Root development of young loblolly pine in Spodosols in southeast Georgia

Determining fine-root dynamics is fundamental to forest soil nutrient management yet root development of fast-growing loblolly pine (Pinus taeda L.) is poorly documented. The objectives of this study were to (i) investigate the spatial and temporal root development of loblolly pine; (ii) evaluate the relationship between root length, number of roots exiting a trench face, and root mass densities; and (iii) determine if there is a relationship between fine root and foliage mass as well as root and shoot mass during the early stages of stand development. Thirteen forest sites in southeastern Georgia covering ages 1 to 4 yr old were used. Roots temporal and spatial distributions were investigated using a trench method. The value of NX (# roots cm-2) was measured in August/September during the first 4 yr of stand development. Root density depth distributions fit a natural logarithm relationship with soil depth. An empirical model for root development over time was developed. A two-dimensional evaluation of root development showed that roots were present in 13 to >60% of the soil volume from Year 1 to Year 4. Regressions between root length density, LV (cm root cm-3 soil), and NX were included. Lastly, it was shown that the ratio of fine root mass/foliage mass was stable after the establishment phase, as was the ratio of root to shoot.