Soil compaction and water content as factors affecting the growth of lodgepole pine seedlings on sandy clay loam soil

The response of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelman.) seedlings to three levels of soil compaction and water content was evaluated in raised beds filled with a sandy clay loam soil. In compacted soils, seedling survival, height, root collar diameter and root growth were reduced. Soil water regime was adjusted with irrigation to levels associated with plant moisture stress (near wilting point) and limiting soil aeration (near 0.10 m(3) m(-3) air-filled porosity). Soil water regime affected seedling performance, with higher survival, root collar diameter and root growth observed on treatments with higher water content. Compaction had detrimental effects on growth at all levels of soil water availability. Compaction and water content had strong effects on soil mechanical resistance. Limitations to seedling growth and survival were at least partly explained through their relationships with soil water content and soil mechanical resistance, and combinations of these factors as described by the least limiting water range concept.