Nature's Solutions for Sustainability

The United Nations Economists Network in its publication Nature Based Solutions suggests it as a simple and cost effective strategy for addressing imminent environmental and societal challenges. Based on the researchers like Griscom, Busch and Fuss et. al publications the the article claims the NBS as highest potential in solving societal and environmental problems. For example the total net mitigation potential of NBS might exceed 23 thousand Tg CO2e per year which is just little shorter than 30 thousand Tg CO2e of mitigation required per year between now and 2030 to keep the temperature below mean global warming. It is estimate that NBS could mitigate this CO2 at the cost of less than 100 USD per ton. the major question raised by these scientists is whether that potential will be realized and how? The forest sector accounts for two-thirds of the mitigation potential followed by agriculture and wetlands. Reforestation and forestry management practices need to be augmented.

"Areas that are reforested, farmed less intensively, or otherwise maintained in a more natural state may hold greatest mitigation potential" says United Nations Economist Network,

Monetary and Physical Benefits

As the climate change results in temperature and sea level rise the NBS will protect us from storms and erosion and will give relief from heat. It could also help in pollution treatment and provision of habitat for biodiversity, pollinators for crops, and a host of others. The UNEN lists following benefits of the Nature Based Solutions:

1. Carbon sequestration in biomass in vegetation and soils; biodiversity protection; flooding, drought, and erosion protection, recreation and tourism, water infiltration and storage
2. Provision of fuel and forest products to local users; flooding, drought, and erosion protection
3. Sustainable income; water infiltration and storage; reduced pressure on natural forests, slope stabilization
4. Protecting lives and property from storms and flooding; carbon sequestration; enhancement of biodiversity and fisheries production
5. Maintenance of soil fertility; pollinator habitat; storm protection; shading, enhanced food security; cooling; storm water control; pollution reduction; carbon sequestration

Social, health and happiness related benefits

It is also important to consider the social and health benefits along with monetary or physical benefits. For example Biodiversity and Ecosystem Services Network suggests that Nature Based Solutions not only offer monetary and physical benefits and scenic beauty but also offer health and happiness.

1. Forests are natural air purifiers. Trees absorb pollutants and produce oxygen leading to cleaner, fresher air, which is beneficial for respiratory health.
2. Forests encourages physical activities such as hiking, walking or jogging which are excellent for cardiovascular health and overall fitness.
3. Trees emit substances called phytoncides, which have been found to boost immune system function. Breathing in these substances during a forest walk can enhance the bodies natural defences
4. Some studies suggests that forests have therapeutic effects on chronic diseases and conditions like hypertension, diabetes and certain stress-related disorders.
5. Spending time in sunlight helps the body produce Vitamin D, which is essential for bone health and has ben linked to lower risk of certain diseases.

Strategies to realize the potential of Nature Based Solutions

Maintenance

Further from the references of Garzuglia and Saket 2005 the publication claims that about half a million Tg of carbon is maintained in earth’s vegetation; most of this is stored in forests. This forest carbon stock represents close to 50 years’ worth of CO2 emissions at current levels. Maintaining mature natural forests or other ecosystems without disturbance prevents the release of carbon dioxide from their vegetative biomass and these soils. The substantial amount of carbon is stored in the forests and other ecosystems. It was estimated that the forests have a carbon storage value of more than 50,000 USD per hectare and timber values alone would generally not justify clearing mature forest land. These pristine natural areas need to be preserved for following reasons:

• People around the world get the benefit of the carbon sequestration benefits in the form of forestalling climate change, where as the benefits of timber and other materials are taken away by a limited elite group.
• The most vulnerable groups including women and girls, on whose land forests stand have to find the alternative land and are more vulnerable to changes in their surroundings.
• Larger areas of habitat shelter more species diversity because large predators need large prey populations. Interconnected areas of diverse habitat may also facilitate seasonal movements of migratory species, as well as providing conduits for movement in response to climate change
• Preserved natural habitats may, then, also generate important conservation benefits by protecting biodiversity. Such a biologically productive areas supports megafauna like elephants and rhinoceroses, may promote carbon storage by seed distribution, fire suppression and other mechanisms.

