Connecting Global Priorities Biodiversity and Human Health

Case study: The use of vegetation in slope stabilization
In China, articial, human-made structures have traditionally been employed to protect communities
and infrastructure from shallow landslides, but these have short lifespans and have in many instances
caused considerable disruption to ecosystems. Ecological engineering involves “the design of
sustainable ecosystems that integrate human society with its natural environment for the benet of
both” (Stokes et al. 2014). The use of plants as ecological engineers represents a more cost–eective
and enduring option to combine with civil engineering approaches, with the potential of being selfsustaining,
increasing in ecacy over time, enhancing local biodiversity, and providing a plethora of
ecosystem services that can help address various drivers of livelihood vulnerability.
Several studies have shown that the establishment of certain types of vegetation cover signicantly
reduces shallow landslides and erosion on steep slopes (>35°) due to the ability of root systems
to modify the biophysical, mechanical and hydrological properties of soil (Stokes et al. 2010;
Reubens et al. 2007; Fattet et al. 2011; Ghestem et al. 2011; Mao et al. 2014). To be eective,
however, ecological engineering techniques require that the mechanical, chemical and architectural
traits of plant root systems be determined on a site-specic basis to determine optimum species
combinations and planting congurations for rehabilitating, protecting and stabilizing degraded
slopes (Stokes et al. 2014).
Certain species are traditionally favoured in slope stabilization – such as vetiver grass in China (Ke
et al. 2003), but monocultures can be a high-risk venture, thus favouring a mixture of dierent plant
functional types for slope stabilization, for example (Stokes et al., 2014; Fattet et al., 2011; Pohl et
al. 2009; Reubens et al. 2007). Polyculture plantations provide a range of root systems for optimum
soil stability. They also foster a heterogeneous environment for enhanced biodiversity and overall
ecosystem functioning, as well as supporting opportunities for income generation and a number of
other socioeconomic co-benets (Gouzerh et al. 2013; Shi and Li 1999; Post and Kwon 2000; Cavaillé
et al. 2013).
While ecological engineering usually does not incorporate, but can enhance the eciency of, humanmade
structures, another key distinction between these approaches relates to their eectiveness
over time and space. From the rst moment of hard engineering installation, no erosion should occur;
however, this ecological engineering relies largely on plant growth, leaving a window of susceptibility
during the early years of restoration of a site when plants are too small to fully contribute to soil
stability (Stokes et al. 2004; 2008).
Mitigation measures encompass, for example,
engineering techniques, improved environmental
policies and educational campaigns, and can be
implemented at a range of scales. At the household
level, awareness-raising schemes can encourage
an avoidance of unnecessary risks through
encouraging the preparation of emergency kits or
the procurement of personal insurance. At a larger
scale, the instalment of gas shut-off valves for
earthquake events or the construction of houses
on stilts to reduce flooding damage also comprise
common mitigation efforts, while early warning
systems may be established and building design
standards integrated into policy at the national
level.
Mitigation is linked to the concept of disaster
resilience, which describes the ability of a
system, community or society to resist, absorb,
accommodate and recover from the effects of a
hazard in a timely and efficient manner, including
through the preservation and restoration of its
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