IN PUNJAB, IT’S TIME TO FOCUS ON URBAN FORESTRY

FOREST ISLANDS COOL DOWN OVERHEATED CONCRETE JUNGLES

As you go over the fly over of Kharar on National Highway 05 you will see a concrete jungle as far as you can see but very little greenery. After independence many cities like this which expanded are an aggregate of illegal colonies developed by unscrupulous developers and builders (who were hand and glove with corrupt officials and politicians) later made legal had unplanned layouts and expanded on a very large scale. So developing a picture of these cities in sub parts  one can say  that most cities in Punjab  are consisting of old congested city portion with little green spaces barring few like Patiala, illegal turned legal colonies with narrow roads and little green space, planned government planned spaces fast turning into commercial spaces under political patronage and planned private developed high rise and cities planned with green spaces But majority of the cities, towns and small towns are a mixture of planned and unplanned growth towns minus any thought for green spaces but devoted to utilise every square foot of developed space leading to concrete jungles.

So we now want to reverse this unplanned ugly growth minus greenery by introducing green spaces in horizontal mode like tree belts/ parks, vertical mode by vertical gardens where we lack horizontal space and rooftops where we can do wonders with kitchen gardens and medium bush tree garden concept. How all this will be achieved, here comes into play the concept of urban forestry which is the art and science of managing trees and forest resources in and around urban community ecosystems for availing physiological, sociological, economic and aesthetic benefits trees provide for society.

Another factor which Is pushing us to consider urban forestry urgently is the ongoing climate change where we are having overheated ac cooled concrete jungles which are not producing enough evapotranspiration as they lack greenery of all types.

Urban Forestry concentrates on all tree-dominated as well as other green resources in and around urban areas, such as woodlands, public and private urban parks and gardens, street tree and square plantations, botanical gardens and cemeteries.

Gandhinagar leads in per capita urban greenery among Indian cities with Chandigarh taking second. Cities renowned for their urban green spaces often have 20% to 35% coverage of total geographical area. For Chandigarh it is 35%, Delhi 20% and Gandhinagar it is 57.13%.

WHY URBAN-FORESTRY IS NEEDED?

The urban population growth of 31.8 % during 2001–2011 is far ahead of simultaneous national population growth of 17.6 %. Cities are already facing multiple problems and about 40% of the population will be residing in urban areas by 2030 which will further aggravate urban problems. Some problems associated with lack of urban greenery are:

 • Increased Carbon Emissions: Cities occupy less than 3% of the global terrestrial surface but accounts for 78% of the carbon emissions.

 • Climate change Induced Heat Waves and Dust storms: Heat waves aggravate thermal discomfort and culminate in health issues.

 • Creation of ‘Micro-Climates’ and Urban Heat Islands (UHI): Reduced potential for evaporative cooling increases the net heat stored in urban environments and leads to UHIs, thus developing a peculiar ‘micro climate’ in and around urban landscape.

 • Decreasing Biodiversity: Depletion of green cover has caused habitat loss and shrinking shelter for various fauna.

 • Reduced Ecosystem Services: Forests provide a variety of ecosystem services which are lost due to absence of green cover in and around cities.

 • Check Unsustainable Development: Unplanned, explosive and pressurized development has resulted in loss of essential ecology and its components including wetlands, absence of which reduces natural mitigation of disasters. E.g. Chennai Floods.

BENEFITS

ENGINEERING AND ECOLOGICAL BENEFITS

 Urban forestry plays an important role in addressing environmental engineering problems, including those related to erosion control, noise and air pollution abatement, wastewater management, watershed protection, and glare, reflection, and traffic control etc.

