Effectiveness of nature-based solutions (NBSs) has received considerable attention at the United Nations Food Systems Summit (UNFSS), which concluded in September of 2021, and COP26 of UN Framework Convention on Climate Change in Glasgow in November of 2021. However, research information about on-the-ground application of NBSs is scanty. There are several social, economic, institutional, and policy barriers to widespread adoption of approaches and strategies to NBSs. Poor institutional readiness and lack of mechanisms to reward farmers/land managers through payments for strengthening ecosystem services (ESs) are among critical issues that need to be addressed. Translation of science into on-the-ground action necessitates close cooperation of researchers and extension staff on one side, with the private sector, policy makers, and land managers on other. Farmers and ranchers must be rewarded for provisioning of key ESs strengthened through the adoption of NBSs, such as for sequestering carbon (C) in soil and vegetation, improving renewability and quality of water resources, strengthening of biodiversity, and adopting nutrition-sensitive agricultural practices.
INTRODUCTION TO NATURE-BASED SOLUTIONS
Soil degradation is a global issue of the 21st century. The extent of global soil degradation is estimated at about one-third of all land (IPBES 2019). It affects the wellbeing of 3.2 billion people and costs an equivalent of 10% of world’s annual gross product in 2010. Over 90% of all soils could become degraded by 2050. Estimated rates of soil erosion on arable or excessively grazed lands are 100 to 1,000 times higher than natural erosion rates, with up to 50% loss in crop yield (FAO and ITPS 2015). The UNFSS reported that 811 million people in the world faced hunger in 2020, which was a 20% increase in one year due to the COVID-19 pandemic. Soil degradation is also a major contributor to climate change, and temperatures of 1.5°C and 2.0°C (2.7°F and 3.6°F) above the preindustrial level may occur during the 21st century (IPCC 2018). Thus, protection, restoration, and sustainable management of soils is a high priority.
It is in this context that NBSs are being widely proposed and were specifically mentioned by the secretary general in his report of the UNFSS (UN 2021). NBSs encompass, but are not limited to, protection, conservation, restoration, management, enhancement, or imitation of natural ecosystems (Osaka et al. 2021). NBSs involve living organisms (i.e., plants and microorganisms) to perform critical functions, such as that of soil and water bioengineering interventions. The strategy is to create innovative relationships between human and natural elements, processes, and functions with the aim of restoring degraded soils and natural resources (Fernandes and Guiomar 2018). These options exploit natural mitigation processes to recover nutrients and restore resource quality (Mancuso et al. 2021). Basically, NBSs are innovative options that are inspired from nature (Padma et al. 2019) and specifically applied to global issues, such as soil degradation and its restoration.
NBS is a Euro-centric term that refers to technological options inspired, supported, and duplicated (copied) from nature (Spyrou et al. 2021). The strategy is to avoid large-scale and expensive interventions that lead to drastic perturbations with strong adverse implications. This approach can address complex issues, such as mitigation of floods (Han and Kuhlicke 2021). Simply put, NBSs are technological approaches that reflect cooperation with nature while also being cost-effective, resource-efficient, and simultaneously causing environmental and social improvements (Andrikopoulou et al. 2021). NBSs also positively impact ecological landscape quality and provide multiple benefits, such as enhancing natural capital, strengthening biodiversity, reducing water runoff, improving water retention in the root zone, increasing terrestrial C sequestration (e.g., soil vegetation), and enhancing adaptation to and mitigation of climate change (Fritz 2017). NBSs are measures to convert anthromes into more nature-compatible and efficient options that cause less degradation and create new biodiversity hotspots (Fernandes and Guiomar 2018). NBSs comprise of solutions that use plants and microorganisms (living organisms) to perform functions that reduce conflicts between natural processes and human needs (Fernandes and Guiomar 2018). These technologies are inspired, supported, and copied from nature (Spyrou et al. 2021).
The concept has been adopted by the European Commission (Pauleit et al. 2017) but has ignited debate among researchers as to the effectiveness of using nature as a viable solution for mitigating the impacts of anthropogenic perturbations on environmental issues (Collier 2021), such as soil quality. One of the constraints is paucity of data on long-term effectiveness of NBSs on soil health and the ESs that it can create. Thus, the objective of this article is to deliberate feasibility of NBSs to address relevant global issues of the 21st century and to cite some specific examples of pertinent land use and soil management practices.
SOIL-BASED ECOSYSTEM SERVICES
Soil-based ESs are goods and resources generated by soil, and some examples of using NBSs to strengthen ESs are outlined in figure 1. Based on several case studies, Keesstra et al. (2018) showed the potential of NBSs to serve as cost-effective and long-term options for minimizing risks of hydrological imbalance and soil degradation. Keestra and colleagues classified NBSs into two categories: soil solutions, and landscape solutions. Whereas soil solutions restore soil quality and functions to strengthen local ESs, landscape solutions address the idea of interconnectivity or the nexus-thinking. Increasing interconnectivity of the landscape may reduce losses by surface runoff, sediment transport, and nutrient loading. This would increase soil moisture reserves, reduce drought, decrease soil erosion, and enhance sustainability. Sustainable management of soil, via restoration of soil organic C content and stocks and improvement in soil quality and functionality, directly impacts Sustainable Development Goals or the Agenda 2030 of the UN (Lal et al. 2021a).
