25 Green Belt Development

Sunil Mittal

Module 25: Green Belt development

1. Introduction

2. History of Green Belt

3. Particular Species used in Green Belt

4. Criticism

5. Case Study

5.1 Challenge

5.2 Solution achieved

5.3 Results

6. The Green Belt debate

7. Guidelines, Regulations and Future Challenges for Green Belt Development

7.1 Plant pollutant interaction

7.2  Theoretical model for green belt development

7.3  Selection of plants for green belt development

7.4  Stabilization of fly-ash with plants

8. Precautions

9. Future challenges for Green Belt land

1.   Introduction

Green belt is a policy which is used in land use planning to retain areas of undeveloped, wild, or agricultural land surrounding or neighbouring urban areas.

Or

A green belt is an invisible line designating a border around a certain area, preventing development of the area and allowing wildlife to return and be established.

Purpose of Green Belt

• The stated objectives of green belt policy are to:
• Protection of natural or semi-natural environments Improvement of air quality in urban parts
• Confirm that urban inhabitants have admittance to landscape, with consequent informative and recreational opportunities
• Protection of rural societies that might otherwise be absorbed by expanding cities.

Advantages of Green Belt

i. Air Pollution control: Trees removes carbon dioxide from the environment through the process of photosynthesis and release of oxygen. This way they help to remove pollutants from air and improve air quality. A green belt development would trap particulate matter and help in their removal from the air.

ii.  Noise control: A green belt works as a barrier to the high intensity sound waves. The sound waves can be deflected, refracted or absorbed by the trees that ultimately reduce their intensity. Extend of intensity reduction depends on the distance of green belt from the source of sound waves. Trees can make impact on humidity and climate which affects sound intensity.

iii. The root system of trees binds to soil particles and helps in soil erosion control by improving soil quality.

iv. Green belt retains water and prevent water run offs.

v. Green belt offers area for walking, camping, and biking close to the cities and towns.

vi. Green belt provide habitat  for plants, animals and wildlife.

vii. Green belt provides better land use of patterns around the cities.

The efficiency of green belts varies depending on the location and country. They can often be degraded by misuse by the urban dwellers. Sometimes infrastructural development compromises with the green belt area. This results in the reduction of green belts and creation of satellite towns.

2.   History of Green Belt

The concept of Green Belt was initially suggested in the late 19th century. In 1898, Ebenezer Howard proposed an idea of Garden Cities. These garden cities were intended to be planned and self-contained communities surrounded by greenbelts. These green belts contain carefully balanced areas of residences, industry, and agriculture. In the 1930s, Campaign to Protect Rural England (CPRE) campaigned for a clear barrier of undeveloped land against ribbon development and urban sprawl. As a result of these campaigns and other local initiatives, the first Green Belts were designated in London and Sheffield. By 1955, Green Belts were firmly supported by both national planning legislation and policy. CPRE has continued to be involved in campaigning for Green Belt designation, and permanent protection.

Key dates in Green Belt History

Other historical prospects include:

1. Proposal for green belt development around the Levite towns in the Land of Israel was outlined by Old Testament.
2. Moses Maimonides expounded that the greenbelt plan from the Old Testament referred to all towns in ancient Israel.
3. In the 7th century, Muhammad established a green belt around Medina. He did this by prohibiting any further removal of trees in a 12-mile long strip around the city.
4. In 1580 Elizabeth I of England banned new building in a 3-mile wide belt around the City of London in an attempt to stop the spread of plague.
5. United Kingdom pioneered in the Green belt policy. Since 1890 onwards, various proposals were discussed but the first to gather extensive support was proposed n 1919 by the London Society in its “Development Plan of Greater London”. They proposed continuous belt (of up to two miles wide) alongside the CPRE to prevent urban sprawl, beyond which new development could occur.
6. In recent aspect of sustainable development where development has to be done in harmony with environment safety, the concept of green belt is not only green space but also green structure. All developed and developing nations such as European countries are taking up “Case studies in Green Structure Planning” and creating new green area in the vicinity and/or premises of governmental constructions.