Restoration

Though the natural forests can store large quantities of carbon their limited tracts and continuous deforestation can be compensated by regrowth of such systems. The estimates by Houghton and Nassikas (2018) shows that carbon sequestration in regrown in former farming areas may exceed 4,000 Tg per year. If the international community compensated landowners for this sequestration at the rate of 100 USD per ton of CO2 the yearly income generated globally would be greater than the GDP of nations such as Indonesia and Mexico and some 130,000 Tg of carbon could eventually be stored in regrown forests. However to achieve the 130,000 Tg of additional carbon storage some five percent of dry land on earth – an area larger than India. There could be a number of both economic and ecological limitations of a program on such a scale.

By halting and reversing the degradation of lands and oceans, we can prevent the loss of 1 million endangered species. Scientists say restoring only 15 per cent of ecosystems in priority areas can cut extinctions by 60 per cent by improving habitats.

Restoration is key to the prosperity and well-being of people. Vibrant ecosystems provide benefits from food and water to health and security that our growing population needs today and will need in the future.

Eight Key Ecosystems that We can Restore

The UN Decade on Ecosystem Restoration focuses on eight major types of ecosystems that we have dangerously degraded. Each can be restored by reducing the pressures they face and with on-the-ground action to speed their recovery says UN Environment Program

1. Forests

Plant native trees in degraded forests and on former forest land, assist natural regeneration and nurture trees and woodlands within human-dominated landscapes

2. Oceans and Coasts

Stop unsustainable fishing, restore coral, seagrass, mangroves and other habitats and remove plastic waste and pollution

3. Urban Areas

Put green spaces at the heart of urban planning, clean up urban waterbodies and mobilize citizens to restore private and public spaces

4. Freshwater

Treat waste water and prevent pollution, remove or improve dams and manage fishing, mining and water extraction sustainably

5. Peatlands

Prevent peatland drainage and conversion, re-wet degraded peatlands and control grazing and fuel-harvesting

6. Farmlands

Reduce tillage and using cover crops, adopt natural fertilizers and pest control and grow more diverse crops, including trees

7. Mountains

Restore forests to protect against avalanches, landslides and floods, limit extraction and excavation and build climate-resilient farming systems

8. Grasslands and Savannahs

Graze sustainably and reconnect habitats, clear invasive plant species and work closely with communities

The Global Gains of Restoration

• Climate Mitigation: Restoring forests, peatlands and mangroves, along with other natural solutions, can provide over one-third of the greenhouse gas mitigation needed by 2030.
• Climate Adaptation: Nature’s power can help us adapt to climate change. Restoring coastal wetlands on the Gulf Coast of the United States of America could avoid $18 billion in storm damage by 2030.
• Economy: Halting the decline of ecosystem services could prevent losses of $10 trillion in global income by 2050
• Food Security: Restoration through planting trees on farmland could increase food security for 1.3 billion people.
• Water Supplies: Forest restoration and better farm practices could cut the pollution of water supplies for 81 per cent of cities globally.
• Health: Adding urban trees can cut risks from pollution and heat while boosting mental and physical well-being for billions of people.
• Biodiversity: Restoring 15 per cent of converted lands in priority areas could avoid 60 per cent of expected species extinctions

Rotational Harvesting and Agriculture

Putting Carbon Back Where It Belongs the UNEP Foresight Brief 2019 underscores the importance of the agricultural practices and its potential in carbon storage in soil and plants, increasing soil fertility, water-holding capacity, improving yields and nutrition, creating drought-tolerant soils, restoring degraded cropland and grasslands and nurturing biodiversity, with positive consequences on local economies.

