滴灌与沟灌栽培杨树人工林土壤水分动态与生产力

在北京大兴区永定河故道沙地上对9年生杨树人工林进行滴灌和沟灌栽培,于根系主要分布土层(20、40、60、80 cm)布设土壤水分传感器并利用智能采集器实时监测土壤含水率,分析不同灌溉措施下的土壤水分动态变化及杨树人工林生产力。结果表明: 单次有效的滴灌和沟灌后,沿树行形成的湿润体垂直深度分别为72和143 cm,湿润体横切面的面积分别为0.41和2.71 m²;灌溉量分别为79.20和776.47 m³·hm^-2,后者为前者的9.8倍,灌溉后杨树吸收根主要分布土层(0～40 cm)的土壤含水率下降到水分轻度亏缺临界值(土壤含水率为田间持水量的70%)的历时均为11 d左右。2019年4—10月,沟灌5、7、9月3次总灌溉量为2329.41 m³·hm^-2;滴灌18次,总灌溉量为1425.60 m³·hm^-2。沟灌下杨树人工林土壤水分中度亏缺(土壤含水率低于田间持水量的60%)累计天数达109 d,而滴灌下的杨树人工林土壤水分始终未发生中度亏缺。滴灌下杨树人工林蓄积年生长量为38.92 m³·hm^-2,是沟灌(25.43 m³·hm^-2)的1.5倍,表明不同灌溉措施下杨树人工林生产力差异显著。

Soil moisture dynamics and productivity of poplar plantations under drip and furrow irrigation managements

A 9-year-old poplar plantation was cultivated by drip irrigation and furrow irrigation in the sandland of ancient Yongding River in Daxing District of Beijing. Soil moisture sensors were set up in main soil layers (20, 40, 60 and 80 cm) with most roots distributed. The intelligent collector was used to monitor soil moisture in real time to investigate soil moisture dynamics and forest productivity under different irrigation patterns. The results showed that after a single effective drip irrigation and furrow irrigation, the vertical depth of wet body formed along the tree row was 72 cm and 143 cm, and the cross-sectional area of wet body was 0.41 and 2.71 m², respectively. The amount of irrigation was 79.20 and 776.47 m³·hm^-2 respectively, with the latter being 9.8 times of the former. The duration was almost the same (11 d) when soil moisture went down to the level of slight water deficit (the soil moisture content=70% of field moisture carrying capacity) in the 0-40 cm layer where poplar absorption roots mainly distributed. From April to October 2019, total irrigation amount of three times furrow irrigation in May, July and September was 2329.41 m³·hm^-2, and that of drip irrigation was 1425.60 m³·hm^-2, 18 times in total. There were 109 days during which poplar trees suffered moderate water deficit (the soil moisture content ≤60% of field moisture carrying capacity) under furrow irrigation, whereas no moderate water deficit happened under drip irrigation during the whole growing season. Annual increment of standing volume was 38.92 m³·hm^-2 under drip irrigation, which was 1.5 times of that under furrow irrigation (25.43 m³·hm^-2). Our results suggested that different irrigation resulted in significant difference in productivity of poplar plantation.