3.    Particular species used in Green belt

1. Plants which counteract odour are:

a)    Bushes with slight but lively fragrance.

b) Acacia farnesiana (Mexican plant): It is plant with yellow colored flowers with fragrance. These plants do not have rich cover but have counteracting smell. But, they have limitation of seasonality and thorny nature.

c)    Melaleuca species: The members of this species have sweet fragrance and thin cover in India.

d)  Pine, Cedar, Junipers: They provide protection and rich canopy but, are site specific.

e)   Eucalyptus: They provide wide cover and can be used for their specific odour. But, they also suffer with the limitations of site specificity and height in the urban neighborhood.

f)    Hedges, Herbs (Tulsi, Turmeric etc.) can also be used for their effective odour.

g)   Vetiver: This plant is renowned as king of perfumes due to its strong odour which can inactivate other odours. It’s odour relieves fatigue and affects the nervous system, due to which it is used as a key specie in aromatherapy.

h) Plants which tolerate pollution – A plant which has high efficiency in pollution tolerance is Nerium (Kaner).

i)     Other than these plants species used for green belt are Neem, Acacia auriculiformis, Pongamia pinnata, Bamboo, and Casuarina etc.

Development within Green Belts is strictly controlled and there is a general presumption against inappropriate development. Appropriate Green Belt development includes some mineral extraction, small-scale infill development within villages, the extension of existing buildings and development strictly required in connection with agriculture, forestry and outdoor sport and recreation.

4.   Criticism

a)   Housing crisis

Although, green belt has huge benefits (public health, environment), but these benefits do not ensure as claimed. Only a small fraction of the population uses green belt for leisure purposes. It is claimed that green belt is not playing any significant role in making air and water clean. Rather, the decision of the green-belt development is to prevent housing demand within the zone.

b)  Increasing urban sprawl

The population explosion has led to extension of urban communities to less dense areas. Examples include Ottawa suburbs of Kanata and Orleans. Both of these are outside the city’s greenbelt, and are currently undergoing explosive growth. This leads to other problems such as residents of these areas have a longer travel to work places in the city and worse access to public transport. It means people travel through the green belt. However, this area is not designed to cope with high levels of transportation.

5. Case Study: ENVI helps The Green Belt Movement analyze vital Kenyan ecosystem 5.1 Challenge

The Aberdare’s Forest is the source of drinking water for millions of Kenyans. However deforestation and destruction of the watersheds negatively impacted these vital water resources. To solve this problem, the Green Belt Movement (GBM) came up with a plan to plant two million indigenous trees on 2,000 hectares of degraded forestland in Aberdare’s to restore the water catchments. This initiative required GBM to first analyze the situation on the ground in order to determine the suitable mitigation measures.

5.2 Solution achieved

ENVI image analysis tools were used, in conjunction with ArcGIS to extract and fuse information from LANDSAT, GeoEye and IKONOS to determine the different land use classifications and habitats. In addition, ENVI’s interoperability with ArcGIS allowed the easy movement of land use and land cover information from geospatial imagery into ArcGIS for additional analysis.

Land cover change maps created in ENVI provided up-to-date, accurate information that helped project managers to determine:

• The potential watershed restoration activities that would support the protection and conservation of vital habitats in the Aberdare ecosystem.
• The approximate area that required immediate restoration.
• The resources that would be required to effectively restore the ecosystem.

Manually detection change by visually comparing images or analyzing images pixel by pixel can be labor intensive and time consuming. Moreover, it leads to mis-identifications and other inadvertent errors.

5.3 Results

Results generated in ENVI facilitated the successful implementation of the Restoration of Aberdare Ecosystem project.

Achievements of the Restoration of Aberdare Ecosystem Project are as:

• 1,700 hectares of degraded forest areas were rehabilitated by planting two million trees along rivers, water-catchment areas, and public land and on private farms.
• The rehabilitated areas show improved conditions and nearly 60 dried-up streams begun to flow again.
•  The project achieved targets at minimal cost.
• The community has earned over US$80,000 in revenue from selling tree seedlings.
• Monitoring of trees with GIS technology as well as close surveillance by youth ‘green rangers’ show significant tree growth and improved ground vegetation.
• The project has strengthened community forest associations, enabling them to co-manage forest areas with the Kenya Forest Service.