URBAN FORESTRY ENSURES SOIL EROSION CONTROL

 Although erosion control and watershed protection are important issues in rural areas, they are also a major concern in urban centres. Urban vegetation (trees and other plants) can be used to mitigate extreme stormwater runoff events in urban areas, and in many cases this role can justify the attention placed on the development and maintenance of urban forests (Sanders 1986). Urban trees can affect stream flows as well, by their ability to intercept rainfall and affect soil infiltration rates of water. These acts can reduce surface water runoff, which can indirectly affect water quality by reducing the amount of sediment and urban pollutants entering a river system .Soil Erosion, however, can be caused by both wind and water, although wind has less of an effect than water does. Water-caused erosion is a particular concern in areas  where bare soil is exposed to precipitation. Soil loss due to precipitation runoff can occur when rills (narrow incisions into the upper portion of a soil surface) or gullies (ditches resulting from significant erosion of a soil surface) are formed on the ground, when upper layers of soil are washed away in a large sheet, or when soil is lost in a mass, downhill movement known as a mudslide or landslide. Landslides triggered by precipitation events are a perpetual problem in many coastal areas of both developed and developing countries . Some methods for improving the hydrology of urban areas include perforating compacted areas to improve water absorption and infiltration, planting trees and shrubs to bind the soil, implementing terracing practices and contour planting, and applying mulch to construction sites.

URBAN FORESTRY HELPS IN WASTEWATER MANAGEMENT

An important engineering issue that could be addressed by urban forests involves wastewater management . As the world population increases, the need to dispose of the daily wastewater produced will also increase, and urban forests have been used to absorb some of this. Several countries, including Egypt, Kuwait, Peru, and Yemen, use wastewater in their urban forests . Many countries around the world, including the United States, use this type of process for irrigating agricultural crops, yet water supply and drainage systems are not perfect, thus the overland flow of wastewater can find its way into forested areas within and outside urban areas . The effects are mixed, since nutrient levels can be limited in some forested ecosystems so adding nutrients to the system can potentially boost productivity; however, soils may retain heavy metals and high levels of phosphorus as a result.

URBAN FORESTS WORK AS NOISE ABATEMENT FIXTURES

Another possible engineering use of an urban forest is for noise abatement purposes . In general, taller trees and wider tree groups are most effective in reducing  pollution . Noise pollution Is composed of sounds, and sounds can be absorbed, deflected, reflected, or refracted. Reflected sounds bounce off objects, whereas absorbed sounds are trapped by objects. Refracted sounds are broken up and dissipated into the atmosphere, and deflected sounds bounce off objects and can be directed toward an area of least concern . Noise abatement is often necessary in areas where excessive noise occurs, such as along roadways. Given the high density of people living in urban areas and their associated transportation systems, noise often becomes a significant problem for local residents. Noise can be composed of different wavelengths of energy, and the manner in which it travels through the environment can be affected by a number of factors. For instance, the level of outdoor noise is a function of the source, the terrain, the surrounding vegetation, and atmospheric conditions such as wind speed and air temperature. Typically, as noise emanates from a source it decreases in intensity the further away it travels. In other words, noise is loudest the closer one is to it. As noise travels, it spreads in a spherical pattern across the landscape away from its point of origin. Interestingly, urban forests that are closer than about eight average tree heights from a noise can reduce noise pollution more effectively than trees situated further away.

Plant arrangement and density can moderate noise levels, and combining plants with different noise attenuation characteristics can more effectively reduce unwanted sounds . Noise heard upwind may be reduced by 25–30 decibels compared to noise downwind . This effect occurs because noise is directed upward toward the atmosphere when it travels upwind and is directed downward to the ground when it travels downwind.

URBAN FORESTS REDUCE AIR POLLUTION

Urban forests contribute to reductions in air pollution and improvements in air quality . Trees found in urban settings play very important roles in cleansing pollutants from the air. Whether trees are located in rows along a street, in parks, or in undeveloped areas, their leaves, branches, twigs, and boles can trap air pollutants. Typically, these trapped pollutants are washed into the ground during rainfall. Grey and Deneke (1978) refer to this process as air-washing. In addition, when trees are flowering, their floral scents mask disagreeable odours. Tree and shrub vegetative surfaces, therefore, play an important role in the interception of particulate matter pollution. The level of interception typically depends on particle shape and density, and the tree species employed. Plant vegetation can take up trace metal particles, such as lead, as well as radioactive particles, such as caesium isotopes . Trees, such as cottonwoods  have been used for arsenic and trichloroethylene uptake from the soil.

