青藏高原高寒草原土壤蒸发特征及其影响因素
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摘要
蒸发作为水量平衡和能量平衡的重要组成部分,在生物圈-水圈-大气圈中发挥着不可或缺的作用,其变化对于农业、生态水文具有重要的影响。青藏高原作为气候变暖的先兆区,冻土活动层厚度增加,改变大气和土壤的水热交换过程,为明确青藏高原冻土区蒸发在气候变暖大背景下的变化趋势,本研究选取典型冻土区色林错流域,于2017年8-9月、2018年7-9月利用小型蒸渗仪对植被覆盖度15%、30%和60%高寒草原土壤水分分布特征以及蒸发变化进行了定量研究,并探讨了其主要影响因素。结果表明:(1)植被覆盖度为15%,日均蒸发量最大,为2.25mm;植被覆盖度为60%的日均蒸发量最小,为1.88mm;在日蒸发过程上,12:00-16:00蒸发量最大,16:00-20:00蒸发量最小。(2)3种植被覆盖度条件下土壤水分最大值位于20-30cm层;最小值在土壤表层(0-10cm)。随植被覆盖度增加,土壤含水量增大,尤其是浅层土壤(20cm)表现的十分明显。(3)通过对地上生物量和蒸发量的相关性研究,生物量越大,蒸发量越低。(4)在高寒草原蒸发与气象要素关系研究中发现,蒸发主要受水汽压和净辐射的影响。
Evaporation, as an important component of water balance and energy balance, plays an indispensable role in the Biosphere-hydrosphere-atmosphere. In addition, the change of evaporation has an important influence on agriculture and ecological hydrology. The Tibet Plateau is a harbinger of climate change. The climate warming has led to the increase of permafrost activity layer thickness, changing the water and heat exchange processes between the atmosphere and the soil. In order to clarify the changing trend of evaporation under the background of climate warming in Tibet Plateau permafrost region, we chose Siling Co basin as the object. We quantified the evaporations from 15%, 30% and 60% vegetation coverages of Alpine prairies using the small lysimeters and discussed the main influencing factors. The results show that:(1) During the observation period, the daily average evaporation from 15% vegetation coverage was the highest with a value of 2.25 mm. In opposite, the daily average evaporation from 60% vegetation coverage was the lowest with a value of 1.88 mm. The maximum of evaporation occurred in 12:00-16:00 and the minimum occurred in 16:00-20:00 on the diurnal cycle.(2) The maximum soil moisture was distributed in the depth of 20-30 cm, while the minimum was distributed in the surface layer(0-10 cm) for three different vegetation coverage. Besides, the soil moisture content had a positive relationship with the vegetation coverage, especially in the surface layer(20 cm).(3) The evaporation had a negative relationship with the aboveground biomass.(4) According to the relationship between evaporation and meteorological elements, the result shows that evaporation was mainly affected by water vapor pressure and net radiation.
Evaporation, as an important component of water balance and energy balance, plays an indispensable role in the Biosphere-hydrosphere-atmosphere. In addition, the change of evaporation has an important influence on agriculture and ecological hydrology. The Tibet Plateau is a harbinger of climate change. The climate warming has led to the increase of permafrost activity layer thickness, changing the water and heat exchange processes between the atmosphere and the soil. In order to clarify the changing trend of evaporation under the background of climate warming in Tibet Plateau permafrost region, we chose Siling Co basin as the object. We quantified the evaporations from 15%, 30% and 60% vegetation coverages of Alpine prairies using the small lysimeters and discussed the main influencing factors. The results show that:(1) During the observation period, the daily average evaporation from 15% vegetation coverage was the highest with a value of 2.25 mm. In opposite, the daily average evaporation from 60% vegetation coverage was the lowest with a value of 1.88 mm. The maximum of evaporation occurred in 12:00-16:00 and the minimum occurred in 16:00-20:00 on the diurnal cycle.(2) The maximum soil moisture was distributed in the depth of 20-30 cm, while the minimum was distributed in the surface layer(0-10 cm) for three different vegetation coverage. Besides, the soil moisture content had a positive relationship with the vegetation coverage, especially in the surface layer(20 cm).(3) The evaporation had a negative relationship with the aboveground biomass.(4) According to the relationship between evaporation and meteorological elements, the result shows that evaporation was mainly affected by water vapor pressure and net radiation.
引文
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[2] 宿梅双,李久生,饶敏杰.基于称重式蒸渗仪的喷灌条件下冬小麦和糯玉米作物系数估算方法[J].农业工程学报,2005,21(8):25-29.
[3] Trenberth K E,Smith L,Qian T,et al.Estimates of the global water budget and its annual cycle using observational and model data[J].Journal of Hydrometeorology,2007,8(4):758-769.
[4] 吴荣军,葛琴,詹习武,等.基于遥感-过程耦合模型的地表蒸散量应用研究[J].生态环境学报,2013,22(6):1001-1008.
[5] Jie L I,Sha J,Wang B,et al.Evaporation and its energy exchange in Alpine meadow ecosystem on the Qinghai-Tibetan Plateau[J].Journal of Integrative Agriculture,2013,12(8):1396-1401.
[6] 白军红,欧阳华,徐惠风,等.青藏高原湿地研究进展[J].地理科学进展,2004,23(4):1-9.
[7] 戚培同,古松,唐艳鸿,等.三种方法测定高寒草甸生态系统蒸散比较[J].生态学报,2008,28(1):202-211.
[8] Miehe G,Miehe S,Bach K,et al.Plant communities of central Tibetan pastures in the Alpine steppe/Kobresia pymaea ecotone[J].Journal of Arid Environments,2011,75(8):711-723.
[9] 陈仁升,康尔泗,杨建平,等.内陆河流域分布式水文模型-以黑河干流山区建模为例[J].中国沙漠,2004,24(4):416-424.
[10] 陈仁升,吕世华,康尔泗,等.内陆河高寒山区流域分布式水热耦合模型(Ⅰ):模型原理[J].地球科学进展,2006,21(8):806-818.
[11] 郭燕红.色林错湖面蒸发对湖泊水量平衡贡献的观测与模拟研究[D].北京:中国科学院大学,2016.
[12] 李王成,王为,冯绍元,等.不同类型微型蒸发器测定土壤蒸发的田间试验研究[J].农业工程学报,2007,23(10):6-13.
[13] 王根绪,沈永平,钱鞠,等.高寒草地植被覆盖变化对土壤水分循环影响研究[J].冰川冻土,2003,25(6):653-659.
[14] 马颖钊.青藏高原中部(安多)坡面尺度季节冻土土壤水分特征及其对地表升温的响应[D].北京:中国科学院大学,2014.
[15] 郭燕红,张寅生,马颖钊,等.藏北羌塘高原双湖地表热源强度及地表水热平衡[J].地理学报,2014,69(7):983-992.
[16] 张立锋,张继群,张翔,等.三江源区退化高寒草甸蒸散的变化特征[J].草地学报,2017,25(2):273-281.
[17] 高扬子,何洪林,张黎,等.近 50 年中国地表净辐射的时空变化特征分析[J].地球信息科学学报,2013,15(1):1-10.
[18] 高春娟,夏晓剑,师恺,等.植物气孔对全球环境变化的响应及其调控防御机制[J].植物生理学报,2012,48(1):19-28.
[19] 王利辉,何晓波,丁永建.青藏高原中部高寒草甸蒸散发特征及其影响因素[J].冰川冻土,DOI:10.7522/j.issn.1000-0240.2017.0392.
[20] 高云飞.黑河上游天老池流域亚高山草地蒸散发研究[D].兰州:兰州大学,2016.