Consequences of soil compaction for seedling establishment: Implications for natural regeneration and restoration

Abstract

Soil compaction can affect seedling root development by decreasing oxygen availability and increasing soil strength. However, little quantitative information is available on the compaction tolerances of non-crop native species. We investigated the effects of soil compaction on establishment and development of two New Zealand native species commonly used in restoration programmes; Cordyline australis (Agavaceae) (cabbage tree) a fleshy rooted species, and Leptospermum scoparium (Myrtaceae) (manuka) a very finely rooted species. Seedlings were grown in a range of soil compaction levels in growth cabinet experiments. Low levels of soil compaction (0.6 MPa) reduced both the number and speed of C. australis seedlings penetrating the soil surface. In contrast, L. scoparium seedlings showed improved establishment at an intermediate compaction level. Root and shoot growth of both species decreased with increasing soil strength, with L. scoparium seedlings tolerating higher soil strengths than did C. australis. Despite these results, soil strength accounted for only a small amount of variation in root length (R 2 < 0.25), due to greater variability in growth at low soil strengths. Soil strengths of 0.6 MPa are likely to pose a barrier to C. australis regeneration. This is consistent with adaptation to organic and/or soft, waterlogged soils. Active intervention may be necessary to establish C. australis from seed on many sites previously in farmland.

Previous Land Use Affects the Recovery of Soil Hydraulic Properties after Forest Restoration

“…From this point of view, it is therefore important that monitoring forest restoration programs includes collection of soil compaction and K s data to understand the initial compaction degree and soil infiltration, reinforcing the need to compare these values with the pre-disturbance soil conditions. After assessing soil compaction and soil infiltration at the restored forests, management practices could be implemented to alleviate soil compaction, such as mechanical loosening techniques (i.e., deep ripping and subsoiling), which may improve plant growth [73,74]. In addition, some technical methods in forest restoration that have been shown to aid natural regeneration and soil recovery are the suppression of weedy vegetation and maintenance and enrichment planting [28].…”

Effects of soil compaction on seedling morphology, growth, and architecture of chestnut-leaved oak (Quercus castaneifolia)

“…Plants typically exhibit a wide range of responses to increased soil strength, i.e., physiological adaptations that affect morphogenesis, architecture, and nutrient and water use (Kozlowski 1999, Masle 2002, Bassett et al 2005. Shortly after soil strength increases, the elongation rate of primary and lateral roots decreases, the root cap generally becomes more rounded, and the root diameter behind the meristem (root tip) increases (Eavis 1967).…”

“…Shortly after soil strength increases, the elongation rate of primary and lateral roots decreases, the root cap generally becomes more rounded, and the root diameter behind the meristem (root tip) increases (Eavis 1967). As a consequence, morphological traits of roots can change: main roots become shorter and more lateral branch roots are formed, the proportions of fine roots and root xylem vessels are reduced, volume and weight of the root system decrease, and rooting depths become more shallow (Corns 1988, Misra & Gibbons 1996, Kozlowski 1999, Bejarano et al 2010, Alameda & Villar 2012. A smaller root system and more shallow rooting depths result in lower amounts of uptake of major nutrients and water, lower rates of transpiration and photosynthesis, and higher leaf water deficits (Kozlowski 1999).…”

Evolução dos processos ecossistêmicos em reflorestamentos da Floresta Estacional Semidecídua

“…Letra F representa as áreas dos fragmentos e a letra R as áreas dos reflorestamentos, está modificando a estrutura de compactação do solo nesse período inicial de desenvolvimento. Essa maior compactação do solo, nos reflorestamentos, favorece o desenvolvimento de espécies invasoras herbáceas (Bassett et al 2005), que são, a princípio, controladas mecanicamente por capina e roçada e, posteriormente, pelo sombreamento do subosque. No entanto, esse controle pode contribuir para retardar mudanças na compactação do solo, uma vez que a penetração de raízes está associada a mudanças na sua estrutura (Bassett et al 2005, Ruiz-Jaén & Aide 2005b.…”

“…Essa maior compactação do solo, nos reflorestamentos, favorece o desenvolvimento de espécies invasoras herbáceas (Bassett et al 2005), que são, a princípio, controladas mecanicamente por capina e roçada e, posteriormente, pelo sombreamento do subosque. No entanto, esse controle pode contribuir para retardar mudanças na compactação do solo, uma vez que a penetração de raízes está associada a mudanças na sua estrutura (Bassett et al 2005, Ruiz-Jaén & Aide 2005b. Desse modo, mudanças no grau de compactação do solo possivelmente só serão observadas após um longo período, e na medida do desenvolvimento da vegetação natural no subosque do reflorestamento.…”