/cjpe.2015.0018

Abstract

Abstract: Aims

Caragana microphylla is a dominant shrub widely distributed in the grasslands of Nei Mongol. Its water utilization pattern has an important effect on local plant community composition. However, the water source for C. microphylla remains poorly quantified, which is vital in understanding the adaptation of this specie to arid environment. This study aims to investigate the dynamics of water use in C. microphylla and its response to soil water fluctuations resulting from precipitation pattern including summer rains and winter snow.

Methods

Seasonal variations of hydrogen stable isotope ratios (δD) in the xylem of C. microphylla and potential sources of water (summer rains, winter snow and soil water) were analyzed by LGR hydrogen stable isotope tracer method. The contribution of soil water to C. microphylla was calculated by IsoSource model and the contribution of rainfall to soil water was calculated by a two-source model.

Important findings

The xylem of C. microphylla (xylem) showed no seasonal differences in δD, whereas there were significant differences in the water source of plants between two contrasting hydrological environments. In habitats where rainfall was shielded off, C. microphylla mainly used the soil water at depth of 0-20 cm, which accounted for 73.30% ± 16.14% of the total water usage; whilst under natural conditions, water uptake by C. microphylla was more or less similar at the depths of 0-20 cm, 20-60 cm and 60-100 cm, accounting for 34.66% ± 7.83%, 32.44% ± 7.42%, 32.90% ± 4.14% of the total water usage, respectively. Competition for water between shrubs and grasses gave a possible explanation for different water utilization patterns of the plants. In addition, rainfall accounted for 42.65%-63.92% of the water sources for C. microphylla. Resultsin this study demonstrated that C. microphylla used both summer rains and winter snow, and dynamics of water use in C. microphylla reflects its adaptation to the water-limiting arid environment.

Key words: source of water use, deuterium isotope, Caragana microphylla, plant water use

ZHENG Xiao-Ran,ZHAO Guo-Qin,LI Xiao-Yan,LI Liu,WU Hua-Wu,ZHANG Si-Yi,ZHANG Zhi-Hua. Application of stable hydrogen isotope in study of water sources for Caragana microphylla bushland in Nei Mongol[J]. Chin J Plan Ecolo, 2015, 39(2): 184-196.

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Figures/Tables 11

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日期 Date (month-day)	降水量 Precipitation (mm)	降水强度 Precipitation intensity (mm·h^-1)	δD (‰)	月平均δD (平均值±标准偏差) Monthly average δD (‰) (mean ± SD)
6-9	6.6	0.2	-54.01	-48.20 ± 46.20
6-14	4.2	1.0	-5.89	-48.20 ± 46.20
7-8	15.6	1.2	-10.01	-42.80 ± 26.50
7-12	2.0	0.2	-38.47	-42.80 ± 26.50
8-8	6.2	3.6	-38.10	-50.84 ± 32.52

日期 Date (month-day)	降水量 Precipitation (mm)	降水强度 Precipitation intensity (mm·h^-1)	δD (‰)	月平均δD (平均值±标准偏差) Monthly average δD (‰) (mean ± SD)
6-9	6.6	0.2	-54.01	-48.20 ± 46.20
6-14	4.2	1.0	-5.89	-48.20 ± 46.20
7-8	15.6	1.2	-10.01	-42.80 ± 26.50
7-12	2.0	0.2	-38.47	-42.80 ± 26.50
8-8	6.2	3.6	-38.10	-50.84 ± 32.52