FACILITATE CARBON SEQUESTERING OR SINKING

Urban forests can also be used to facilitate carbon sink or sequestering  efforts. Carbon sequestration occurs when trees accumulate carbon and release oxygen (O2) essential for life. The conversion of forests to land uses such as roads, homes, office buildings, factories, shopping centres, sports stadiums, and airports releases carbon dioxide into the atmosphere, which contributes to climate change. Urban tree planting efforts, whether through green belts, parks, windbreaks, or shade trees around residential houses, can play an important role in the sequestration of carbon. One example is the nearly 55,000 tons of carbon that is expected to be sequestered through an urban tree program in Pretoria (Tshwane) South Africa . The development and maintenance of urban forests, coupled with sustainable living concepts such as recycling and wind, solar, and other renewable energy technologies, can be used to address the growing concern of global climate change. Interestingly, in one analysis a park-like design of an urban forest seemed to be less effective for carbon sequestration purposes than a forest-like design due to emissions from construction and maintenance activities.

FILTER OR BLOCKING GLARE AND REFLECTED LIGHT

Another engineering use of urban forests can involve their ability to filter or block glare and reflected light (Beatty and Heckman 1981, Smardon 1988). Materials such as light-coloured concrete, glass, water, snow, and metals can reflect light in ways that cause difficulties involving increased heat and concentrated light energy. The strategic placement of trees can mitigate some of these problems. In addition to reducing glare imposed on homes, urban trees can reduce glare imposed on automobile drivers and pedestrians, which increases human health and safety conditions.

MITIGATE URBAN HEAT ISLAND EFFECT

Microclimate and Urban Heat Island effect: Urban trees can help to improve the air quality by cooling and cleaning the air, reducing smog, ground-level ozone and greenhouse effect. They can mitigate the heat island effect by giving green lungs to cities

A variety of measures can be taken to mitigate the heat island effect in urban areas, including the application of cool roofs, cool pavements, green roofs, and urban forestry. Cool roofs are composed of materials that have a high albedo and therefore high reflectivity. Many cool roof materials also have a high emittance, which refers to the ability of a material to release thermal radiation. Cool roofs can significantly reduce roof temperatures and therefore reduce heat transfer into a building. More specifically, the U.S. EPA (http://www.epa. Gov/heat island) reports that summertime temperatures on a traditional roof may reach as high as 190 °F (88°C). Cool roofs, by comparison, will only reach 120°F (49°C). Cool pavements are generally composed of light-coloured material with a high permeability. Lighter colored pavements reflect more light and absorb less heat. Pavements with a high permeability allow water to percolate and evaporate, thereby cooling the pavement and surrounding air. Green roofs are roofs that have been planted with vegetation to reduce rooftop temperature and cool the surrounding air. A green roof consists of a waterproof membrane, a drainage system, a growing medium, and plants.

BENEFITS OF GREEN ROOFS

1. Reduce roof top temperatures.

2. Reduce temperature of surrounding air.

3. Reduce rainwater runoff to sewer systems.

4. Work as filtration systems for pollutants such as heavy metals and excess nutrients.

5. Provide habitat for birds and other small animals.

6. Esthetic green space for building residents.

Urban forestry is the process of incorporating vegetation into an urban area to increase cooling through shading and evapotranspiration. The United States Department of Agriculture Forest Service has reported that urban forestry can decrease midday maximum air temperatures by 0.07°F (0.04°C) to 0.36°F (0.2°C) for every 1% increase in canopy cover. Similarly, the incorporation of urban agriculture can also help reduce the heat island effect.

Phytoremediation of Air Pollutants by Planning and Selection of Plants to Improve Outdoor Air Quality.

As air pollution has become a major threat, afforestation policies to increase urban forestry would be a good investment. In an experiment, Nowak et al. (2014) reported that plants removed almost 17 million metric tonnes of air pollutants (like NO, NO2, and CO2) in the United States in 2010, accounting for almost US$ 6.8 billion. Parks and plant barriers have also been proven to be extremely effective at improving ambient environments. For phytoremediation, plants should possess these characteristics: have a large leaf area and rough stem; be ecologically compatible and indigenous in nature; require low water and agricultural input; have a high rate of pollutant absorption; be tolerant to the synergistic effects of pollutants; have climatic suitability; be tall and straight with a spreading canopy and medium growth rate; have aesthetic values like foliage and conspicuous, attractive flowers; and should be easily multiplied. Leaf morphology plays an important role in phytoremediation as leaf surface rigidity, or roughness, affects the deposition of particles. Stickier leaves are better for efficient dust capture than other types. Furthermore, evergreen trees are better filters than deciduous trees and leaves with complex shapes and large surface areas collect airborne particles more efficiently than other types. Having an abundant waxy layer on the needles and being evergreen, conifer plants are considered to be excellent pollutant accumulators throughout the year.

