新疆草地蒸散与水分利用效率的时空特征

doi:10.17521/cjpe.2016.0142

摘要/Abstract

摘要：

新疆地处中国西北干旱区, 草地分布广泛, 具有重要的经济和生态价值, 其蒸散(ET)与水分利用效率(WUE)的研究还比较薄弱, 尤其是草地WUE的研究还较为缺乏。该研究基于Biome-BGC模型对气候变化背景下1979-2012年新疆不同区域、不同草地类型的ET与WUE的时空特征进行了系统模拟与分析。结果表明: 1979-2012年新疆草地年平均蒸散量为245.7 mm, 其年际变化趋势与降水变化趋势大体一致, 蒸散量总体低于降水量; 蒸散量高值区主要分布在天山、阿尔泰山、阿尔金山以及昆仑山北坡中低山带, 低值区主要分布在昆仑山高山区和平原荒漠区; 1979-2012年南疆草地年平均蒸散量为183.2 mm, 天山区域草地年平均蒸散量为357.9 mm, 北疆草地为221.3 mm, 冬季北疆草地蒸散量略大于天山区域草地; 新疆6类草地年平均蒸散量从大到小依次为中山草甸、沼泽草甸、典型草原、荒漠草原、高山草甸、盐生草甸, 这6类草地均是夏季蒸散量最高, 冬季最低, 春季略高于秋季。新疆草地WUE较高的区域主要集中在天山和阿尔泰山区域, WUE较低的区域主要集中在昆仑山高山区域及部分平原区域; 新疆草地全年WUE平均值为0.56 g·kg^-1, 其中春、夏、秋季分别为0.43 g·kg^-1、0.60 g·kg^-1和0.48 g·kg^-1; 1979-2012年WUE具有显著的区域差异: 北疆平均为0.73 g·kg^-1, 南疆为0.26 g·kg^-1, 天山区域为0.69 g·kg^-1; 不同草地WUE差异也较为显著, 由高到低依次为中山草甸、典型草原、沼泽草甸、盐生草甸、高山草甸、荒漠草原。

关键词: 蒸散, 水分利用效率, 气候变化, Biome-BGC, 干旱区

Abstract:

Aims Xinjiang is located in the hinterland of the Eurasian arid areas, with grasslands widely distributed. Grasslands in Xinjiang provide significant economic and ecological benefits. However, research on evapotranspiration (ET) and water use efficiency (WUE) of the grasslands is still relatively weak. This study aimed to explore the spatio-temporal characteristics on ET and WUE in the grasslands of Xinjiang in the context of climate change.Methods The Biome-BGC model was used to determine the spatio-temporal characteristics of ET and WUE of the grasslands over the period 1979-2012 across different seasons, areas and grassland types in Xinjiang.Important findings The average annual ET in the grasslands of Xinjiang was estimated at 245.7 mm, with interannual variations generally consistent with that of precipitation. Overall, the value of ET was lower than that of precipitation. The higher values of ET mainly distributed in the Tianshan Mountains, Altai Mountains, Altun Mountains and the low mountain areas on the northern slope of Kunlun Mountains. The lower values of ET mainly distributed in the highland areas of Kunlun Mountains and the desert plains. Over the period 1979-2012, average annual ET was 183.2 mm in the grasslands of southern Xinjiang, 357.9 mm in the grasslands of the Tianshan Mountains, and 221.3 mm in grasslands of northern Xinjiang. In winter, ET in grasslands of northern Xinjiang was slightly higher than that of Tianshan Mountains. Average annual ET ranked among grassland types as: mid-mountain meadow > swamp meadow > typical grassland > desert grassland > alpine meadow > saline meadow. The highest ET value occurred in summer, and the lowest ET value occurred in winter, with ET in spring being slightly higher than that in autumn. The higher WUE values mainly distributed in the areas of Tianshan Mountains and Altai Mountains. The lower WUE values mainly distributed in the highland areas of Kunlun Mountains and part of the desert plains. The average annual WUE in the grasslands of Xinjiang was 0.56 g·kg^-1, with the seasonal values of 0.43 g·kg^-1 in spring, 0.60 g·kg^-1 in summer, and 0.48 g·kg^-1 in autumn, respectively. Over the period 1979-2012, the values of WUE displayed significant regional differences: the average values were 0.73 g·kg^-1 in northern Xinjiang, 0.26 g·kg^-1 in southern Xinjiang, and 0.69 g·kg^-1 in Tianshan Mountains. There were also significant differences in WUE among grassland types. The values of WUE ranked in the order of mid-mountain meadow > typical grassland > swamp meadow > saline meadow > alpine meadow > desert grassland.

Key words: evapotranspiration, water use efficiency, climate change, Biome-BGC, arid area

黄小涛, 罗格平. 新疆草地蒸散与水分利用效率的时空特征. 植物生态学报, 2017, 41(5): 506-518. DOI: 10.17521/cjpe.2016.0142

Xiao-Tao HUANG, Ge-Ping LUO. Spatio-temporal characteristics of evapotranspiration and water use efficiency in grasslands of Xinjiang. Chinese Journal of Plant Ecology, 2017, 41(5): 506-518. DOI: 10.17521/cjpe.2016.0142

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2016.0142

https://www.plant-ecology.com/CN/Y2017/V41/I5/506

图/表 12

图1 研究区略图。A, 地形与分区。B, 草地类型。C, 草地年降水量。D, 草地年平均气温。

Fig. 1 Sketch map of study areas. A, Topography and regional classification. B, Grassland types. C, Mean annual precipitation in grasslands. D, Average annual temperature in grasslands.

