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Vol. 16 No. 4 - November 2010

Terrestrial Carbon Sequestration Through Mined Land Restoration

By: Anuj Kumar Singh1 and Jamaluddin2


The most important natural resource, upon which all human activities are based since time immemorial, is land. Man’s inexorable progress towards development has, however, considerably damaged our land resource base. Further, land also suffers from various kinds of soil erosion, degradation and deforestation. Mining is one of the reasons responsible for extensive land degradation in India and worldwide. The mining spoils, literally termed as dumps that result from excavation and dumping create stark hostile conditions for vegetatal growth and establishment. Mine spoils represent very rigorous conditions because of low organic matter content, low organic carbon, deficiency of soil nutrients, unfavorable pH, either coarse texture or compacted structures of spoil materials. As a result, the vegetation cover in and around mines is usually greatly reduced.  Regeneration through natural succession on such highly degraded sites is very slow and mostly results in a low diversity of plant communities. In the process of mines restoration, afforestation of spoils by suitable plant species supplemented with microbial Biofertilizers and certain mulches is a universally accepted technology. Afforestation of mined spoils not only serves the purpose of land restoration but also provides other very important ecological services like carbon sequestration and consequently greenhouse gas mitigation. Many research organizations and industries have been developing technologies to mitigate carbon dioxide (CO2) concentrations. The available options include separation and capture of CO2 from the energy system and sequestration in the deep ocean, sequestration in the geologic formations, sequestration in the depleted oil reserves, sequestration in the explored coal seam, and terrestrial sequestration in plants and soil. Out of many available technologies, afforestation approach is universally accepted due to its economic feasibility and practicability. Terrestrial ecosystems which consist of vegetation and soils are considered to be a major sink for carbon at present time. Carbon sequestration by plants is a natural process and does not require any specific sophisticated technological inputs. This article aims to discuss possibilities of carbon sequestration through afforestation approach of restoration of mine spoils spread almost in all states of the country.       

A brief on status of mining leases and wastelands in India

The status of mining leases as on 31.3.2007 indicates that 7,734 mining leases were under mining operations in the country in 23 states covering an area of 445,847 ha for 60 metallic and non-metallic minerals excluding lignite, coal, petroleum, natural gas, atomic minerals and minor minerals. During 2006-07, the state wise break up of leases indicates Andhra Pradesh is leading with 1,507 mining leases followed by Rajasthan (1,433), Gujarat (1,060), Madhya Pradesh (765), Tamil Nadu (461), Karnataka (455), Orissa (380), Jharkhand (323), Chhattisgarh (313), Maharashtra (262) and Goa (252).These eleven states together accounted for about 93% of the total mining leases in force.

Area wise, Rajasthan with 24% of mining lease area was ahead in 2006-07 followed by Orissa (14.89%), Andhra Pradesh (11.64%), Karnataka (8.30%), Jharkhand (7.80%), Gujarat (5.22%), Madhya Pradesh (4.66%), Goa (4.08%), Chhattisgarh (4.03%) and Maharashtra (3.82%). These ten states accounted for about 88.5% of the total mining lease areas in force and the remaining 11.5% was accounted for by the rest of the thirteen states. As on 31.06.2007, mineral wise, limestone ranks first with 1537 mining leases spread across the country covering an area of 106857.64 ha. Further, in addition to mined out areas there are a number of categories of lands lying unproductive and defined as wasteland. The estimates of extent of area suffering from land degradation vary from 38.40 Mha to 187 Mha National Remote Sensing Agency (now National Remote Sensing Centre) has estimated the extent of wastelands to be 63.85 Mha which is about 20% of the total geographical area. To harness the full potential of the available land resources and prevent its further degradation, wasteland development is of great significance. The problem of degraded land and its management is complex and multi-dimensional and its development requires a scientific, holistic and integrated approach.

