Spatial distribution and simulation for fine roots of triploid Populus tomentosa with wide and narrow row spacing.

Abstract

To form a basis for constructing a root-water-uptake model of triploid Populus tomentosa，spatial distribution characteristics of fine roots were studied through wide （6 m） and narrow （2 m） row spacing planting schemes，and soil coring method using correlation，regression and variance analyses. Results showed that vertically，in both wide and narrow spaced rows，the fine roots were mainly concentrated within the 0 － 20 cm soil layer where their amount were 0.080 cmcm-3 and 0.074 cmcm-3 accounting for 44.1% and 48.7% of the total，respectively. For a radial distance of 100 cm from the stem，the fine root length density of 0 － 20，20 － 40，40 － 60 and 60 － 80 cm soil layer in a wide row increased by 35.45%，36.76%，71.67% and 72.27% as compared with that of the corresponding soil layer in a narrow row. Horizontally，in the wide row fine root length density from 20 － 200 cm showed an exponentially declining distribution. The fine roots were mainly concentrated within the 20 － 80 cm soil zone，and within the 0 － 200 cm range these roots were 0.250 cmcm-3 occupying 49.20% of the area. The fine roots in the narrow-spaced row were distributed irregularly with no significant differences among the fine root length densities for different radial distances. In addition，a one-dimensional （R2 = 0.228） root length density function was fitted to narrow spaced rows，while the two-dimensional （R = 0.538） was fitted to the wide row.［Ch，5 fig. 2 tab. 12 ref.］