干旱区杨树用材林土壤特性和林木生长对供水的响应

The Responses of Soil Properties and Tree's Growth to Irrigation in Poplar Timber Woodland of Arid Region

经过4年试验，结果表明，（1）供水对土壤水分调控作用明显，土壤各项含水指标均随供水量的增加而增加；（2）通过灌溉可改善土壤的三相比结构和土壤容重；灌溉对总孔隙度影响不明显；（3）灌溉对地下水位的影响显著，灌水前林地地下水埋深为3．46m，而灌水期内地下水埋深在2．36～2．87m之间，在7500m^3／hm^2·a灌溉定额以下时，不会造成土地次生盐渍化；（4）不同供水量对林木生长的效应是不同的，随灌溉量增加而造成不同程度的正增长；（5）人工林的蒸腾耗水量随供水量的增加而增加；（6）河套灌区杨树速生丰产林的合理灌溉量为7500m^3／hm^2·a。

4-year of research showed that： （1） Irrigation could regulate soil moisture parameters significantly, soil water content, soil water storage capacity, field water content and effective water amount increased following the increasing of irrigation amount. Effective water amounts afrer 1500, 4500 and 7500 （m^3/hm^2·a） irrigation were 1344 . 6, 2145.6 and 2441.8m^2 ; （2） Irrigation could improve soil texture and soil bulk density within 0-100 cm soil layer during the irrigation period. Soil bulk density values after 1500, 4500 and 7500 （m^3/hm^2·a） irrigation were 1. 45-1. 51,1. 41-1. 47 and 1.41-1. 44g/cm^2, and irrigation had little influence on total soil porosity; （3） Irrigation had significant influence on watertable. The watertable depth before irrigation was 3.46 m, while that during irrigation period was 2.36- 2.87m, when the irrigation was less than 7500（m^3/hm^2·a）, secondary soil salinization would not occur; （4） Tree＇s growth parameters had different responses to irrigateion amount. Compared to those with 4500 and 1500（ m^3/hm^2·a） irrigation, the timber volume with 7500 （ m^3/hm^2·a） irrigation increased by 10.57 and 48.26 percent, leaf area increased by 24.49% and 58.03%, root number increases by 67.58% and 129.32% respectively; （5） Water consumption by transpireation of woodland increased following the increasing of irrigateion amount. Annual water consumption amounts after 1500, 4500 and 7500 （m^3/hm^2·a） irrigation were 1225.7,1770.3 and 2966.6 m^3/hm^2, the water consumption coefficients per timber volume descended as 1500-4500-7500, and water production efficiencies ascended as 1500-4500-7500. The rational irrigation amount in Hetao irrigation areas should be 7500m^3/（hm^2·a）.