Carbon dynamics in forests & plantations

The process of photosynthesis combines atmospheric carbon dioxide with water, subsequently releasing oxygen into the atmosphere and incorporating the carbon atoms into the cells of plants. Additionally, forest soils capture carbon. Trees, unlike annual plants that die and decompose yearly, are long-lived plants that develop a large biomass, thereby capturing large amounts of carbon over a growth cycle of many decades. Thus, a forest ecosystem can capture and retain large volumes of carbon over long periods. Forests operate both as vehicles for capturing additional carbon and as carbon reservoirs. A young forest, when growing rapidly can sequester relatively large volumes of additional carbon. An old-growth forest acts as a reservoir, holding large volumes of carbon even if it is not experiencing net growth. Thus, a young forest holds less carbon, but it is sequestering additional carbon over time. An old forest may not be capturing any new carbon but can continue to hold large volumes of carbon as biomass over long periods of time. Managed forests offer the opportunity for influencing forest growth rates and providing for full stocking, both of which allow for more carbon sequestration. Forest systems operate on a cycle of many decades and centuries, rather than annually or over a few years as would be the case with most crops and non-tree vegetation. As forest biomass expands, the amount of carbon contained in plant increases. As the biomass contract, the forest holds less carbon. In an unmanaged state, forests ebb and flow in response to disturbances in the natural system. Forest disturbance regimes are part of the natural ecological system, with wind, disease, fire and other natural, i.e., non-anthropogenic, events causing forest destruction and death. These events result in the release of carbon into the atmosphere but also are typically followed by the regrowth of the forest, which, in turn, begins a new process of carbon buildup in the forest. In some cases, these disturbances are catastrophic in that large areas of the forest landscape are disturbed, as with large wildfires such as are common in many pine and boreal forests. In other cases, the disturbances are highly localized, as with an occasional tree death due to disease or old age such as is common in many tropical forests. Carbon release is occasioned by the disturbance and often in the decay and decomposition of dead matter that follows. However, most natural forests have provisions for natural regeneration and regrowth, which, once again, captures carbon. Thus carbon is recycled in the forest ecosystem.

Afforestation Approach

 Soil acts as a critical controlling component in the development of any ecosystem. Mine spoils are not suitable for both plant and microbial growth because of low organic matter content, unfavorable pH, drought arising from coarse texture or oxygen deficiency due to compaction. The other limiting factors for revegetation of mine spoil may be salinity, alkalinity, poor water holding capacity, inadequate supply of plant nutrients and accelerated rate of erosion.   Numerous studies have demonstrated that land restoration benefits from plantations because it allows jump start succession. The catalytic effects of plantations are due to changes in under story microclimatic conditions (increased soil moisture, reduced temperature etc.), increased vegetational structure complexity, development of litter and humus layers and the soil physical and chemical environment and accelerating development of diversity on degraded sites. Plantations have an important role in protecting the soil surface from erosion and altering the accumulation of fine particles. They can reverse degradation process by stabilizing soil through development of extensive root systems. Plantation of suitable species speed up succession that fulfills revegetation goal. Besides controlling leaching of nutrients through soil erosion increases plant diversity. Earlier studies indicated that well adapted plant species could be recommended to establish self-sustaining cover, which require little maintenance activities. In restoration, emphasis is given first to build soil organic matter, nutrients and vegetation cover to accelerate natural recovery process. Plantation can be used as a tool for mine spoil restoration as well as carbon sequestration.  

Once plantation is established, plants increase soil organic matter, lower soil bulk density, moderate soil pH and bring mineral nutrients to the surface and accumulate them in available form. The plants accumulate these nutrients and re-deposit them on the soil surface in organic matter, from which nutrients are much more readily available for microbial breakdown. Once the soil characteristics have been restored, it is not difficult to form the full suit of self sustained plantation on mined lands. Some of the plant species viz. Jatropha curcas, Pongamia pinnata, Ailanthus excelsa and Withania somnifara have been successfully tried on limestone mined out areas of Madhya Pradesh in India. These important biodiesel and medicinal plant species are suitably surviving and also have attracted different other shrubs, grasses and tree species to grow. A number of restoration ecologists have suggested many approaches for restoration of mined land; however afforestation approach is uniformly accepted. The major aims of restoration of mined spoils should be:

  • Speedy development of vegetal cover capable of reducing erosion and pollution.

  • To provide ecological site stability in terms of favorable soil environment to support colonization of diverse flora and fauna

  • Enrichment of soil nutrient levels, weathering of overburden materials and humification of organic matter.

  • Bio-rejuvenation of soil system. Growth and survival of above ground and under ground flora.

