Temporal stability of soil moisture under effect of three spacings in a eucalyptus stand

ABSTRACT. Soil moisture temporal variability is an important concept in understanding forest management. The objective of this study was to analyse the effect of planting density on soil profile moisture in a clonal Eucalyptus plantation. Soil moisture was observed every 15 days at 25 points distributed throughout the eucalyptus stand between November 2013 and October 2015 to characterize the moisture according to the following three types of spacings: 3 x 2, 3 x 3, and 3 x 5 m. At each point, the 0 - 10, 10 - 20, 20 - 30, 30 - 40, and 60 - 100 cm layers were evaluated using a Profile Probe PR2 model. Soil moisture showed high spatial variability in the 0 - 10 cm layer, whereas from 30 to 100 cm deep, the moisture tended to become more homogeneous throughout the area. The dry periods presented greater temporal soil moisture stability when compared to the rainy seasons. The 3 x 2 m spacing has greater temporal soil moisture stability when compared to the others, while the 3 x 3 m spacing presented greater temporal variability.

摘要：土壤水分时间变异性是森林经营管理研究中的重要概念。本研究旨在分析种植密度对无性系桉树人工林土壤剖面水分的影响。2013年11月至2015年10月期间，研究人员在整片桉树人工林内布设25个观测点，每15天开展一次土壤水分观测，以表征3×2 m、3×3 m及3×5 m三种株行距配置下的土壤水分特征。每个观测点均采用Profile Probe PR2型剖面水分仪，对0~10 cm、10~20 cm、20~30 cm、30~40 cm及60~100 cm土层的土壤水分进行测定。0~10 cm土层的土壤水分表现出较高的空间变异性，而30~100 cm深度范围内，土壤水分在整个研究区域内趋于更加均一。相较于雨季，旱季的土壤水分时间稳定性更强。其中，3×2 m株行距配置的土壤水分时间稳定性高于其余两种配置，而3×3 m株行距配置的土壤水分时间变异性则更为显著。