28 Ecosystem Degradation and Restoration

Sunil Mittal

1. Introduction

Historical prospects of ecological restoration

2.Definition of Ecological Restoration

3.Objectives of restoration

3.1 Time scales in restoration objectives

3.2 Ecosystem dynamics and Restoration

4. Different approaches used for the restoration of ecology

4.1Reclamation

4.2 Rehabilitation
4.3 Revegetation
4.4 Ecological engineering

5. Strategies of restoration

5.1 Natural recovery or passive restoration

5.2 Active or full restoration

6. Central concerns in ecological restoration

7. Terrestrial Ecosystem Restoration

8.  Restoration of aquatic ecosystem

9.  Ecosystem degradation and restoration

10.  Case studies related to restoration ecology in India Conclusion

1. Introduction

Throughout the centuries, environment has faced severe impacts and has undergone modifications to a greater extent due to natural and anthropogenic activities. However, the rate of environment and ecological degradation was highest in the past 50 years than any time in history. Anthropogenic activities like industrialization, energy exploitation, agriculture, mining and urbanization have significantly affected the structure and functions of ecosystems. The major causes of ecosystem degradation are:

Natural factors: In addition to these factors, some natural factors like storms, floods and wildfires also degrade the ecosystem in such a manner that it may not recover to its original state.

Biodiversity loss: Due to the degradation of the freshwater, land and marine ecosystems, the number of biological species is also decreasing. Thousands of animals and plant species have become endangered or threatened due to biological invasions, habitat loss and pollution. Deforestation, overgrazing, mining and waste disposal have degraded almost half of the Indian land mass.

Agricultural Practices: Bad agricultural practices have resulted in degradation of 56% of agricultural land leading to salinization, soil erosion and pesticide contamination. Forest ecosystems are experiencing degradation due to fire and invasive species, land use changes and tree felling.

Faulty land Use: Ecosystem gets damaged due to faulty land use management and disturbance of natural vegetation. Ecosystem degradation can occur at different levels due to soil erosion or vegetation destruction.

Pollution: Aquatic resources such as rivers, wetlands, streams and lakes are suffering degradation due to anthropogenic activities and release of pollutants by human activities .

There is an urgent need to protect coastal and marine ecosystems for the conservation of marine biodiversity. When an ecosystem loses its biodiversity, it starts showing degradation symptoms. Therefore, ecological restoration is mandatory for biological community and economic benefits of the people. One can say that ecological restoration serves as a research tool for sustainable development efforts and to support conservation.

Historical prospects of ecological restoration

• 1925: Nature’s guide to America was produced by Ecological society of America in North America. The guide was Victor Shelford.
• 1950: Nature conservancy was established. This conservancy was actively involved in the restoration of American grasslands and the predator species.
• 1935: Ecological restoration was taken up by civilian conservation corps at Arboretum of University of Wisconsin-Madison. The whole restoration program was carried out under the direction of Aido-Leopold. He was a great pioneer in conservation movement.
• 1982: Society for Ecological Restoration was established. The main aim of this society was to implement restoration activities on the basis of socio-economic consideration of affected people and ecological principles.
• 1998: Basically, restoration is a management that includes stewardship, preservation and conservation.

2. Definition of Ecological Restoration

Ecological Restoration is a process that assists in the recovery and management of ecological integrity. Ecological integrity includes variability in ecological processes and structures, sustainable cultural practices, and biodiversity.

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The process that helps in the recovery of damaged, destroyed or degraded ecosystem is termed as ecological restoration (Society for Ecological Restoration (SER), 2004). Recovered ecosystem contains sufficient biotic and abiotic resources so that its development is continued without any assistance.

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Return of a damaged ecosystem approximately to its original state is referred as ecological restoration.

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The process that deals with the renewal and maintenance of destroyed, damaged or degraded ecosystems is known as ecological restoration.

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From an ecological point of view, ecological restoration is an activity that reinitiates those ecological processes that were interrupted on the impairment of an ecosystem. From conservation point of view, ecological restoration refers to the recovery of biodiversity from an ecosystem that is facing human-mediated extinction crisis. From socioeconomic view, ecological restoration refers to the recovery of those ecosystem services from which people are benefitted.

From cultural view, ecological restoration is an approach that strengthens our institutions, communities and interpersonal relationships.

The most commonly used terms that define a restored ecosystem include ecosystem health and ecosystem integrity. Ecosystem integrity reveals the biodiversity characteristics in terms of structure, function and species composition.