6.      The Green Belt debate

The debate over Green Belt policy tends to fall into two categories:

A.    Its effectiveness as a planning mechanism

• Does Green Belt support sustainability by encouraging urban regeneration and concentration of homes, services and employment opportunities or does it prevent sufficient homes being built.
• Are other tools such as strategic gaps and green wedges more effective at creating a sustainable urban form?
• Should there be more flexibility in terms of permitted development?

B.     Its role in environmental management

• Does the Green Belt designation impact on the management of land in the urban fringe?
• Have the land use objectives for Green Belt land encouraged positive land management?
• What are the best ways of preventing degradation of land in the urban fringe and maximizing productivity of the land, and the benefits to people?

7.Guidelines, Regulations and Future Challenges for Green Belt Development

Most of the human activities generate pollution of different types and magnitudes, to which all the organisms are exposed. Organisms tend to avoid or move away from pollution. By avoidance or by tolerance organisms struggle and survive in polluted environments.

However, such survival is hardly desirable and has limitations. Hence, it is imperative that pollution should be controlled at the source itself. Numerous mechanical devices are available for controlling pollution. However, some trace amount is still likely to get released. In such type of scenarios, Green belts are thought to be effective. Green plants form a surface capable of sorbing air pollutants.

An important aspect of a green belt is that the plants constituting green belts are living organisms. These plants have certain tolerance limits towards air pollutants. As a result crossing the threshold limits in terms of pollution load, would lead to injury of plants causing death of tissues and reducing their absorption potential. This will defeat the purpose of a green belt. In short, a green belt is effective as pollution sink only within the tolerance limits of constituent plants.

Two types of approaches are recognised while designing green belts

i) Source oriented approach

ii) Receptor- oriented approach.

Both these approaches have their own advantages and limitations. It is generally felt that the first approach is advantageous where a single industry is situated and the pollutants emitted by the same are sought to be contained. The latter approach is desirable in urban- industrial complexes with multiple sources of pollution in an industrial – urban mix.

Apart from functioning as pollutant sinks, green belts would provide other benefits like aesthetic improvement and providing possible habitats for birds and animals.

Guidelines For Green Belt Development Include:

1. Plant-Pollutant Interactions
2.   Theoretical models for green belt development
3. Selection of plants for green belt
4. Stabilization of fly-ash with plants

7.1 Plant-Pollutant Interactions:

Plants are living organisms and hence are prone to suffer toxicity of air pollutants like any other organism. Still, they are expected to scavenge pollutants from the ambient air. Major primary pollutants of industrial origin are considered here.

SO2: SO2 enters plants mainly through the stomatal apertures. Hence stomata their structure, position and functions are important in the entry of gas in a leaf. Once inside the leaf, it passes into the intercellular spaces of mesophyll and gets absorbed on the wet cell-walls to finally diffuse into the cell sap. Initial visual symptom of foliar 1njury caused by SO2 is the formation of marginal and interveinal chlorotic, bronzed or necrotic areas starting with dark green or dull colouration, with water-soaked appearance. Necrotic areas extend and are visible on both epidermal surfaces. Older leaves are the most susceptible ones since they have just attained full expansion.

NOx: Three types of oxides of nitrogen are collectively referred as NOx. These are Nitrous oxide), Nitric oxide and Nitrogen dioxide. Injury symptoms are visible as discoloured spots of gray-green or light brown colour, bleached or necrotic spots in interveinal areas of leaves. NOx are not considered to be of major concern as phyto-toxicants.

HF: Fluoride enters leaf through stomata and diffuses into vascular tissues from the intercellular spaces of mesophyll. Chlorosis of leaf tip is the first visible injury. Injured brown or dead areas of leaves become necrotic leading to premature leaf fall.

CO and CO2: These are not phytotoxic gases.

