Effects of pit plantings on tree growth in semi-arid environments

Abstract

ABSTRACTThis study developed a pit planting technique in which only planting spots were dug to reduce earthwork costs and to enhance tree growth. This technique, in which pits of different depths were dug, was actually applied to a semi-arid experiment site to analyze its effects on soil moisture and tree growth. The soil moisture content in the pit planting 30 cm in depth (30 cm pit planting) and 50 cm in depth (50 cm pit planting) was 6.5 ± 0.1% and 6.7 ± 0.1%, respectively, which was at least 1.3 times higher (P < 0.01) than that of the control plot (surface planting). The crown growth rate of Populus sibirica trees for 2 years following the planting was 733.5 ± 43.3% in the 30 cm pit planting and 889.4 ± 58.5% in the 50 cm pit planting which, at their maximum, were 1.7 times higher than in the control plot. The stem diameter growth and the new shoot length were maximally 1.5 times better in the pit planting than in the control plot. The pit planting technique developed will be widely useful to promote the rooting and growth of trees in planting areas with problems of strong winds and dryness.