凝结水作为干旱半干旱地区重要的组分，对生物土壤结皮具有重要的生态学作用。为阐明高寒沙区青海共和盆地生物土壤结皮表层5 cm凝结水水汽来源，利用2017年5-9月自制微渗仪对土壤表层5 cm不同类型生物土壤结皮（苔藓结皮、藻类结皮、物理结皮）和流沙凝结水进行了观测。结果表明：高寒沙区凝结水量随结皮发育程度变化呈增加趋势，表现为：苔藓结皮>藻类结皮>物理结皮>流沙；生物土壤结皮覆盖区凝结水量显著大于流沙凝结水量，即生物土壤结皮有利于凝结水的产生；凝结水主要由吸湿水和大气水汽凝结水与土壤凝结水两部分组成；观测期间，不同类型结皮日土壤凝结水量无显著性差异；吸湿水量和大气水汽凝结水总量显著高于土壤凝结水量（P < 0.05）；随时间的变化，吸湿水和大气水汽凝结水与土壤凝结水对凝结水的贡献率呈波动性变化；吸湿水和大气水汽凝结水贡献率主要集中在65%~80%，土壤凝结水贡献率主要集中在20%~35%。
As an important source of moisture in arid and semi-arid regions, condensation water has significant ecological effect to the biological soil crust.For describing the source of condensation water in 5 cm of biological soil crust, we used micro-lysimeters to measure the amounts of condensation water in different types of biological soil crust and moving sand in Qinghai Gonghe basin.The results show that, condensation water generated almost every day except the windy and rainy days.In alpine sandy lands, the condensate water at different land cover types were significant different, and the condensate water was increasing with the development of crust:moss crusts > algae crusts > physical crusts > sand.The amount of condensation water in biological soil crust was significantly higher than that in moving sand, which proving that the biological soil crusts were beneficial to the production of condensation water.The condensate source was divided into two parts:the first was the air water vapor near the ground, including the natural moisture in the atmosphere and the moisture of the evapotranspiration in the plant and the soil, the natural moisture in the atmosphere and the moisture of the evapotranspiration condensed on the surface of the earth, the other was the water vapor in the soil gap, and the water vapor moved upwards in the lower layer of soil due to the temperature gradient of the night.The condensation water in biological soil crust was made up of three parts, hygroscopic and condensate water, atmospheric vapor condensate water, soil condenses water.During the observation period, no significant difference was found in daily soil condenses water in different types of biological soil crusts.And the hygroscopic and condensate water was significantly higher than soil condenses water(P < 0.05).The contribution rate to condensation water of hygroscopic and condensate water and soil condenses water had a fluctuated trend.The composition of condensate in the alpine sand lands was closely related to the relative humidity in the near formation at night, the peak air relative humidity in the near stratum was less than 80% at night, and the ratio of the contribution rate of the moisture absorption water and the atmospheric water vapor condensate to the soil condensate was about 2:1, and the contribution rate of the moisture absorption water and the atmospheric water vapor condensate to the soil condensate was about 4:1 when the relative humidity was higher than 80%.
[1]Agam N, Berliner P R, 2006.Dew formation and water vapor adsorption in semi-arid environments——A review[J].Journal of Arid Environments, 65(4):572-590.
[2]Boast C W, Robertson T M, 1982.A "micro-lysimeter" method for determining evaporation from bare soil:description and laboratory evaluation[J].Soil Science Society of America Journal, 46(4):689-696.
[3]Broza M, 1979.Dew, fog and hygroscopic food as a source of water for desert arthropods[J].Journal of Arid Environments, 2:43-49.
[4]Evenari M, 1981.Ecology of the Negev Desert, a critical review of our knowledge[J].Hepatology.
[5]Glenn D M, Feldhake C, Takeda F, et al, 1996.The dew component of strawberry evapotranspiration[J].Hortscience A Publication of the American Society for Horticultural Science.
[6]Gutterman Y, Shem-Tov S, 1997.Mucilaginous seed coat structure of Carrichtera annua and Anastatica hierochuntica from the Negev Desert highlands of Israel, and its adhesion to the soil crust[J].Journal of Arid Environments, 35(4):695-705.