In Mumbai, Shetye and Chaphekar (1989) conducted a survey on dust fall in relation to common roadside trees and reported that mango trees (M. indica), pongamia (Derris indica), and umbrella trees (Thespepsia populnea) trapped considerable amounts of dust. Pokhriyal and Subba Rao (1986) found trees like neem (Azadirachta indica), gulmohar (Delonix regia), silk cotton (Bombax ceiba), pipal (Ficus religiosa), Indian laburnum (Cassia fistula and Cassia siamea), Indian lilac (Lagerstroemia indica), pagoda tree (Plumeria rubra and Plumeria alba), and java plum (Syzygium cumini) to be more suitable for urban environments. Among them Taxus sp. (yew) is found to be extremely tolerant against airborne particulates. Tamarind (Tamarindus indica) has smaller compound leaves and is more efficient in trapping dust compared to trees with larger leaves. Popek et al. (2013) found that particulate matter accumulation by trees and shrubs can be varied by more than 10-fold. Tree species like Pinus sylvestris, Alnus spaethii, Fraxinus excelsior, Pyrus calleryana, Populus sp., Robinia pseudoacacia, Sophora japonica, Ligustrum lucidum, and Quercus ilex, etc., are reported to have potential for the phytoremediation of airborne particulates. Similarly, some shrubs like Pinus mugo; Spiraea sp., Stephanandra incisa, Taxus baccata, Taxus media, Acer campestre, Hydrangea arborescens; Sorbaria sorbifolia; and Forsythia × intermedia are observed as excellent phytoremediators (Wang et al., 2015). Climbers like Parthenocissus tricuspidata, Parthenocissus quinquefolia, Hedera helix, and Polygonum aubertii could be efficient for the phytoremediation of particulates in dense habitats where the surface for growing plants is limited (Borowski et al., 2009). Herbaceous plants, such as Achillea millefolium, Polygonum aviculare, Berteroa incana, Flaveria trinervia, and Aster gymnocephalus can also be successful regarding phytoremediation (Weber et al., 2014). Takahashi et al. (2005) recommended four species among 70 species of woody plants, viz., R. pseudoacacia, Sophora japonica, Populus nigra, and Prunus lannesiana to plant in the vicinity of roads experiencing heavy traffic for air phytoremediation of NO2. Morikawa et al. (1998) noted variations of up to 600-fold in uptake and assimilation capacity of NO2 among 217 herbaceous and woody plant species and Magnolia kobus, Eucalyptus globulus, Eucalyptus grandis, P. nigra, Populus sp., Prunus cerasoides, Nicotiana tabacum, and Erechtites hieracifolia are found to be the most efficient species for the phytoremediation of NO2. Bidwell and Bebee (1974) investigated 35 woody plant species among which 17 (such as Acer saccharum, P. nigra, Gleditsia triacanthos, Pinus resinosa, and Fraxinus pennsylvanica) were specified for the ability to fix CO.

• Biodiversity: Trees and forests present in urban areas can provide shelter and habitat to many important animals especially avifauna.

• Management of Urban Hydrological Cycle: Through water provisioning, regulating, recharging and filtering roles, urban forests play a key role in supporting water management in and around urban settlements.

• Ecosystem services: Increasing ecosystem services with increasing of green cover in cities

SOCIAL BENEFITS OF URBAN FORESTRY

• Checks Haphazard Urbanization: Urban forests can check rapid and unplanned urbanization; development of slums by demarcating city limits and industrial spaces.

• Aesthetic Benefits:Urban trees enhance beauty and environmental quotient of the city and contribute to the aesthetic quality of residential streets and community parks.

• Improves Mental Alertness And Reduce Stress:Green areas reduce stress and improve physical health for urban residents while providing spaces for people to interact.