NH3: Ammonia injury symptoms include blackening and bleaching of leaves, spotting, brown lesions between veins and colour change of fruits.

H2S: Necrosis and death of young tissues is reported rather than that of old tissues.

The plants uptake air pollutants in the following order

HF>SO2>Cl>NO2>O3>PAN>NO>CO

The rate of pollutant removal is found to increase linearly as the concentration of the pollutant increased over the ranges of concentration that are encountered in ambient air and which are low enough not to cause stomata closure. Pollutants are absorbed most efficiently by plant foliage near the canopy surface where diffusion process is high due to favourable light conditions.

7.2 Theoretical Models for Green Belt Development

Interaction of pollution with vegetation has always been expressed by a common parameter known as the deposition velocity of the pollutants. The deposition velocity is defined as follows:

It has dimensions of Ms^-1.

Green belt development model incorporates following parameters for computation of pollution attenuation factor.

i. Physical characteristics of the green belt, e.g., distance from the source, width, height and leaf surface area density.

ii.  Aerodynamic properties e. g, wind speed through green belt and effective height of the incident air stream.

iii. Deposition velocity of the pollutant.

iv. Atmospheric stability conditions.

Application of Green belt Model

The green belt model is applied to different cases for studying the usefulness of green belt in reducing the impact of pollution. Out of the two applications, one is a source oriented approach and the other is receptor oriented approach. In the source oriented approach, green belt of suitable dimension is planted around a source emitting pollution and studies are made to know the usefulness of green belt in reducing the effects of pollution for ground level releases. In the receptor oriented approach, green belt of suitable dimension is planted around an object which is getting deteriorated or likely to get deteriorated as a result of pollution.

Source Oriented Approach

A nuclear power reactor surrounded by a suitably designed green belt provides an example of the source oriented approach.

Benefits of developing a suitably designed green belt around nuclear power plants are as follows:

i) The early and continued mortalities are practically eliminated beyond a distance of 3 km.

ii) The relocation of population to protect it from long term external exposure from ground contamination may not be required

iii) The supply of food from uncontaminated areas may be needed for populations living within 2 to 20 km only in the affected sector.

Receptor Oriented Approach

Mathematically both source and receptor oriented approach are the same, the only difference between the two is the manner in which the green belt is planted. In the source oriented approach, the green belt is planted around the pollution source, whereas in the receptor oriented approach the receptor is protected against pollution by planting a green belt around it. The case of protecting the Taj Mahal against air pollution by a green belt is an example of receptor oriented approach.

7.3 Selection of Plants for Green Belt

Characters of plants including shapes of crowns considered necessary for effecting absorption of pollutant gases and removal of dust particles are as follows:

For absorption of gases

i.  Tolerance towards pollutants that is not too high to be instantaneously lethal.

ii.  Longer duration of foliage.

iii.  Freely exposed foliage through:

a. Adequate height of crown

b. Openness of foliage in canopy

c. Big leaves (long and broad laminar surfaces)

d. Large number of stomatal apertures

e. Stomata well-exposed (in level with the general epidermal surface)

For removal of suspended particulate matter

i. Height and spread of crown

ii. Leaves supported on firm petioles

iii.   Abundance of surfaces on bark and foliage, through

a.  Roughness of bark,

b. Epidermal outgrowths on petioles.

c.  Abundance of axillary hairs,

d. Hairs or scales on laminar surfaces.

e. Stomata protected (by wax, arches/rings, hairs, etc)

All tolerant plants are not necessarily good for green belts. e.g., Xerophytes with sunken stomata can withstand pollution by avoidance but are poor absorbers of pollutants due to low gaseous exchange capacity.

Plantation along Roadsides

Components of green belts on roadsides should be both absorbers of gases as well as of dust particles including even lead particulates. Choice of plants for roadside plantations may be for containment of pollution and for formation of a screen between traffic and roads side residences. This choice of plants should include shrubs of height 1 to 1.5 m and tree of 3 to 5 m height. The intermixing of trees and shrubs should be such that the foliage area density in vertical is almost uniform.

