桂西北主要退耕还林模式土壤水文—物理性质研究

退耕还林是退化生态系统重建的重要途径.对桂西北地区12种退耕还林模式3 a植被恢复期林地土壤水文一物理性质进行了定位监测研究.结果表明,(1)不同土壤深度(0-20 cm,20-40 cn,40-100 cm)的平均土壤容重为0.824～1.256 g/cm2,分别比农作物地增大2.4%～4.4%,其中0-20 cm土层的差异达到显著水平.(2)土壤非毛管孔隙度、总孔隙度和通气度的平均值依次为1.1%～21.3%,52.4%～59.8%和28.3%～35.7%,分别比农作物地下降4.1%～20.7%,其中非毛管孔隙度0-20 cm土层的差异达到显著水平;毛管孔隙度的平均值为38.5%～41.3%,比未退耕地增大5.2%～7.6%.(3)1 m土层内的最大持水量、毛管持水量、最小持水量依次为43.0%～58.3%,37.0%～48.4%和30.5%～38.2%,分别比农作物地降低1.3%～10.5%,但差异不显著.(4)1 m土层退耕还林地土壤有效贮水量为1 652.6～2 294.3 t/hm2,比农作物地提高1.9%～5.9%,但两者的差异不显著.

Soil Hydrological and Physical Properties for Main Patterns of Converting Farmland into Forestland in Northwest Guangxi Province

Converting cultivated land into forestland is an important way for the reconstruction of degraded ecosystem.Soil hydrological and physical properties on 12 converted lands in Northwest Guangxi Province after 3 year reconstruction were observed.Results showed that the averaged soil densities in different soil layers(0-20,20-40,and 40-100 cm)were 0.824~ 1.256 g/cm³,which increased by 2.4%~ 4.4%compared with cropland.Soil density within 20 cm of the surface soil reached a significant level.The averaged soil non-capillary porosity,total porosity,and ventilation were 1.1%~ 21.3%,52.4%~ 59.8%,and28.3%~ 35.7%,respectively.Soil non-capillary porosity within 20 cm of the surface soil reached a significant level.The averaged capillary porosities were 38.5%~ 41.3%,which increased by 5.2%~ 7.6%compared with original farmland.The maximum water holding capacity,the capillary water holding capacity,and the minimum water-holding capacity in the 1m layer were 43.0%~ 58.3%,37.0%~ 48.4%,and 30.5%~ 38.2%,respectively,which had no significant differences.The effective storage capacities in the 1m soil layer on converted farmland were 1652.6%~2294.3t/hm²,which increased by 1.9%~ 5.9%compared with cropland,but the differences were not significant.