Spreading topsoil encourages ecological restoration on embankments: soil fertility, microbial activity and vegetation cover

PLoS One. 2014 Jul 1;9(7):e101413. doi: 10.1371/journal.pone.0101413. eCollection 2014.

Abstract

The construction of linear transport infrastructure has severe effects on ecosystem functions and properties, and the restoration of the associated roadslopes contributes to reduce its impact. This restoration is usually approached from the perspective of plant cover regeneration, ignoring plant-soil interactions and the consequences for plant growth. The addition of a 30 cm layer of topsoil is a common practice in roadslope restoration projects to increase vegetation recovery. However topsoil is a scarce resource. This study assesses the effects of topsoil spreading and its depth (10 to 30 cm) on two surrogates of microbial activity (β-glucosidase and phosphatase enzymes activity and soil respiration), and on plant cover, plant species richness and floristic composition of embankment vegetation. The study also evaluates the differences in selected physic-chemical properties related to soil fertility between topsoil and the original embankment substrate. Topsoil was found to have higher values of organic matter (11%), nitrogen (44%), assimilable phosphorous (50%) and silt content (54%) than the original embankment substrate. The topsoil spreading treatment increased microbial activity, and its application increased β-glucosidase activity (45%), phosphatase activity (57%) and soil respiration (60%). Depth seemed to affect soil respiration, β-glucosidase and phosphatase activity. Topsoil application also enhanced the species richness of restored embankments in relation to controls. Nevertheless, the depth of the spread topsoil did not significantly affect the resulting plant cover, species richness or floristic composition, suggesting that both depths could have similar effects on short-term recovery of the vegetation cover. A significant implication of these results is that it permits the application of thinner topsoil layers, with major savings in this scarce resource during the subsequent slope restoration work, but the quality of topsoil relative to the original substrate should be previously assessed on a site by site basis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ecosystem*
  • Nitrogen / chemistry
  • Phosphorus / chemistry
  • Plants / metabolism*
  • Soil / chemistry*
  • Soil Microbiology*

Substances

  • Soil
  • Phosphorus
  • Nitrogen

Grants and funding

Grants were received from the Ministry of Science and Innovation's Centre for Industrial and Technology Development (CDTI). The project is jointly funded by Madrid Regional Government grants for research groups, REMEDINAL 2 from the Spanish Ministry of Science and Innovation, and assistance from the Torres Quevedo Sub-program for the employment of Dr. BMJ by OHL, under the auspices of the Ministry of Science and Innovation. Thanks also go to the Science and Innovation Ministry for the Salvador de Madariaga Mobility grant awarded to BP. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.