黄土丘陵区不同密度人工油松林土壤水分状况研究

Soil Moisture of Artificial Pinus tabulaeformis Stands with Different Densities in Loess Hilly Region

以黄土丘陵区不同密度的人工油松林为对象,通过野外观测资料分析了其土壤含水量的季节及年际动态。结果表明：（1）研究期内降雨量主要集中在6-9月,占到全年降水量的80%以上,1-4月仅占当年降水量的3.2%~17.0%,表现出春旱严重;（2）林地土壤含水量随降雨量具有明显的季节和年际变化,并表现出1-2个月的滞后期,旱季不同密度的人工油松林地土壤含水量差异较小,雨季及生长季末差异明显,0~300 cm土层平均土壤含水量均表现出小密度林地显著高于中密度和大密度林地（P〈0.05）。（3）3种不同密度林地的土壤含水量垂直分布具有相似规律,均随土层深度增加而显著减低（P〈0.05）。

From the field investigation,the seasonal and interannual dynamics of soil moisture in artificial Pinus tabulaeformis stands with different densities in the Loess Hilly Region were studied.The results showed that the rainfall mainly happened from June to September,accounting for 80% of a year.Precipitation from January to April accounted for 3.2%-17.0%,and caused severe spring drought.There were significant seasonal and annual variations of soil water content in rainfall reason,and showed 1-2-month lag.The differences of the soil water content with different sample sites in dry season were not obvious,but significant during the rainy season and the end of growing season.The average soil water content in 0-300 cm layer in the small-density site was significant higher than those of others（P〈0.05）.There were similar rules of soil moisture vertical distribution among three sample sites,and it was getting lower significantly with the increase of soil depth（P 〈0.05）.