7.4 Stabilization of Fly-Ash with Plants

Suggested procedure for Plantation

Fly ash is deficient in plant nutrients like nitrogen and sometimes phosphorus and other minerals and contains toxic metals like copper, cadmium, cobalt, chromium and manganese, molybdenum nickel, lead, zinc and boron. Amendment of ash with nutrients and agents to arrest toxicants are essential for covering it with plants. Some suitable and inexpensive soil additives are given in Table 1 along with their properties.

Table 1: Soil additives and their properties

Cultivation of grasses stabilizes the ash surface effectively. Grasses with high turnover rate of shoots contribute substantially to the organic enrichment of the otherwise nutrient-poor silty ash. Weathered ash is reported to be substantially less toxic than the freshly deposited ash. Some plants have been enlisted that are considered suitable for growing on ash dumps for their stabilization (Table 2). The plants listed are grasses, legumes and MPTs (multi-purpose trees) forming a comprehensive agroforestry system. Testing of edible parts of plants for toxic heavy metal contents would help decision-making for deriving agricultural yield from stabilized ash dumps.

Table 2: List of grasses, legumes and multi-purpose trees suggested for cultivation

for stabilization of Fly-Ash

Grasses

Bothriochloa intermedia

Brachiaria mutica

Chloris gayana

Cynodon dactylon

Echinochloa colona

Heteropogon contortus

Sehima nervosum

Herbaceous Legumes

Cajanus cajan

Medicago sativa

Phaseolus mungo

Desmodium triflorum

Trees

Acacia catechu

Acacia nilotica

Albizia lebbeck

Albizia amara

Azadirachta indica

8.   Precautions

There are several variables in the environment leading to pollution stress. Major variation is in the set of bio-geographical conditions – especially climate and topography. As a result of which corresponding modifications in planting strategies become necessary. A large variety of local (climatically adapted) plant species need to be tried. In case of failure of any of the species to respond as expected, a thorough investigation into the causes of failures is called for. Such investigations provide guidelines for corrective measures and modifications in plans.

Continuous monitoring of plant growth, immediate replacement of casualties, supplementation of nutrients, rescheduling of watering regimes, etc. are important.

9. Future Challenges for Green Belt Land New challenges, new expectations

The land around our towns and cities is continually facing a range of challenges and conflicting land use priorities. Green Belt policy has provided a framework for making some decisions around the towns and cities. It is a simple framework that assumes that urban areas need open space and breathing spaces around them. If not, urban development would sprawl and settlements would become too big and lose their historic character. The green belt policy has defended against this successfully. But there are new challenges in the 21st century, and new expectations. It is recognized that people benefit from having access to green spaces within a short distance from where they live. Quality places they can visit without driving or a long journey by public transport to get there will be in greater demand. Outdoor spaces that not only provide opportunities for exercise, relaxation or social activity, but which also provide a broad range of environmental benefits and ecosystem services. To tackle these challenges and expectations on finite area of land a multi-functional approach, combining different land uses in the same space, is required to plan and manage Green Belt.

Summary

In this chapter, the writers produced general information on the green belt development, its effects on environment and advantages. Some particular plant species used in green belt mentioned were also mentioned along with their features. Commonly employed methods for green belt development were also summarized. Historical aspects of green belt were also discussed in brief. In short, one can say that green belt development has received appreciation as well as criticism.

References

1. http://apspcb.org.in/images/pdf/ch6_greenbelt_development.pdf
2. http://londonfirst.co.uk/wp-content/uploads/2015/02/Green-Belt-Report-February-2015.pdf
3. http://www.ruaf.org/ruaf_bieb/upload/3284.pdf
4. http://cpcbenvis.nic.in/scanned%20reports/PROBES75%20Guidelines%20For%20Developing%20Greenbelts.pdf
5. https://www.legco.gov.hk/general/english/library/stay_informed_overseas_policy_up dates/green_belt.pdf
6. http://www.woking2027.info/ldfresearch/greenbeltreview/gbbrbrief.pdf