Effects of soil compaction in skid trails on seedling architecture and dry biomass allocation in oak Quercus castaneifolia C.A.M. seedlings in greenhouse conditions

Heavy soil compaction may impose a serious threat to soil ecosystem functioning.The penetration resistance reduces the elongation and penetration of roots and thus lowers the uptake of water and nutrients. This study used a soil strength (penetration resistance) experiment in a greenhouse to test the hypotheses that increasing soil strength would adversely alter seedling architecture by changing above- and below-ground biomass allocation patterns. The effects of soil compaction were explored in a loam to clay-loam textured soil with optimal conditions of water on a continuous scale (0.1–1.0 MPa penetration resistance) on biomass allocation responses and architecture of the deciduous Quercus castaneifolia (C.A.M.). Results showed that below-ground metrics of fresh and dry biomass (main and lateral root biomass) were negatively affected by soil compaction. Increasing soil strength did not change above- and below-ground biomass allocation patterns (i.e., root mass ratio, root: shoot ratio, specific root length), resulting in unchanged seedling architecture. It is concluded that in loam to clay-loam textured soil with optimal conditions of water and soil strengths of up to 1.0 MPa, increasing soil compaction did not cause significant growth allocation patterns to above- and below-ground portions leading to architectural changes in the seedlings, concluding that plant architecture was found to be less sensitive to increased soil compaction than size/growth and hence not a very reliable predictor of size/growth responses.