降水年型对黑土区土壤水分动态变化的影响

利用长期定位试验,研究了黑土区不同降水年型下荒地、裸地和农田土壤水分的变化特征.结果表明,降水年型能够影响不同植被类型下土壤水分的季节性动态变化和垂直变化.丰水年不同植被类型土壤含水量均呈"v"型曲线变化,最低值出现在7月份,观测期内裸地较高;平水年呈"W"型曲线变化,分别在6月份和8月份出现两个低值,不同植被类型表现为裸地>荒地>农田;枯水年除裸地在观测后期土壤含水量略有增加外,荒地和农田均持续下降.降水年型对土壤水分变异系数的影响表现为枯水年>平水年>丰水年.其中荒地土壤水分变化最为剧烈,表现在枯水年出现了速变层,而在丰水分内次活跃层也较农田向土壤深层延伸,其次为农田和裸地.

Impact of Different Yearly Rainfall Patterns on Dynamic Changes of Soil Moisture in Black Soil Region

Based on long-term experiment, the dynamic change of soil moisture in grassland, bare land and farmland in black soil region under effects of different yearly rainfall patterns was analyzed. The result showed that dynamic and vertical changes of soil moisture under different land-covers were effected by different yearly rainfall patterns. In rainy year, change of soil moisture under different land-covers presented "V" type, the lowest value was found in July, bare land was higher than grassland and farmland in observed period; soil moisture in normal year varied in "W" type, two low value were found in June and August, respectively, different land-covers decreased in the order of bare land > grassland > farmland; in dry year, grassland and farmland decreased continually in observed period, while bare land had a little of increase in late period. The effect of different yearly rainfall patterns on variance coefficient of soil moisture decreased in the order of dry year > normal year > rainy year. Because fast-changing layer of soil moisture was found in grassland and its second active layer were deeper than farmland in rainy year, so, change of soil moisture of grassland was the best active, followed by farmland and bare land. In observed period, soil presented status of supplying water, amount of supplying water of dry year, normal year and rainy year were 103. 2 mm,38. 8 mm 和 23. 3 mm, respectively.