祁连山林草复合流域气象因子、土壤特性及其蒸发对比研究

Comparative study on woodland and meadow of meteorological factors,soil properties and its evaporation in composite basin of Qilian mountains

土壤蒸发是森林生态系统水文循环的重要环节,也是流域水量平衡计算的难点,为此,在祁连山大野口流域对土壤特性、土壤蒸发和气象因子进行定位监测,对监测数据用相关系数法进行分析,结果表明:(1)林地比草地土壤年蒸发量低80.99%,林地土壤年蒸发量占降水量的54.16%,而草地占98.02%。在土壤蒸发旺盛期,林地和草地土壤蒸发量分别占全年的80.87%和85.47%;在土壤蒸发平稳期,林地和草地蒸发量分别占全年的19.13%和14.5 3%。(2)与各气象各因子相关性的平均值比较,林地比草低平均低出3.15%。(3)林地比草地土壤孔隙度、毛管孔隙度、非毛管孔隙度分别高出7.31%、7.63%、4.29%。本文通过林地和草地的土壤蒸发季节变化、土壤蒸发与气象因子相关性、土壤蒸发与土壤特性相关性等对比分析发现,虽然林地比草地土壤特性更有利于土壤蒸发,但气象因子是影响土壤蒸发的主成因子,林地形成的小气象环境抑制了土壤蒸发,使林地保持更多的水分供生长需要.本研究可为全面掌握森林生态水文学的水文循环机理和进行流域水量平衡计算提供科学依据和参考。

Soil evaporation was an important link of forest ecosystem hydrological cycle, and was also the difficult point in basin water balance calculation. Therefore, the soil properties, soil evaporation and meteorological factors in Dayekou Basin of Qilian Mountains were monitored and observed, and then the monitoring data were analyzed by adopting the correlation coefficient method. The results show that （1） Annual water evaporation in woodland soil was 80.99% lower than that in meadow soil, that accounted for 54.16%of annual precipitation, but the soil evaporation in meadow soil accounted for 98.02% of annual precipitation. During the apparent evaporation of soil, that in woodland and meadow soil s accounted for 80.87% and 80.87% respectively, and during the stationary phase of soil evaporation, that of woodland and meadow soils accounted for 19.13%and 19.13%respectively. （2） Compared with the mean value of correlation of each meteorological factor, the correlation of woodland was 3.15%lower than that of meadow. （3） The soil porosity and capillary porosity, non-capillary porosity of woodland soils were 7.31%, 7.63%and 4.29%respectively higher than that of meadow soil. Through comparative analyses on the seasonal variations of soil evaporation, relationship between meteorological factors and soil evaporation and correlation between soil evaporation and soil characteristics, the results indicated that although the soil properties of woodland were more conducive soil evaporation those of meadow, but the meteorological factor was the main factor that affected the soil evaporation, and the small meteorological environment formed on the woodland inhibited of soil evaporation, so this made the soil keeping more water to meet the need of tree growth. The findings provide scientific reference and basis for allsidedly grasping water cycle mechanism of forest ecological hydrology and making water balance calculation of the basin.