Biological Contribution of Ornamental Plants for Improving Slope Stability along Urban and Suburban Areas

Alessandra Francini,Daniela Romano,Stefania Toscano,Antonio Ferrante,Francesco Ferrini

doi:10.3390/horticulturae7090310

Alessandra Francini, Daniela Romano + Show 3 more

Open Access

https://doi.org/10.3390/horticulturae7090310

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Abstract

Plants can reduce erosion during heavy raining periods and improve slope stability through their root morphology, development, biomass, and architecture. Heavy rains can increase erosion, becoming a danger for traffic and people who live around slopes. The control of slope stability is often required in urban and peri-urban environments, and for this reason ornamental species can be appropriately selected for a dual use, namely improving the aesthetical value of green areas along the urban and suburban roads and mitigating the erosion effects. The species used must have good tolerance to abiotic stresses, such as high and low temperature, drought, pollution and nutrient deficiency. Otherwise, their limited growth can reduce their beneficial effects. Ornamental plants that can be used for reducing the erosion of slopes must be in full growth during periods with a higher incidence of rains and must also be compatible with the temperature ranges in different seasons. These species can be also selected for their ability to avoid erosion and enhance the stability of slopes. In this review, the biological contribution of plants for improving slope stability has been reported and discussed with a special focus attention on the Mediterranean environment. Particular emphasis has been placed on root biomass changes and root growth parameters, considering their role as potential markers for selecting suitable plants to be used for enhancing slope stability. A brief description of planting on slopes and root growth has been also considered and discussed.

Highlights

Urban and peri-urban green areas provide important ecosystem services for the quality of the urban environment such as air pollution mitigation, direct effects on local climate, noise abatement, stormwater management during rainy periods, carbon dioxide assimilation, oxygen supply, and recreational and social benefits [1]
The current review has the objective of highlighting the biological contribution of ornamental plants to increasing slope stability
The root system is an integral plant organ involved in the acquisition of nutrients and water, the synthesis of plant hormones, organic acids, and amino acids, and it is necessary to ensure the anchorage of plants [22,23]

Summary

Introduction

Urban and peri-urban green areas provide important ecosystem services for the quality of the urban environment such as air pollution mitigation, direct effects on local climate, noise abatement, stormwater management during rainy periods, carbon dioxide assimilation, oxygen supply, and recreational and social benefits [1]. The stability of soil in planted slopes depends on the interaction of roots of different species that can synergistically work or have antagonist effects. The increase of the slope induces responses growth and growth modifications Mechanical stresses such as wind, rain, and gravitational force in sloping conditions influence root growth and their distribution, as mentioned above. Root growth under different slope degree has not been sufficiently detailed and this knowledge gap can represent limitations for plant species selection for practical applications. Inaasloped slopedsoil, soil,the theaerial aerialpart part and and roots roots tend tend to to align align vertically vertically during during responses growth It means that plants in slope conditions have canopy and roots distrigrowth (Figure 2A).

Plants

Root Morphology and Slope Stabilization

Root Physiology and Development under Abiotic Stress

Use of Plant Growth Regulators and Biostimulants for Increasing Root Biomass

Use of Ornamental Plants for Slope Greening

Limitations and Research

Findings

Conclusions and Outlook