  • Creation of self sustaining  ecosystem

Sequence of activities under afforestation approach 

I. Studies on mined lands, overburden dumps and spoils

            a) Ecological survey of major vegetative association and natural succession

            b) Characterization of mine spoils and dumps and identification of limiting factors for plant growth

II. Stabilization of sites through mechanical measures

III. Selection of site specific species suitable for the site

IV. Planting technique

V. Use of amendments – Application of biofertilizers, mulching, manuring, fertilization 

VI. Conservation of Moisture and water harvesting

VII. Protection, Monitoring and Evaluation

Selection of site-specific species suitable for the site

For sustainable stability of the ecosystem selection of most suitable species is important. The basis of species selection is:

  • Indigenous species of the particular eco-climatic or agro-climatic zone

  • Ecological survey  for identifying pioneering species of grasses, herbs, shrubs and trees

  • Species trial in nursery

The selected species should be

  • Capable of colonizing degraded areas

  • Fixing atmospheric N2 as well as conserving soil

  • Capable of attracting birds and other faunal population

  • Fast growing species should be given preference

  • Preference should be given to indigenous one over the exotic

Benefits of Mines restoration

Mine reclamation, reforestation, and forest management may provide ecological and economic benefits. Environmental benefits include reclamation of sites and storage of carbon in trees and soil. Beyond carbon sequestration, environmental benefits also include improved air and water quality, enhanced of wildlife habitat, reduction in soil erosion, and increased recreational opportunities.

Air Quality: Improvements in air quality generated by reforestation extend beyond the sequestration of carbon dioxide. Research has shown that reforestation benefits air quality in other ways. The leaf and needle surfaces of trees remove air pollutants such as nitrogen oxides, ammonia, and sulfur dioxide.

Wildlife Habitat: Reforestation of land after it has been disturbed by surface mining can produce valuable wildlife habitat by planting trees. This will in turn generate forest litter, which is an important part of the food chain and enriches the soil. The tree canopy moderates temperatures of rivers and streams, which aids the survival of aquatic species. Providing habitat for endangered and threatened species is another potential benefit.

Erosion and water quality: Reforestation can help remediate former mine lands by improving water quality. Tree roots stabilize mine land soil, which is susceptible to erosion. By stabilizing the soil, trees prevent sediment and nutrients from washing into nearby streams and rivers.

Phytoremediation: Revegetating   mining sites can be viewed as habitat improvement or the creation of a “living cap.” In addition, depending on the type of contamination present and the type of trees planted, revegetation can simultaneously provide a phytoremediation contribution. Phytoremediation is the use of vegetation for in situ treatment of contaminated soils, sediments, and water. Phytoremediation has an advantage of being less costly than many remediation alternatives. However, the process requires considerable time and should be employed at sites where remediation can occur over a long period of time. It is important to recognize that planting trees for carbon sequestration purposes does not equate to phytoremediation. Depending on the type of trees selected, reforesting a former mine land to generate carbon credits may do nothing to extract or remediate any existing contamination at the site. However, some tree types may serve to phytostabilize the soluble metals in the ground water or soil as well as creating a more suitable soil.

Biodiesel production feedstock. Apart from carbon sequestration and other environmental and ecological services; restoration of mined lands through afforestation may up to some extent provide India’s one of the big challenges of energy production. Afforestation of mined lands by energy plants viz. Pongamia pinnata and Jatropha curcas may prove as efficient utilization of wastelands particularly in tropical and sub-tropical ecological settings. After initial establishment, these species require nominal maintenance as both of the species are drought tolerant and well adapted to harsh climatic conditions.


While the debate over climate change continues, Government agencies, industry, and other organizations are pursuing proactive approaches to reduce atmospheric carbon, including carbon sequestration projects.  Mine reclamation through reforestation and sustainable forest management can provide two major benefits. Financial benefits include revenue from new forests, job creation, and other impacts on local economies. Environmental benefits include storing carbon in the trees and soil, enhancing wildlife habitat, and improving air and water quality. Thus, restoration of mined lands through afforestation adds to the planet's net carbon storage and helps moderate global warming by slowing the growth of carbon emissions in the atmosphere. Adoption of afforestation approach of mined lands restoration by appropriate technology and plants species preferably oil yielding species of Biodiesel importance are strongly recommended. Technologies like application of biofertilizers and mulches may be of great help for establishment of plants on mined lands. In this way, the waste of mines may be converted in wealth of mines and the loss what the mining has made to the environment will be sufficiently compensated.    

1Department of Forestry, Orissa University of Agriculture &Technology, Bhubaneswar-751003, ksanuj@live.com

2Emeritus Scientist (CSIR) Department of Bioscience, R.D. University, Jabalpur, M.P., jamaluddin_125@hotmail.com

This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.

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