梭梭和沙拐枣对风沙土壤水热盐动态的影响

为揭示塔克拉玛干沙漠公路防护林不同植物类型下土壤水热盐运移规律,于2015年5—9月采用CS656土壤水热盐三参数传感器对防护林内梭梭和沙拐枣根区土壤水分、盐分和温度进行实时监测,分析了气温与土壤温度的相互关系和土壤水盐动态变化规律。结果表明:(1)梭梭和沙拐枣根区土壤温度基本一致,气温与土壤温度呈极显著相关(p0.01),各土层间土壤温度相关性随深度的增加逐渐减弱;(2)受灌溉制度影响,防护林土壤水盐呈现出明显的周期性变化规律,梭梭和沙拐枣根区土壤水盐动态变化趋势相似。在垂直方向上呈单峰曲线,其峰值分别位于30,10cm土层处。其中,梭梭林下土壤可分为水分速变层、弱变层和稳定层3个土壤层次,而沙拐枣林下土壤可分为水分速变层和弱变层2个土壤层次;(3)灌溉后土壤湿润体均呈"半椭球形"分布,梭梭和沙拐枣根区土壤灌溉水影响深度分别为60,150cm,而土壤盐分呈"表聚型"分布,但尚未造成土壤盐渍化(1.0 mS/cm);(4)6—9月份梭梭根区土壤平均贮水量(116.34mm)略大于沙拐枣(100.99mm),土壤水分亏缺明显,都大于270mm。

Effects of Haloxylon ammodendron and Calligonum mongolicum on Water-heat-salt Dynamics in Sandy Soil

Water-heat-salt dynamics in sandy soil are essential to design a reasonable irrigation schedule in the Taklimakan Desert Highway Shelterbelt.In order to reveal spatial and temporal rules of the water-heat-salt dynamic changes under different plant types in the region,based on the field investigation and real-time monitoring between May and September in 2015,we discussed the correlation between air temperature and soil temperature in the shelterbelt,and also analyzed the spatial and temporal dynamics of soil water and salt under different plant types.The results showed that:(1) Soil temperature was basically consistent under different plant types,and air temperature was significantly correlated with soil temperature (p ＜ 0.01).Meanwhile,the correlation of soil temperatures in different soil layers decreased as the soil depth increased.(2) In the soil of artificial shelterbelt,the dynamics of soil water and salt displayed an obvious periodic rule.With respect to Haloxylon ammodendron,the distribution of soil water and salt displayed a single-peak curve with the peak appeared at a depth of 30 cm,while the distribution of soil water and salt in the soil under Calligonum mongolicum showed a single-peak curve with the peak occurred at a depth of 10 cm.In the 0-200 cm soil profiles,soil moisture was divided into an active layer,a weak layer,and a stable layer in the soil under Haloxylon ammodendron,but only an active layer and a weak layer in the soil under Calligonum mongolicum.(3) The soil wetting front was a semi-ellipsoid shape after drip irrigation.The affected depth of irrigation water was 0.6 m in the soil under Haloxylon ammodendron,and 1.5 m in the soil under Calligonummongolicum.The soil salt was concentrated in the upper layer.However,soil salinization did not exist (EC was less than 1.0 mS/cm).(4) During the growing season,soil pondage was 116.34 mm in the soil under Haloxylon ammodendron,but 100.99 mm in the soil under Calligonum mongolicum.All the soil water deficit ullage was more than 270 mm.Plant types had minor influences on soil temperature.The irrigation of Calligonum mongolicum should be properly increased to maintain the health of the shelterbelt system.Our study is beneficial to provide a suitable irrigation system and approach,which can ensure the sustainable development of the shelterbelt system in the Taklimakan Desert.