3. Objectives of restoration

3.1  Time scales in restoration objectives

The most widely accepted definition of restoration is based on the drafting of the objectives. The concepts of reclamation and rehabilitation focus only on the functional aspects of an ecosystem, whereas concept of restoration interprets both the structural and functional aspects of an ecosystem. Since these two sets of variables are intimately connected, therefore it is very difficult to separate them. Therefore, theory and practice of restoration can also be used for reclamation and rehabilitation and vice-versa. The outcome of restoration practices can be anticipated hardly because of the dynamic nature of ecosystems. There are several examples showing that integrity of a disturbed ecosystem can hardly be reversed even in dynamic ecosystems. Two groups of objectives were drafted to solve the problem of restoration in dynamic restoration.

• One group of objectives focuses on short-term dynamics (years to decades). These may include recovery of unique species or functional group, and improving the functional properties such as soil retention of an ecosystem. Due to the specificity of these objectives, only suitable restoration techniques can be implemented.
• Second group of objectives including the recovery of the undisturbed ecosystem state can be achieved by autogenic succession.

b)   Ecosystem dynamics and Restoration

Restoration is basically linked to ecological succession. Consequently, the concept of restoration has evolved in conjunction with the existing paradigms of successional theory. Successional trajectories lead to the development of those communities that are dominated by some species that perform well in terms of productivity, resources retention, etc. There should be a crystal clear knowledge regarding to the ecosystem dynamics and ecology of the involved species so that the restoration models could be implemented in the real world. Restoration initiatives are time restricted and need to be implemented within a short period of time. Thus, there is no point in saying that the restoration should be halted until full details of ecosystem dynamics are known.

4. Approaches used for the restoration of ecology

The following approaches are used for restoration of ecology.

(a)    Reclamation

(b)   Rehabilitation

(c)    Re-vegetation

(d)   Ecological engineering

4.1 Reclamation: The process that deals with the minimization of the degradation process and making the severely damaged sites more habitable to living beings is termed as reclamation. The main aim of reclamation is to attain the pre-disturbance state.

4.2 Rehabilitation: It is another approach that aims to bring the damaged ecosystem to a functional one, irrespective of its original condition. Example includes the rehabilitation of forests. Rehabilitation can be partial also if only special attributes of the damaged site are restored.

4.3 Re-vegetation: The initial attempt to restore the structural and functional part of ecosystem is known as revegetation. In this approach, generally commercial plants are used. These plants may be native or non-native. This approach also involves the establishment of grass cover, seeding of shrubs and herbs on degraded sites so as to promote the wildlife. While doing re-vegetation, the use of locally adapted ecotypes is more beneficial. Gene pool of natural areas should be maintained near the restoration sites while reintroducing rare plant species and restoring sensitive habitats. However, this approach is applied only to large areas.

i)        The main objectives of re-vegetation are:

ii)      To control soil erosion

iii)    To enhance habitat space

iv)    To provide habitat for those species that are on the verge of extinction.

Physical characteristics such as aspect, organic material content, soil texture and water table depth should be taken into consideration before re-vegetation.

4.4 Ecological engineering: This approach involves the rebuilding of physical components of an ecosystem. Ecosystem functioning can be improved by installing hydrological devices such as drainage ditches and dams. The main aim of ecological engineering is to design, build and operate ecosystems so that the environmental problems can be solved. In this approach, eco-friendly techniques are designed.

Examples of ecological engineering approach are:

i) Wetlands have been constructed to deal with the problem of wastewater. Cattail, water hyacinth and common reed are most commonly used species in wetlands. Wetlands also treat the problem of acid mine drainage. These wetlands are made up of standing water, limestone rock and compost. Drainage is facilitated through the perforated pipes.

ii) Disturbance supports the recovery of an ecosystem. E.g., lake and mine land restoration.

iii)    Microorganisms can be engineered in laboratories so as to harness their potential for the degradation of chlorinated hydrocarbons.

iv)    Volatile organic compounds can be removed from aquifers by pumping and aeration of ground water.

The practice of ecological restoration refers particularly focuses on maintaining the balance between ecological integrity and human well-being. Some terms like ecosystem degradation and restoration, remediation, reclamation, rehabilitation, and reference ecosystem are most commonly used while describing the process of ecological restoration.

5. Strategies of restoration

Depending upon the extent of degradation, three basic strategies are used for ecological restoration.