土壤深度 Soil depth (cm)	遮雨处理 Rain-exclusion treatment
土壤深度 Soil depth (cm)	日期 Date (month-day)
	4-20	6-11	6-15	7-8	7-14	8-9
0-5	-151.46 ± 17.39^a	-109.92 ± 30.98^a	-93.19 ± 35.33^a	-82.37 ± 6.97^a	-82.53 ± 18.76^a	-85.90 ± 4.45^a
5-10	-140.87 ± 27.79^a	-132.75 ± 34.01^a	-125.13 ± 22.85^a	-111.30 ± 1.96^ab	-96.05 ± 16.53^a	-97.08 ± 12.39^ab
10-20	-116.40 ± 5.83^abc	-144.64 ± 7.83^a	-137.39 ± 25.87^a	-124.57 ± 15.03^abc	-110.08 ± 36.13^a	-98.74 ± 16.74^ab
20-40	-89.31 ± 1.60^c	-163.35 ± 30.89^a	-148.37 ± 32.38^a	-152.23 ± 16.11^bc	-132.06 ± 9.74^b	-119.34 ± 22.01^abc
40-60	-92.37 ± 29.59^c	-154.73 ± 39.10^a	-143.87 ± 41.27^a	-155.80 ± 13.31^c	-142.22 ± 9.81^bc	-128.18 ± 17.92^bc
60-80	-101.28 ± 16.09^bc	-138.64 ± 42.40^a	-136.51 ± 37.99^a	-166.77 ± 21.93^c	-154.07 ± 0.23^c	-138.05 ± 12.59^c
80-100	-88.28 ± 13.99^c	-133.77 ± 29.10^a	-111.70 ± 14.02^a	-140.27 ± 18.60^b	-150.10 ± 10.17^c	-145.18 ± 0.42^c
总计 Total	-111.42 ± 28.30	-139.69 ± 28.91	-129.43 ± 30.40	-133.33 ± 30.28	-123.87 ± 29.85	-114.16 ± 23.93
土壤深度 Soil depth (cm)	自然状态 Natural condition
土壤深度 Soil depth (cm)	日期 Date (month-day)
	4-20	6-11	6-15	7-8	7-14	8-9
0-5	-161.74 ± 1.21^a	-80.65 ± 11.33^a	-46.96 ± 14.16^a	-44.55 ± 7.54^a	-39.07 ± 4.72^a	-73.09 ± 3.86^a
5-10	-145.11 ± 7.93^a	-116.48 ± 0.62^b	-82.27 ± 16.08^ab	-55.23 ± 22.23^a	-58.54 ± 18.07^ab	-83.77 ± 0.03^ab
10-20	-129.67 ± 41.18^a	-143.01 ± 12.45^c	-108.05 ± 23.09^b	-75.70 ± 19.69^ab	-80.23 ± 14.00^bc	-80.38 ± 18.94^a
20-40	-143.43 ± 33.96^a	-135.82 ± 8.17^c	-100.7 ± 20.72^b	-119.97 ± 19.88^c	-109.48 ± 9.59^c	-113.12 ± 21.33^b
40-60	-137.41 ± 38.22^a	-111.21 ± 3.98^b	-103.35 ± 32.47^b	-124.08 ± 16.14^c	-115.16 ± 30.70^c	-103.35 ± 16.54^ab
60-80	-106.92 ± 32.80^a	-103.74 ± 8.42^b	-93.11 ± 8.75^ab	-115.80 ± 10.20^bc	-100.41 ± 13.57^c	-91.16 ± 4.62^ab
80-100	-111.89 ± 21.70^a	-109.07 ± 5.05^b	-87.31 ± 17.86^ab	-129.67 ± 20.34^c	-92.01 ± 8.95^bc	-100.55 ± 0.26^ab
总计 Total	-135.54 ± 28.58	-114.28 ± 20.77	-88.82 ± 24.72	-95.00 ± 36.50	-84.59 ± 30.37	-92.24 ± 17.18

