Soil Compaction and Growth of Woody Plants

Abstract

Although soil compaction in the field may benefit or inhibit the growth of plants, the harmful effects are much more common. This paper emphasizes the deleterious effects of predominantly high levels of soil compaction on plant growth and yield. High levels of soil compaction are common in heavily used recreation areas, construction sites, urban areas, timber harvesting sites, fruit orchards, agroforestry systems and tree nurseries. Compaction can occur naturally by settling or slumping of soil or may be induced by tillage tools, heavy machinery, pedestrian traffic, trampling by animals and fire. Compaction typically alters soil structure and hydrology by increasing soil bulk density; breaking down soil aggregates; decreasing soil porosity, aeration and infiltration capacity; and by increasing soil strength, water runoff and soil erosion. Appreciable compaction of soil leads to physiological dysfunctions in plants. Often, but not always, reduced water absorption and leaf water deficits develop. Soil compaction also induces changes in the amounts and balances of growth hormones in plants, especially increases in abscisic acid and ethylene. Absorption of the major mineral nutrients is reduced by compaction of both surface soils and subsoils. The rate of photosynthesis of plants growing in very compacted soil is decreased by both stomatal and non-stomatal inhibition. Total photosynthesis is reduced as a result of smaller leaf areas. As soils become increasingly compacted respiration of roots shifts toward an anaerobic state. Severe soil compaction adversely influences regeneration of forest stands by inhibiting seed germination and growth of seedlings, and by inducing seedling mortality. Growth of woody plants beyond the seedling stage and yields of harvestable plant products also are greatly decreased by soil compaction because of the combined effects of high soil strength, decreased infiltration of water and poor soil aeration, all of which lead to a decreased supply of physiological growth requirements at meristematic sites. Many protocols have been developed, with variable success, to alleviate the adverse effects of soil compaction on the growth and development of woody plants. These include planting of compaction-tolerant species, controlling vehicular and animal traffic, amending soils by adding coarse materials and/or organic matter, replacing compacted soils with uncompacted soils, loosening soils with aerating equipment, installing drainage systems and judiciously applying fertilizers. Prevention of soil compaction before planting is usually much preferred over post-planting treatments because the latter are expensive and difficult to apply, may not be adequately effective and may injure plant roots.

Plant Species Recovery on a Compacted Skid Road

“…Soil compaction can also severely reduce plant growth by restricting root growth may be due to oxygen stress and lower the percentage of water and air space in the soil [23]. Also, Kozlowski (1999) [24] mentioned a reduced total photosynthesis when soils become increasingly compacted, as a result of smaller leaf areas.…”

Effects of visitor pressure on understory vegetation in Warsaw forested parks (Poland)

“…Direct effects of such changes are the compaction of mineral soil particles and increased soil bulk density (Bhuju and Ohsawa 1998; Kozlowski 1999). In the case of urban woodlands, the differences in bulk density and soil compaction between RO and RR forest stands were insignificant suggesting that the cycling of organic matter were irrespective of age (Table 2).…”

Contribution of intercepted subsurface flow to road runoff and sediment transport in a logging‐disturbed tropical catchment

“…saprolite and bedrock in the study site) . Such surfaces provide very poor foundations for plant establishment and growth (Kozlowski, 1999). Furthermore, extended periods of surface wetting and wash caused by ISSF ( Figure 5) preclude successful colonization by vegetation (Pinard et al, 1996).…”