5.1 Natural recovery or passive restoration: This strategy of restoration can be explained by some examples.

i) In wetlands, cattle grazing can harm the wetlands. Here, Passive restoration strategy can be applied that involves the cattle removal. This will allow the restoration of wetland hydrology, re-colonization and regeneration of animals and plants. This approach is appropriate if the basic characteristics of the degraded wetland are retained.

ii) If we compare the application of passive restoration on aquatic and land ecosystem, then the population establishment rate or natural succession will be rapid for the former and slow for the latter.

5.2 Active or full restoration: The aim is to recreate those conditions of an ecosystem that were present before the disturbance. This process is expensive and time consuming.

Ecosystem restoration via this strategy faces several difficulties like

i)  Insufficient information about the original system

ii)  Some factors that are responsible for damage cannot be halted e.g., acid rain

6. Central concerns in ecological restoration:

Some basic concerns that are associated with restoration projects are:

a)      Cost and benefits

b)      Product quality

c)      Feasibility and authenticity

a)   Cost and benefits: Restoration cost places a price on the ecosystem. The restoration cost depends upon the scale of restoration project, objectives of the project, and land use options.

b)  Product: In a degraded ecosystem, structure and function are two components that need to be restored.

i)  Habitat restoration: It is believed that if the substrate, hydrology etc. within a habitat is restored, and then the flora and fauna of the particular communities will be restored automatically. Therefore, habitat restoration is the first step in every restoration programme.

ii) Species/community restoration: Those plant and animal species/ communities are reintroduced that had declined or will decline in future. Example, seeding of a degraded pasture or planting of a degraded forest. Natural process of colonization and dispersal is a successful technique for the reintroduction of wide variety of species in comparison to traditional seeding methods.

iii) Quality restoration: quality of the restored ecosystem should be retained. E.g., enrichment of biodiversity, and removal of the contaminants from the soil.

iv)Ecosystem restoration: It is possible that the ecological functions can be restored completely. However, the attainment of ecosystem’s original structure is difficult. For example, biological functions of soil can be restored within ten years. However, it will take approximately 500 years to achieve original structure.

c)   Feasibility and authenticity: Restoration feasibility differs for different ecosystems and also depends upon the extent of degradation. Authenticity addresses its aesthetic and historical value.

7.  Terrestrial Ecosystem Restoration

a)   Habitat restoration: A vanished ecosystem was restored by digging ponds and replanting forests. It provided habitat to endangered Bermuda Cahow.

b)  Restoration of Curtis Prairie: Native grasses and annual plants were planted manually at the University of Wisconsin, Arboretum. The restored ecosystem ultimately became Curtis Prairie of University of Wisconsin. The restoration of prairie ecosystem was necessary in mid west United States since it was the most threatened ecosystem.

c)   Restoration of surface mined lands: Planting of Albizzia lebbeck and Albizzia procera led to the restoration of mine spoils of Singrauli coal field in Madhya Pradesh. However, the restoration potential was greater for A. lebbeck.

d)  Restoration of longleaf pine forest landscape: Once there was a time when longleaf pine forests stretched from North Carolina to Texas, covering an area of 60%. But, these forests now cover only 10% area. Restoration of longleaf pine forests presents a good example of ecological restoration. Fires were reintroduced and populations of indigenous plants and animals were established for the restoration of this precious ecosystem.

e)   Restoration of dry tropical forest: Dry tropical forests in Central America are the most threatened ecosystems. Several unique animal and plant species have also become rare due to the loss of forest cover. Scientists are trying to restore nearly 700 km2 of dry tropical forest to its original state.

8.  Restoration of aquatic ecosystem

Aquatic ecosystems like rivers, wetlands, streams and lakes, benefit the human beings. In addition to the transport of nutrients, water and sediments from land to sea, rivers also regulate the fertility and salinity of estuaries. Deltas and beaches are built by rivers. Wetlands provide habitat for wildlife species and fishes. However, anthropogenic activities are producing negative impacts on aquatic ecosystems. These negative effects have to be reduced so that the original state of ecosystem is maintained.

a)  Process of lake restoration: The following strategies are used for the restoration of degraded lake ecosystem.

i)        Toxic substances are neutralized.

ii)      Dredging of sediments

iii)    Discharge route of industrial waste water and sewage is diverted.

iv)    pH is regulated

v)      Hypolimnion is artificially aerated through air bubbling.

vi)    Water levels are raised in lakes where it has been lowered.