The Problem of Industrial Agriculture

The Foresight Brief Report of UNEP titled Putting Carbon Back Where It Belongs noted that, though the industrial agricultural system become successful in producing large volumes of food for the global market, this production is at the cost of significant soil erosion, biodiversity losses, pollution of freshwater bodies, too much reliance on the agro-industry and its products, enormous freshwater and nitrogen footprint and contribute about 25% global GHG emissions, decrease soil fertility, and heavily depends on fossil fuels and kills the pollinators. Some of the important points associated with the industrial agriculture are as follows:

• In many regions, soil fertility has been decreasing for decades, and large amounts of fertile soil have been (and continue to be) washed into rivers, lakes and oceans - gone forever, and with it, much carbon, originating from the oxidation of soil organic matter (SOM, commonly known as “humus”), has been released into the atmosphere in the form of CO2 , all of these with severe economic implications.
• Twenty-four billion tonnes of fertile topsoil (equivalent of a land area almost the size of Greece or Malawi or 192 million train wagons full of soil, every year is lost every year. Along with this topsoil loss is the ever-increasing degradation of agricultural soils. Twenty-five percent (25%) of the earth’s surface has already become degraded.
• A third of the CO2 emitted through human activities into the atmosphere from 1850 to 1998 came from agricultural activities. Estimates range between 133 gigatonnes of carbon (GtC) since the dawn of agriculture through loss of soil organic matter and soil erosion and 379 GtC through forest clearing and burning. In general, 50-70% of soil carbon stocks have been lost in cultivated soil.

The report raises the question "If large parts of that CO2 in the atmosphere come from the land and the soils, can it somehow be recaptured"? That is, can CO2 be re-sequestered in the soil or living organisms, and help mitigate climate change? The report suggests versatile methods to regenerate soil resources and sequester carbon through following agricultural practices:

No Tillage System

As tillage is one of the most important drivers for the mineralization of SOM and soil erosion, changing to reduced or no-tillage systems can have a positive impact on soil organisms and SOC, and can save up to 70% of energy and fuel costs and machinery investment. No tillage system should be supported by diverse multi species cover crop with deep reaching roots that transfer carbon to surface, stabilize soil and suppress weeds.

Crop Management Practices

This include selection of crop species and varieties with greater root mass and with deeper roots, use of crop rotations, cover crops during fallow periods and addition of compost and biochar.

Cover crops

The growing of beneficial plants as cover crops during season and for times of rest - and crop rotations or crop diversity can improve soil fertility and soil life, fix nitrogen to the soil through nitrogen-fixing plants, reduce soil erosion and suppress weeds as well as pests. The crop diversity can lead to higher yields, less pesticides use due to decreased weeds and insect pests by supporting natural enemies of pests. Deep rooted crop species sequesters more carbon, help break up bigger chunks, circulate nutrients, aerate the soil, provide beneficial conditions for earthworms and other soil life.

Crop Residue Retention

Earthworms keep soil porous, aerated, healthy, help infiltration and storage of water, increase humus levels through the integration of organic material in the soil and their highly nutrient-rich castings, and bring nutrients from lower strata to surface. Hence improving the number of earthworms and their maintenance in the soil is essential. Crop residue retention and mulching are key approaches suggested to improve soil carbon and soil fertility, limit soil erosion and increase the number of earthworms.

Intercropping

Intercropping is a simultaneous production of multiple crops on the same area of land, can increase net plant growth, sequester more carbon and suppress weeds. The report Putting Carbon Back Where It Belongs from the reference of Oelbermann claims 47% rise in SOC after years in maize/soybean strip rotation in comparison to 21% and 2% increase in single crop cultivation. This is because of the higher leaf surface area, increased mycorrhizal activity, increased porosity because of root networks and utilisation capacity of different plants for different mineral nutrients.

Undersown Growth

Undersown which is a living mulch helps to protect soil when the main crop does not fully cover the soil. It helps to suppress weeds and can, boost the main crops’ growth due to furnishing organic nitrogen and increase SOC.. This undersown produces energy in summer when all the grains are ripening and stop photosynthesis. Thus it provides not only carbon but also produce pollen, seeds and nectar to the birds and advance biological pest control.

Compost Application

The application of compost to crop- and grass-lands stimulates both above- and below-ground NPP and - even if applied only once - leads to increased carbon accumulation of 2-5 Mg C/ha over subsequent years. It augments soil life through the fungi and bacteria in the compost itself. And it stimulates soil life activity, while bringing additional carbon and nutrients to the soil, improving soil structure and water holding capacity at the same time.