土壤深度 Soil depth (cm)	遮雨处理 Rain-exclusion treatment
土壤深度 Soil depth (cm)	日期 Date (month-day)
	4-20	6-11	6-15	7-8	7-14	8-9
0-5	-151.46 ± 17.39^a	-109.92 ± 30.98^a	-93.19 ± 35.33^a	-82.37 ± 6.97^a	-82.53 ± 18.76^a	-85.90 ± 4.45^a
5-10	-140.87 ± 27.79^a	-132.75 ± 34.01^a	-125.13 ± 22.85^a	-111.30 ± 1.96^ab	-96.05 ± 16.53^a	-97.08 ± 12.39^ab
10-20	-116.40 ± 5.83^abc	-144.64 ± 7.83^a	-137.39 ± 25.87^a	-124.57 ± 15.03^abc	-110.08 ± 36.13^a	-98.74 ± 16.74^ab
20-40	-89.31 ± 1.60^c	-163.35 ± 30.89^a	-148.37 ± 32.38^a	-152.23 ± 16.11^bc	-132.06 ± 9.74^b	-119.34 ± 22.01^abc
40-60	-92.37 ± 29.59^c	-154.73 ± 39.10^a	-143.87 ± 41.27^a	-155.80 ± 13.31^c	-142.22 ± 9.81^bc	-128.18 ± 17.92^bc
60-80	-101.28 ± 16.09^bc	-138.64 ± 42.40^a	-136.51 ± 37.99^a	-166.77 ± 21.93^c	-154.07 ± 0.23^c	-138.05 ± 12.59^c
80-100	-88.28 ± 13.99^c	-133.77 ± 29.10^a	-111.70 ± 14.02^a	-140.27 ± 18.60^b	-150.10 ± 10.17^c	-145.18 ± 0.42^c
总计 Total	-111.42 ± 28.30	-139.69 ± 28.91	-129.43 ± 30.40	-133.33 ± 30.28	-123.87 ± 29.85	-114.16 ± 23.93
土壤深度 Soil depth (cm)	自然状态 Natural condition
土壤深度 Soil depth (cm)	日期 Date (month-day)
	4-20	6-11	6-15	7-8	7-14	8-9
0-5	-161.74 ± 1.21^a	-80.65 ± 11.33^a	-46.96 ± 14.16^a	-44.55 ± 7.54^a	-39.07 ± 4.72^a	-73.09 ± 3.86^a
5-10	-145.11 ± 7.93^a	-116.48 ± 0.62^b	-82.27 ± 16.08^ab	-55.23 ± 22.23^a	-58.54 ± 18.07^ab	-83.77 ± 0.03^ab
10-20	-129.67 ± 41.18^a	-143.01 ± 12.45^c	-108.05 ± 23.09^b	-75.70 ± 19.69^ab	-80.23 ± 14.00^bc	-80.38 ± 18.94^a
20-40	-143.43 ± 33.96^a	-135.82 ± 8.17^c	-100.7 ± 20.72^b	-119.97 ± 19.88^c	-109.48 ± 9.59^c	-113.12 ± 21.33^b
40-60	-137.41 ± 38.22^a	-111.21 ± 3.98^b	-103.35 ± 32.47^b	-124.08 ± 16.14^c	-115.16 ± 30.70^c	-103.35 ± 16.54^ab
60-80	-106.92 ± 32.80^a	-103.74 ± 8.42^b	-93.11 ± 8.75^ab	-115.80 ± 10.20^bc	-100.41 ± 13.57^c	-91.16 ± 4.62^ab
80-100	-111.89 ± 21.70^a	-109.07 ± 5.05^b	-87.31 ± 17.86^ab	-129.67 ± 20.34^c	-92.01 ± 8.95^bc	-100.55 ± 0.26^ab
总计 Total	-135.54 ± 28.58	-114.28 ± 20.77	-88.82 ± 24.72	-95.00 ± 36.50	-84.59 ± 30.37	-92.24 ± 17.18

土壤深度 Soil depth (cm)	日期 Date (month-day)					平均值 Mean
土壤深度 Soil depth (cm)	6-11	6-15	7-8	7-14	8-9	平均值 Mean
0-5	76.22%	74.36%	77.87%	99.53%	72.65%	80.13%
5-10	44.25%	52.31%	71.02%	84.27%	64.31%	63.23%
10-20	20.57%	36.21%	57.90%	75.03%	66.96%	51.33%
20-40	26.99%	40.80%	29.53%	44.34%	41.37%	36.61%
40-60	48.95%	39.15%	26.90%	39.89%	39.87%	38.95%
60-80	55.62%	45.54%	32.21%	51.45%	58.53%	48.67%
80-100	50.86%	49.16%	23.32%	58.03%	51.19%	46.51%