b)     Restoration of lake Trummen: Lake Trummen was an oligotrophic lake. Wastewater from industries and sewage polluted it and turned it into a humic lake. Soft bottom sediments were removed by suction dredging.

c)   Restoration of lake Chilika: Chilika lake of Orissa is a natural fresh and brackish water ecosystem and designated as Ramsar site. It provides good example of coordination between local people and government agencies. This lake provides habitat to migratory and native birds, and fish species including Irrawady dolphin and sea cow. Chilika lagoon was facing anthropogenic and ecological pressure it led to the loss of biodiversity, productivity and also affected the livelihood of local people. Constant inflow of 13 milliontons of silt per year was choking the mouth of Chilika Lake. Silted area was reported to be infested with grasses and weeds. Salinity was restored by dredging an artificial mouth so as to reduce the length of inlet channel by 18 km. Opening of artificial mouth showed an improvement in water exchange and facilitated the free migration of fish.

9.  Ecosystem degradation and restoration

The origins of ecosystem degradation

All organisms present on the earth planet do not possess same capacity for altering their environment. Some organisms affect the activities of other components of the ecosystem in a well suited manner. This capacity of organisms to alter the ecosystem is termed as ecosystem engineering. The intensity of environmental alteration directly depends on the period of the activity, the density of population, and other factors. Human activities involving the use of large amount of energy permit environmental alterations on large-scale with several major consequences including environmental degradation.

Thresholds of ecosystem degradation

The process of degradation is not a linear one. It may proceed in discrete steps (thresholds or transition boundaries). For terrestrial ecosystems, threshold steps are associated with the loss of vegetation cover. Classical models of competition suggest that 30-40% of vegetation cover must be present to avoid those processes that are promoting self-degradation processes. Ecosystem includes some structural (plant cover, species richness, and keystone species), and functional attributes (soil organic matter content, rainfall efficiency productivity). Some steps in the degradation process are not of equal magnitude or importance. There are some steps that can hardly be reversed and thus are called thresholds of irreversibility or transition boundaries. These steps require external energy inputs in the form of restoration techniques. Thresholds of irreversibility may be related to the elimination of particular functional groups or species.

10. Case studies related to restoration ecology in India

a) Ecological Restoration of Lantana-Invaded. Landscapes in Corbett Tiger Reserve:

Tropical and subtropical belts in India enclose some protected areas that have been invaded by some destructive weeds. Corbett National Park is also a protected area and was declared first national park in 1936. However, the management of this park has become a major challenge due to invasion by Lantana camara. Lantana known by scientific name Lantana camara has been placed in the category of the most destructive weeds present globally. Babu et al., 2009 made an attempt to resolve the problem of Lantana in Corbett Tiger reserve. They developed three step approaches.

i)        First objective was to develop control measures after understanding the biology of Lantana.

ii)      Second objective was to frame simple and cost-effective control measures.

iii)    Third objective was to develop a suitable restoration program, keeping in view the necessities of the reference ecosystems and stakeholders.

On the basis of the studies of ecology and seed biology of Lantana, Babu et al. developed a simple and cheap physical method for the eradication of Lantana. The method was named as Cut Root Stock method (CRS). In this method, a cut is made below the transition zone of root-stem. This transition zone was selected since it is an active proliferation site for Lantana. However, Lantana removal by CRS method was not enough since the land left after weed removal was prone to secondary invasion by other weeds like Senna tora, S. occidentalis and Lantana itself. Therefore, it became necessary to develop suitable restoration program for weed free areas also. Considering the above discussed facts, Babu et al. developed a restoration technique that consisted of four steps.

i) To identify reference ecosystems in undisturbed areas of parks.

ii) To identify the target conditions and requirements of stake holders.

iii)To develop field nurseries and introduce selected species sequentially into Lantana-free areas.

iv)The last step was the most important and involved monitoring and observing certain activities like manual weeding along drainage channels and under perching trees such as Crateva religiosa, Gardenia turgid etc.

Results: After two years of restoration program (2005-2007) at Corbett tiger reserve, the selected plots exhibited the dominance of grassland communities and legumes.

b) Restoration of Lake Kukkarahalli in Mysore, India:

Important points and features of Lake Kukkarahalli

• Manmade lake constructed in 1881 for the adequate supply of drinking water.
• Spread over an area of 104 hectares.
• Partly aquatic habitat and partly arboretum and supports flora and fauna.
• Supports birds, crocodiles, diatoms, algae, desmids, euglenoids, fishes and dinoflagellates.

