Establishment and early growth of conifers on compact soils in urban areas

A study of pitch pine, Austrian pine, and Norway spruce on two different urban soils compacted to bulk densities of 1.2, 1.3, 1.6, and 1.8 g•cm-3 and maintained at high water potentials showed that all three species could become established from seed at high soil bulk densities. Pitch pine was the most suceessful species in establishment, Only a silt loam soil, packed to a bulk density of 1.8 g•cm-3, significantly reduced establishment of all three species. A sandy loam soil, also packed to 1.8 g•cm-3, did not reduce establishment. Root penetration was restricted at a bulk density of 1.4 g•cm-3 on the silt loam and 1.6 g•cm-3 on the sandy loam; there was a strong interaction between bulk density and soil type. Measured soil resistance to penetration may be a better indicator than bulk density for predicting seedling performance.