[7]Kidron G J, Yair A, Danin A, 2000.Dew variability within a small arid drainage basin in the Negev Highlands, Israel[J].Quarterly Journal of the Royal Meteorological Society, 126(562):63-80.
[8]Subramaniam A R, Kesava R A V R, 1983.Dew fall in sand dune areas of India[J].International Journal of Biometeorology, 27(3):271-280.
[9]陈荷生, 康跃虎, 1992.沙坡头地区凝结水及其在生态环境中的意义[J].干旱区资源与环境, 6(2):63-72.
[10]陈荣毅, 魏文寿, 王敏仲, 等, 2015.古尔班通古特沙漠地表土壤凝结水形成影响因素分析[J].沙漠与绿洲气象, 9(1):1-5.
[11]方静, 丁永建, 2005.荒漠绿洲边缘凝结水量及其影响因子[J].冰川冻土, 27(5):755-760.
[12]郭晨露, 马耀明, 马伟强, 等, 2017.青藏高原珠峰地区戈壁下垫面上实际蒸散发量和蒸发皿蒸发量的关系研究[J].高原气象, 36(1):79-86.DOI:10.7522/j.issn.1000-0534.2015.00120.
[13]郭占荣, 韩双平, 2002.西北干旱地区凝结水试验研究[J].水科学进展, 13(5):623-628.
[14]李锋, 孙司衡, 2001.景观生态学在荒漠化监测与评价中应用的初步研究——以青海沙珠玉地区为例[J].生态学报, 21(3):481-485.
[15]李洪波, 白爱宁, 张国盛, 等, 2010.毛乌素沙地土壤凝结水来源分析[J].中国沙漠, 30(2):241-246.
[16]李新荣, 张元明, 赵允格, 2009.生物土壤结皮研究:进展、前沿与展望[J].地球科学进展, 24(1):11-24.
[17]刘文娜, 贾剑波, 涂志华, 等, 2016.北京山区林地凝结水特征研究[J].水土保持通报, 36(6):298-302.
[18]刘新平, 何玉惠, 赵学勇, 等, 2009.科尔沁沙地不同生境土壤凝结水的试验研究[J].应用生态学报, 20(8):1918-1924.
[19]潘颜霞, 2010.沙坡头人工固沙过程中吸湿凝结水形成特征研究[D].北京: 中国科学院研究生院.
[20]潘颜霞, 王新平, 张亚峰, 等, 2014.沙坡头地区地形对凝结水形成特征的影响[J].中国沙漠, 34(1):118-124.
[21]钱连红, 李洪波, 张国盛, 等, 2009.毛乌素沙地三种下垫面土壤吸湿凝结水量的比较[J].干旱区资源与环境, 23(3):122-125.
[22]王新平, 李新荣, 康尔泗, 等, 2003.腾格里沙漠东南缘人工植被区降水入渗与再分配规律研究[J].生态学报, 23(6):1234-1241.
[23]王哲, 梁煦枫, 王德建, 等, 2006.鄂尔多斯风沙滩地区土壤凝结水试验研究[J].地下水, 28(6):28-31.
[24]张静, 张元明, 周晓兵, 等, 2009.生物结皮影响下沙漠土壤表面凝结水的形成与变化特征[J].生态学报, 29(12):6600-6608.
[25]张晓影, 李小雁, 王卫, 等, 2008.毛乌素沙地南缘凝结水观测实验分析[J].干旱气象, 26(3):8-13.
[26]周娟, 文军, 王欣, 等, 2017.青藏高原季风演变及其与土壤湿度的相关分析[J].高原气象, 36(1):45-56.DOI:10.7522/j.issn.1000-0534.2016.00003.
[27]周亚, 高晓清, 李振朝, 等, 2017.青藏高原深层土壤热通量的变化特征分析[J].高原气象, 36(2):307-316.DOI:10.7522/j.issn.1000-0534.2016.00120.