Lake kukkarahalli suffered several ecological problems like

• Untreated sewage from Jayalakshmipuram, Padavarahalli, Ontikoppal and Mysore University entered into the lake. As a result, catchment area was reduced.
• Solid wastes were dumped indiscriminately.
• Lake resources were utilized in non-desirable manner for aquaculture and medicinal plants.
• Feeder canal area reduced form 25 km to 5 km due to urbanization.
• Siltation and presence of algal blooms reduced the water level.
• Wildlife and biomass were not managed properly.
• Water quality was not monitored.
• Open defecation was also a problem.

Kukkarahalli Lake in 2001

Toxic blooms of Microcystis aeruginosa occurred in the lake and led to eutrophication. Eutrophication led to the depletion of water quality and an increase in BOD level. This led to the mortality of fishes. Moreover, people living in the surrounding areas of lake suffered from cough, fever etc. Therefore, restoration of lake was started in 2003 by the grant (91 lakh) received from Asian Development Bank.

Methods for lake restoration

•  Inflow of sewage was blocked.
• Dumping of waste material including biomedical wastes was inhibited.
• Algal blooms were removed manually.

• 4. Weeds present at the periphery of the lake were removed.
• 5. Engineering techniques were used to clean the lake boundary.
• Immersion of Lord Ganesha idols was stopped
• Security system mainly for bird killing was increased.
• Water was aerated by peddling, boating-rowing by NCC cadets.
• Water quality was improved by the inflow of filter cleaned water. This work was started at Vanivilas Water works, Mysore City Corporation.
• Saplings of trees like jambolana, neem etc. were planted.
• Parks were formed for the purpose of recreation.
• Awareness was created among the local people for the protection and conservation of the lake.

c)  Mangrove restoration: a case study from India

Mangrove forests represent an essential part of coastal ecosystems and also play an important role in climate change mitigation. Mangrove forests grow mainly in estuaries and marine shorelines and their roots expand deep into the coastal sediment. They prevent unnecessary sedimentation and act as natural barriers to floods and rising sea levels. Mangroves are cleared mainly for agriculture, housing, and fuel wood. The integrity of the coastal ecology is getting devastated due to the deposition of untreated sewage and industrial wastes. In Andhra Pradesh, India, mangrove restoration has become the primary aim to re-establish the coastal ecology. Villagers maintain the growth of mangrove trees by digging canals so as to direct the water current through mangrove forests, and thereby, contribute to the geography and hydrology restoration of the coastal ecosystem.

d)   Land reclamation and restoration of natural ecosystem: a case study from opencast mines of north eastern Coalfields of India.

Opencast mining (OCM) in North eastern coalfields (NEC) of Assam disrupted ecology of that particular region and gave rise to the problem of land degradation. Ecological succession set up over thousands of years was badly affected on hilltops where OCM was carried out. OCM also disturbed wildlife, destructed large paddy fields due to the deposition of silt, and blocked spring and river waters. All these destructive events affected local population. Local people protested to NEC authorities and Government of India about the ecological imbalance and environmental degradation caused by OCM. Sincere efforts were made by NEC authorities for land reclamation and restoration of vegetation. Greater attention was paid towards slope stability in those areas where landslides were more prevalent. Only those species were selected for plantations that were having good soil binding properties to arrest soil wash off and soil erosion. To prevent mechanical damage to plants raised in overburden dumping areas, structures in the form of stone barriers, check dams, terraces and bamboo barricades, and gully plugging measures were taken to prevent soil erosion and ensure stability of slopes. Moreover, the denuded areas were recovered with green mass of vegetation. Species planted on denuded and mined areas included Lactuca serriola, Mesua ferrea, Dalbergia sissoo, Terminalia arjuna, Delonix regia, Tinospora cordifelia, Albizzia lebbeck, Cedrella toona etc. All these efforts led to the partial restoration of the ecosystem to its original state.

Conclusion

This chapter provides the brief knowledge about restoration ecology. Restoration ecology has been defined along with its all aspects, approaches and strategies. Case studies in India have been mentioned along with the necessary measures taken for restoration of the degraded ecosystems. Ecosystem Restoration involves

• The assessment of type, degree, extent and location of degraded ecosystems.
• Identification of those geographical areas where restoration will prove beneficial to achieve national level biodiversity targets.
• Local people and relevant stakeholders should be involved.
• Multiple benefits and potential costs of ecosystem restoration should be assessed at relevant scales.
• Legal, institutional and policy frameworks should be assessed.