表1 根据前人研究校正的Biome-BGC模型参数

Table 1 Parameters of the Biome-BGC model calibrated based on previous studies

参数 Parameter	盐生草甸、平原荒漠草原和平原沼泽草甸 Saline meadow, plain desert grassland and plain swamp meadow	典型草原和低山沼泽草甸 Typical grassland and low mountain swamp meadow	中山草甸和中山沼泽草甸 Mid-mountain meadow and mid-mountain swamp meadow	高山草甸、高山荒漠草原和高山沼泽草甸 Alpine meadow, alpine desert grassland and alpine swamp meadow
一年中开始生长的年序日 Day of the year to start new growth	80	85	100	112
一年中结束生长的年序日 Day of the year to end litter fall	310	317	300	270
新根与新叶中碳分配比例 Ratio of C allocation to new fine roots over new leaves	4.0	3.0	2.0	2.5
冠层平均比叶面积 Canopy-average specific leaf area (m²·kg^-1)	12.5	12.0	30.0	25.0

图2 Biome-BGC模型模拟日尺度蒸散(ET)验证。A, 乌鲁木齐县典型草原验证点。B, 阿克苏高山草甸验证点。RMSE, 均方根误差。

Fig. 2 Validation of simulated daily evapotranspiration (ET) by Biome-BGC model. A, Validation site in typical grassland of Ürümqi County. B, Validation site in alpine meadow of Aksu. RMSE, root mean squared error.

图3 Biome-BGC模型模拟地上净初级生产力(ANPP)和净初级生产力(NPP)验证。A, ANPP验证。B, NPP验证。RMSE, 均方根误差。

Fig. 3 Validation of simulated aboveground net primary productivity (ANPP) and net primary productivity (NPP) by Biome-BGC model. A, ANPP validation. B, NPP validation. RMSE, root mean squared error.

图4 1979-2012年研究区草地蒸散(ET)时空分布。A, 年平均ET空间分布。B, 不同季节ET年际变化。

Fig. 4 Spatio-temporal distribution of evapotranspiration (ET) in grasslands of study area during 1979-2012. A, Spatial distribution of annual average ET. B, Interannual variability of ET across different seasons.

图5 1979-2012年新疆草地蒸散(ET)、降水和气温的变化。A, 全年。B, 春季。C, 夏季。D, 秋季。E, 冬季。

Fig. 5 Changes in evapotranspiration (ET), precipitation and air temperature in grasslands of Xinjiang during 1979-2012. A, Annual. B, Spring. C, Summer. D, Autumn. E, Winter.

表3 新疆草地蒸散(ET)分区统计(单位: mm)

Table 3 Regional statistics of evapotranspiration (ET) in grasslands of Xinjiang (unit: mm)

	春 Spring	夏 Summer	秋 Autumn	冬 Winter	年 Year
南疆 South Xinjiang	35.7	107.5	33.5	6.5	183.2
北疆 North Xinjiang	44.9	121.2	39.7	15.5	221.3
天山 Tianshan Mountains	67.0	213.3	63.0	14.6	357.9

表4 新疆草地蒸散(ET)分类统计(单位: mm)

Table 4 The statistics of evapotranspiration (ET) for different grassland types in Xinjiang (unit: mm)

类型 Type	春 Spring	夏 Summer	秋 Autumn	冬 Winter	年 Year
高山草甸 Alpine meadow	47.2	134.8	40.2	7.5	229.7
中山草甸 Mid-mountain meadow	72.4	231.9	64.8	18.5	387.7
典型草原 Typical grassland	64.7	202.3	59.6	17.3	343.9
荒漠草原 Desert grassland	45.1	136.1	43.0	11.9	236.2
盐生草甸 Saline meadow	32.3	87.0	28.8	6.5	154.7
沼泽草甸 Swamp meadow	68.3	212.3	60.1	17.7	358.3

图6 1979-2012年研究区草地水分利用效率(WUE)的时空分布。A, 年平均WUE空间分布。B, 不同季节WUE年际变化。

Fig. 6 Spatio-temporal distribution of water use efficiency (WUE) in grasslands of study area during 1979-2012. A, Spatial distribution of annual average WUE. B, Interannual variability of WUE across different seasons.

表5 新疆草地水分利用效率(WUE)分区统计(单位: g·kg-1)

Table 5 Regional statistics of water use efficiency (WUE) in grasslands of Xinjiang (unit: g·kg-1)

	春 Spring	夏 Summer	秋 Autumn	年 Year
南疆 South Xinjiang	0.24	0.29	0.24	0.26
北疆 North Xinjiang	0.67	0.92	0.66	0.73
天山 Tianshan Mountains	0.56	0.82	0.65	0.69

表6 新疆草地水分利用效率(WUE)分类统计(单位: g·kg-1)

Table 6 The statistics of water use efficiency (WUE) for different grassland types in Xinjiang (unit: g·kg-1)

类型 Type	春 Spring	夏 Summer	秋 Autumn	年 Year
高山草甸 Alpine meadow	0.23	0.44	0.38	0.37
中山草甸 Mid-mountain meadow	0.62	1.05	0.81	0.86
典型草原 Typical grassland	0.70	1.01	0.76	0.84
荒漠草原 Desert grassland	0.36	0.41	0.31	0.34
盐生草甸 Saline meadow	0.50	0.63	0.47	0.52
沼泽草甸 Swamp meadow	0.56	0.92	0.73	0.77

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