Relevance of nature-based solutions to addressing some global issues of the 21st century.
SOIL QUALITY AND FUNCTIONALITY
Several soil functions have strong impacts on ESs of relevance to human and nature. Some pertinent among these functions are soil water infiltration, water retention, structure and porosity, gaseous diffusion, and C storage. Some NBSs can deliver multiple benefits through improvements in soil physical, chemical, biological, and ecological quality (table 1). However, the challenge lies in reframing of the nature-human relationship with the goal of regenerating or restoring soil quality and functionality through strengthening of the co-dependence between human and nature, which forms the basis of human wellbeing and environmental quality (Welden et al. 2021). Keesstra et al. (2018, 2021) promoted the concept of connectivity and the systems thinking framework to advance sustainability and enhance ESs. Keestra and colleagues advocated organic farming in Spain, rewilding in Slovenia, land/soil restoration in Iceland, sediment trapping in Ethiopia, and wetland construction in Sweden. They documented that NBSs are long-term solutions to curtail soil and land degradation and reduce hydrological risks. In boreal forests, Houle et al. (2016) assessed nutrient cycling and drought and observed that droughts have unexpected impacts on nutrient cycling through effects on tree canopy and soils leading to loss of potassium (K) from boreal forest ecosystems. NBSs are measures that strengthen cooperation with nature and enhance resource efficiency (Andrikopoulou et al. 2021), leading to positive impacts on ecological landscape quality by providing multiple benefits (Sowinska-Swierkosz et al. 2021). The strategy is to achieve alignment of environmental and social goods (Fritz 2017). Lehman et al. (2015) emphasized the role of soil biology, specifically microbiology, in protecting crops from pests and diseases, and managing droughts.
Some examples of technological options involving nature-based solutions.
WATER QUALITY AND RENEWABILITY
NBSs are also pertinent to addressing drought/flood syndrome and water scarcity. In central Greece, Spyrou et al. (2021) used natural water retention measures to moderate the drought/flood syndrome. The NBS implemented decreased the maximum depth and velocity of flooding and reduced the flooded area, but favored long-term groundwater recharge. Rather than simply adopting afforestation and less-intensive agriculture, Hewett et al. (2020) proposed catchment system engineering based on a holistic view of catchments and proactive interventions to strengthen ESs. Kiedrzyńska et al. (2021) suggested river system retentiveness to strengthen multi-dimensional environmental sustainability to reduce extreme hydrological events. Kiedrzyńska and colleagues proposed water, biodiversity, ES, resilience, culture, and education benefits by adopting a holistic approach to multifunctional reservoir design. Jerzy et al. (2020) observed that adoption of NBSs reduces the economic costs of water retention by 85.9% for local social groups. Biomanipulation methods are also used to avoid or reduce cyanobacterial bloom development in rivers, ponds, and lakes (Triest et al. 2016). Vörösmarty et al. (2018) propoesd ecosystem-based engineering systems to provide cost-effective solutions to advance water security and included protected areas, water observatories, etc. The strategy is to use NBSs involving plants and microorganisms (Fernandes and Guiomar 2018). Rey (2021) proposed merging security with ecology to advance co-benefits of NBSs at catchment scale for harmonizing flood prevention and erosion control with restoration of biodiversity. Use of perennial herbaceous plants is also effective for hillside erosion mitigation (Apollonio et al. 2021).
ADAPTATION AND MITIGATION OF CLIMATE CHANGE
Application of NBSs is also being promoted for adaptation to and mitigation (ADAM) of global warming. Gallotti et al. (2021) promoted a series of open-air laboratories in Finland, Greece, the United Kingdom, Italy, and Ireland to cope with specific hazards including floods, drought, landslides, salt intrusion, and nutrient and sediment loading. Gallotti and colleagues concluded that use of intensive forestry, marine seagrass, water retention ponds, live cribwalls, and high density plantations of woody and deep-rooted herbaceous vegetation are effective NBSs. The rewetting of peatlands and establishment of wetlands are important strategies for ADAM of global warming (Taillardat et al. 2020; Beyer et al. 2021). In Chile, Hoyos-Santillan et al. (2021) proposed diversification of ADAM including wetland; peatland; biodiverse, treeless habitats; and native forest ecosystems. In the Coastal Plain of North Carolina, Hovis et al. (2021) proposed potential flood reduction practices such as cover cropping with no-till (NT) farming, hardpan breakup, pine or hardwood afforestation, agroforestry, wetland construction/restoration, grass and hedges wetlands, forest wetlands, stream channel restoration, dry dams and berms, tile drainage, and water retention. Hrabanski and Le Coq (2022) proposed three terms: climate smart agriculture, agroecology, and NBSs for climatization of agricultural issues. Of these three, agroecology is a long-standing term.