• Education: Urban forests in the form of parks, botanical gardens, zoological gardens, avenue trees and other urban green spaces are centres of education on flora and fauna.

• Recreation: Green parks provide a break from the busy, tiring, often repetitive and tedious routine jobs and works for people and safe playgrounds for children

• Cultural Regeneration:Urban green spaces can enhance cultural activities by providing venues for local festivals, civic celebrations, political gatherings and theatrical performances.

ECONOMIC BENEFITS

• Real estate prices:Landscaping with trees—in yards, in parks and greenways, along street , and in shopping centres—can increase property values and commercial benefits

• Employment: Tree planting and maintenance in urban forests can be labour intensive and provide work opportunities which may be especially important in poorer cities.

• Reduced energy consumption:Urban forest offers significant benefits in reducing building air-conditioning demand and reducing energy consumption.

CHALLENGES

There are many challenges which restrict the realization of urban forestry development in India and similarly in Punjab The problems of urban forestry are to an extent similar to those afflicting the social forestry and agroforestry development in India.

THE WAY FORWARD

The missing coordination between town planning at state and local government level, lack of initiatives to correct the imbalance, people’s narrow approach to just let things be as they are , why upset the apple cart , lack of planning and not pushing changes at the policy level. No holistic plan has been developed for the greening of the whole of Punjab which focuses on urban forestry as a focus area.

Keeping all the above in view there is requirement to set up a URBAN FORESTRY TASK FORCE headed by Minister of Environment with all secretaries of Forest, Urban Development, Local Government, Finance and Chairman PPCB so as to see a holistic policy,plan and speedy implementation with regular monthly monitoring  action taken report.

BUILDING AN ACCURATE DATABASE OF URBAN FOREST CHARACTERISTICS

A timely and accurate database of urban forest characteristics is fundamental to urban forestry for ensuring continual supply of their services to human well-being. While improving our understanding of the spatiotemporal dynamics of the provision of and demand for ecosystem services is the utmost priority (Wolff et al., 2015), pragmatic challenges exist when it comes to using remote sensing to achieve this goal. These include improving remotely sensed indirect measurements of ecological and hydrologic variables. However, three particular areas of research deserve future attention given the advancements in remote sensing systems, data acquisitions, and processing.

1. PhoDAR—it is an airborne photogrammetric technique for developing high-resolution 3D point clouds using photos taken from many different angles . PhoDAR has three advantages over other remote sensing data sources: (1) data accuracies are in the order of centimetres; (2) since photos are used to create PhoDAR data, it can be acquired using a fixed-wing platform rather than a helicopter; and (3) it is very cost-effective to acquire real-time data over areas inaccessible for ecological measurement. The entire process requires a UAV with a camera, GPS, and shareware for ingesting those photos (Eagle Imaging).

2. Interface between LiDAR and urban–rural forestry analysis and benefits assessment tools—most of the available urban forestry management software uses high-resolution imagery as direct input to map forest characteristics. It will be advantageous to use LiDAR or PhoDAR with high-resolution multispectral imagery together to yield structural characteristics of urban forest for assessment of ecosystem services. 

3. Real-time remote sensing—time-sensitive and dynamic events such as flash flooding, storm, and forest disease often threaten urban forest ecosystems. These events require constant monitoring, visualization, and rapid analysis to safeguard human and natural resources. Typical approach consists of classifying remotely sensed images. However, using real-time remote sensing data as input can help predict, visualize, and reveal hot spots of occurrences.

Ultimately, as research continues to broaden the usefulness of remote sensing to support urban forestry, a stronger connection among urban foresters, remote sensing experts, and programmers is key to ensuring the optimal provisioning of ecosystem services for human well-being by urban forests.

CONCLUSION

At the end I would say that if we treat this as a concept note for ushering in the urban forestry in Punjab the time is just so right because pollution is at its highest, unpredictability of climate change is evident in form of floods and unseasonal rains, high temperatures in normal cool months  so we need all the mitigation which we can achieve by bringing in urban forestry as fast as possible by a a vigorous and doable approach from the government to a local concrete courtyard of a town.

(A paper researched, compiled and written by the author)