Effects of terracing with Platycladus orientalis plantations on water budget in the dryland of Loess Plateau in China

Abstract

Terracing engineering and vegetation plantation have been implemented in many water-limited areas, aiming to reduce the effect of drought, conserve water, and promote ecosystem restoration. However, due to the complexities of slope structure, the major hydrologic processes controlling the water balance of terraces are still unclear. To further quantify the role of terraces on water retention in the stand scale, in a normal year (2015) and a dry year (2016), we compared the water balance for the combination of Platycladus orientalis with zig terrace (PZ), fish scale pits (PF), and natural slope (PN) in a typical loess hilly area of China. Our results indicated that terracing was an effective way to increase water retention and reduce runoff. After the growing season, compared with PN, terraced fields enhanced the water budget with 13.6–21.3 mm for PZ and 2.4–11.7 mm for PF. In addition, terraced fields generated less runoff (a reduction of 45.3–60.8 % for PZ and 19.6–26.6 % for PF) and more soil water storage (an increase of 18.5–24.1 % for PZ and 13.6–14.7 % for PF) than the natural slope. Overall, the water budget of all plots was positive (29.6 mm for PZ > 20.0 mm for PF > 8.3 mm for PN) in the normal year (2015) and negative (−49.6 mm for PZ > −60.8 mm for PF > −63.2 mm for PN) in the dry year (2016). Our results suggest that precipitation is still the primary factor affecting the water budget in woodlands, and terracing measures can help to improve the utilization of precipitation and enhance soil water retention in the Loess Plateau.