SALINITY MANAGEMENT
Salinization, primary and secondary, is among major threats to agricultural ecosystems and is being aggravated by the current and projected climate change. Rocha et al. (2020) proposed the use of cyanobacteria as a tool for restoration of saline ecosystems through the ability of those organisms to fix C and nitrogen (N) and enhance soil stabilization. In four eco-regions of southern Australia, Lefroy et al. (2005) proposed the adoption of perennial plant-based farming systems for management of soil salinity. Perennials are useful for improving the vegetative cover, food source and habitat for native biota, and enhancing structural complexity composition. However, they may introduce new weeds.
HUMAN HEALTH, WELLBEING, AND FOOD SECURITY
Humanity is faced with the challenges of the depletion of natural capital, security of food, energy and water, and human health and wellbeing. Faivre et al. (2017) argued that these challenges are strongly intertwined with global processes including climate change and natural disasters. However, these challenges can be addressed by adopting NBSs that optimize synergies between nature, society, and economy, and NBSs can turn these challenges into innovative opportunities (Faivre et al. 2017). Urban/home gardens are important to strengthening local food production systems (Lal et al. 2020; Lal 2020). Over and above provisioning of fresh food, urban gardens also contribute to water regulation, improved air circulation, and cooling through plant transpiration and shading (Fritz 2017). Urban gardens reduce the heat island effect and moderate the temperature. Hamidov and Helming (2020) proposed the water-energy-food nexus for sustainable management of natural resources. However, (Lal et al. 2017) suggested the food-energy-water-soil nexus to strengthen the interconnectivity and advance food security.
IMPLEMENTING NATURE-BASED SOLUTIONS
Whereas the relevance of NBSs for addressing some global issues is widely recognized (Seddon et al. 2020), there are challenges and barriers to implementation of these options at different scales. Some actions for implementing NBSs are outlined in table 2.There is a strong need to identify and establish the underpinning factors, such as policy framework, end users’ interests, and participation in NBS design and operationalization (Kumar et al. 2020).
Actions needed to address challenges and barriers to the implementation of nature-based solutions (NBSs).
To be successful, Dekker et al. (2021) proposed that NBSs must build upon the proven contributions of well-managed and diverse ecosystems to strengthen resilience of human societies. Examples of proven contributions of well-managed and diverse ecosystems may include alternatives to techno-industrial solutions that can enhance social-ecological integration by providing simultaneous benefits to nature and society. Indeed, there may be several barriers to their adoption, such as lack of successful examples, lack of finances, and lack of business models (Mayor et al. 2021), among others. Thus, there is an urgent need for development of business models and business cases to catalyze investments for NBSs. In this context, Mayor and colleagues proposed a tool entitled “Natural Assurance Schemes” to attract funding. Similarly, Beierkuhnlein (2021) proposed some proactive NBSs for mitigating risks and reducing adverse effects of extreme weather events and natural hazards. Rather than implementing the strategy immediately, Beierkuhnlein proposed the need for developing long-term and spatial concepts, and urged the need for installing the currently missing governance structures based on geographical, geoscientific, ecological, meteorological, and social expertise. These innovations are essential prerequisites to translating science into action.
CONCLUSIONS
Usefulness of NBSs for addressing global issues is widely recognized. However, examples of on-the-ground application of these approaches are few and even rare. Important among global issues are anthropogenic climate change, soil degradation by diverse processes (e.g., soil erosion, salinity, soil organic C depletion), water contamination and scarcity, ecosystem disservices or decline, loss of biodiversity, food and nutritional insecurity, and risks to human health and wellbeing. Examples of some proven technologies based on approaches/strategies of NBSs include, but are not limited to, perennial grain crops, agroecology, regenerative agriculture, soil and water bioengineering, wetland establishment and restoration, biochar, catchment management, agroforestry, interconnectivity or the nexus approach, field boundary hedgerows, eco-hydrology, and more (figure 2). Approaches to NBSs are aimed at using nature to address current and emerging issues. However, there are numerous barriers and challenges to upscaling and mainstreaming NBSs, including lack of clarity among concepts and approaches to NBSs, lack of governance framework, disconnect between people and nature, poor institutional readiness, lack of law and policy instruments, and lack of catalyzing innovations. Additionally, there is a need to develop mechanisms of payments to farmers for strengthening ESs through adoption of NBSs. Translating science into action necessitates close cooperation between researchers, the private sector, policy makers, and land managers.
Nature-based solutions include (a) establishing vegetated buffers in riparian zones and (b) planting commodity crops, such as corn, into cover crops. Photo credits: (a) USDA photo by Bob Nichols and (b) Indiana Natural Resources Conservation Service photo by Brandon O’Connor.
- Received February 4, 2022.
- © 2022 by the Soil and Water Conservation Society