Native Grass Pastures

Pastures are often replanted in a regular manner with low-rooting species which help putting carbon - very deeply into the soil. Whereas typical seeded grasses reach depths of not more than 50 cm, native plants easily grow several meters deep.

Crop Livestock Integration

Crop-livestock integration, that is, using animals to graze off cover crops or stubbles can increase SOM as well as economic return, diversify agricultural production systems, improve drought resistance and reduce soil erosion. It also improves the soil through bacteria- and nutrientrich excrements, and can be used as substitute for the herbicides. Along with crop livestock integration pasture cropping system which combines perennial pastures with the annual crops gives impressive results in terms of soil carbon increase and improved biodiversity and yields.

Improved Grassland Land Management

Improved grassland land management such as lower stocking rates, several types of rotational or short duration grazing, seasonal grazing, inclusion of legumes and a high variety of plants, can lead to sequestration of up to 1.8 GtC and annually.

Agroforestry

Agroforestry, the intentional integration of trees and shrubs into crop and animal farming systems can create multiple environmental, economic and social benefits. It can increase SOC and sequester between 0.2 and 5.3 GtC per year in soils. It also increases biodiversity, stabilizes the soil, improves water infiltration and diversifies the farmer’s yields. The addition of trees to agricultural mitigation practices such as conservation agriculture or managed grazing can increase carbon sequestration rates by 5–10 and increase soil carbon stocks by 3–10 times.

Intensive silvopasture systems - combining trees, livestock and grazing - can be developed to increase SOC and to achieve a net carbon capture (thus, accounting for the animals’ methane production) of 4-12 tC/ha/yr, while at the same time increasing the production of meat and milk on the same area of land.

Afforestation, by converting marginal and degraded agricultural soils into forests and perennial land use, can enhance the SOC and living carbon pool and has many other advantages like food through nut or fruits, fiber, fuel, mulch, reduced soil erosion, increased water infiltration etc., Trees have an extensive root system that can grow deeply into the soil and probably the most important source for SOC storage. However, afforestation cannot be developed at the expense of cropland, as it would compromise food security.

Reforestation

Reforestation measures have similarly a great potential and could account for 1-2.7 GtC/year globally. Through the selection of perennial food producing shrubs and trees, global food production could be improved. Globally, the carbon dioxide removal potential through afforestation and reforestation is significant and has been estimated at 1-3.2 GtC per year.

Restoration of histosols

Peatlands (with soils called “histosols”) are very high in organic matter and store large amounts of the world’s terrestrial biological carbon pool. While the carbon stocks have been partially depleted through drainage and tilling, there is significant potential of avoiding additional carbon losses histosols restoration. Long-term sequestration rates in histosols range from 0.3 - 1.3 GtC globally. However, histosol restoration implies stopping to crop them, which imposes a difficult trade-off between food production and other ecosystem services.

Biochar

Biochar, produced through pyrolysis of biomass, is a long-term stable form of charcoal. Biochar has multiple benefits such as stabilization of organic matter, improved soil fertility and soil quality, promotion of fungi and bacteria growth, improved water and nutrient retention, decreased pathogen impacts, increased soil porosity and higher crop yields. Biochar can also form long-term carbon pools in the soil sequestering up to 0.5 GtC/ year globally.

Thus the report Putting Carbon Back Where It Belongs highlights five principles of soil carbon storage and regenerative agriculture and emphasize the global community to bring them under regular practice. These include:

1. Always protect the soil surface

2. Minimize soil disturbance

3. Use high diversity of plants and animals

4. Keep living plant-root networks

5. Integrate animals into the crop

Clearly, putting the above-mentioned methods into practice is challenging, as they require much knowledge and need to be adapted to local conditions. Some of these efforts will take several years of persistent implementation in order to demonstrate reliable results, and the bearing of financial risks and critiques from the more conservative farmer community. There already exists a small although increasing number of farmers using (some of) these techniques, and with positive results. The chances rise that others will follow. Interest for field days of those innovative farmers is rising steadily around the world-UNEP