Conifer Root Proliferation after 20 Years of Soil Compaction

Abstract

Soil compaction is known to limit plant growth by reducing soil macroporosity and restricting gas, water, and root movement. Recent evidence from study sites across the United States and Canada, however, suggests that tree growth is not universally affected by soil compaction from forest harvesting practices. Our observational study examined rooting patterns in mixed conifer plantations in the central Sierra Nevada of California to determine whether tree roots use continuous pathways or channels to overcome the physical restrictions of compacted soil. Replicate plots were established 20 -25 years earlier to compare compacted and uncompacted treatments after clearcut harvesting. Fine and lateral root counts were taken at multiple depths in soil trenches. Rooting was extensive in compacted plots despite consistently high soil strength values (ϳ3 MPa). No differences in rooting patterns or in fine or lateral root numbers were detected between compaction treatments. The results indicated long-term tolerance by conifer roots to soil compaction without clear use of preferential channels or uncompacted zones.

Soil Compaction and Productivity Evolution in a Harvested and Grazed Mediterranean Scots Pine (Pinus sylvestris L.) Forest

“…Moreover, the main impact of soil compaction on adult trees does not concern the expansion of their root systems but the renewal rate of fine roots or the availability of water in the surrounding soil. Busse et al (2017) [80] found no differences in rooting patterns or in fine or lateral root numbers between compacted and noncompacted areas in conifer forests 20 years after compacting treatments, suggesting a long-term tolerance of conifer roots to soil compaction.…”

The Recruitment of the Recalcitrant-Seeded Cryptocarya alba (Mol.) Looser, Established via Direct Seeding Is Mainly Affected by the Seed Source and Forest Cover

“…Conversely, although the semi-dense forest cover had slightly higher soil moisture in spring, the germination in this cover type was probably constrained by the higher bulk density. Soil compaction has been shown to reduce seed germination, root development, and survival in forest and grass species because it reduces macroporosity, gas exchange, water flow, and root exploration [ 53 , 54 ]. In a laboratory study, Skinner et al [ 55 ] found that compaction did not affect either the germination or the later mortality of Eucalyptus albens and Vulpia myuros .…”