(par 5.4.4.1) The importance of urban trees

By: Monika Koul* and A.K. Bhatnagar**

Adequate tree cover is important for economic and ecological security. Experts recommend that at least a third of India’s geographical area should be tree clad for sustainable environment and economic development. The total forest cover of our country as per 2005 assessment is 677,088 km, constituting 20.6% of the geographic area. Of this, the tree cover has been estimated as 91,663 sq. km, which is about 2.79 percent of the country’s geographical area (Forest Survey of India, 2005). Rampant felling of trees, on account of urbanization and developmental activities such as construction of roads and railway lines, is seen all over India. Data available on land use pattern clearly depicts that India has a skewed land use pattern. State of Environment India Report (2009) released by the Ministry of Environment and Forests states that over 50% of our total land is under agriculture, 17% is barren and uncultivable, 13% is culturable wasteland and barely 20% is under some form of the forests. The per capita forest area available in India is 0.06 ha, which is much below the world average of 0.64 ha per person. National Forestry Action Programme (NFAP) of Government of India states that besides protecting the existing forest resources, expansion of tree cover is important for maintaining the ecological balance. Therefore, plantations are to be carried out on the existing available pockets as well as areas which are devoid of tree cover. With no additional area available for afforestation, the focus during the last three decades has been on social forestry/community forestry and road-side/canal side tree plantations. With our towns and cities expanding rapidly, we need to think afresh about urban tree plantations too. These should not only contribute to aesthetics, but also add their bit to overall national tree cover targets and meet some of the residents’ small timber and non-timber plant product requirements.

Importance of trees in cities-aesthetics and ecology
India’s cities and their suburbs have expanded at the cost of farmlands, which in turn have encroached upon forests. Population explosion, economic development, industrialization and vehicular pollution are magnifying the urban problems and contributing to further loss of green cover. Nearly half of the population now resides in the cities and towns. The urban elite are conscious of the social and aesthetic value of trees. Yet, it has never been considered desirable that the cities should meet some of their own timber and firewood requirements. Cities need enhanced tree cover for their ecological needs-conserving soil and water and providing habitat for variety of life forms such as birds, animals, insects and microorganisms. The green belts also serve as lungs for purifying air in cities, act as sink for pollutants, check the flow of dust and aid in bringing down noise levels. Scientists all over the world are looking at trees in urban areas as entities which provide ecological services such as cleansing of the environment, recycling of the wastes, maintenance of seasonal cycles and acting as carbon sequestration units for mitigating the effects of global warming and climate change.
Most of the people responsible for urban development agree that plants contribute towards the environmental quality and there are ample social and psychological benefits of contact with plants. Recent public health research has deepened our understanding of the positive effects of plants on physical and mental well being. Social scientists have given conclusive evidence of the role of greenery in helping to cope up with stress and anxiety. Working and living near quality green spaces can satisfy people, help them relax and influence their mood and ability to concentrate for long. Urban pockets having adequate green cover harbour a lot of biodiversity too. The green patches serve as nesting ground for many birds, and act as macro and microhabitats for primates, rodents, insects, epiphytes, lichens, fungi and variety of other living organisms. Alternative habitats for a variety of living organisms in urban pockets enhance the aesthetic value of city landscapes and thus help in enhancing the scope of ecotourism. When the spaces next to residences are green, these become more attractive, comfortable and draw a lot of people to them. Such settings serve as foundation for social ties, ideal places for people to relax and children to play.

Present urban management practices
Why cities and towns should not produce some of their own tree-based requirements is a question which should now be discussed. The cities are a huge drain on forests and tree cover of rural areas for their timber and fuel/firewood needs. Urban centres draw huge quantities of wood from the forests and countryside, the poor for firewood and the better off for construction and furniture. Massive programmes and projects have been undertaken by government and non-government agencies to enhance urban tree cover over the years. Millions of saplings are distributed and planted each year in cities such as Delhi, Mumbai, Bangalore, Kolkata and Chennai. Tree plantations in most of the Indian cities are undertaken by horticulture departments or municipal boards or councils. The city councils plant large number of trees during the monsoon period, but fail to take adequate care during the dry period that follows. Juvenile mortality rate is very high. To achieve its full growth, a tree requires a lot of care during early years of growth. Attention has to be paid for proper placement of the tree in the ground, and its protection from ruminants. Many horticulturists recommend staking the young trees irrespective of the type of species to which the tree belongs. Since, most of the trees planted in city parks, on the roadsides, in the parking lots, in recreation parks and as shelter belts are taken from nurseries, a newly planted sapling in these areas requires manuring and irrigation at regular intervals. Novel soil reclamation and replenishment techniques need to be applied for improving the health of soil. This is very important for proper establishment of the tree in the new habitat. Compaction of soil in cities is also taking huge toll of trees. Many large trees are razed to the ground whenever there are strong winds and rain. Due to poor soil aeration, roots of such trees are shallow and weak. Concretization of roads is considered worst for the tree health. It causes choking of roots and hence injuries and death. It also results in destruction of flora and fauna below and above ground. Ministry of Urban Development and Poverty Alleviation has clearly specified in its guidelines that an area of 1.8X1.8m2 foot should be left “uncemented” around each tree to ensure that it gets enough breathing space. However, such recommendations based on common sense are not followed.
Road digging for laying cables and pipes are major threats, requiring saplings to be planted in the same place again and again. However, once the tree has survived, there is a total ban on its cutting, removal or even husbandry. Public perception, compounded by the media, is that once a tree has grown, it should not be cut or trimmed for developmental purposes even if it is overgrown, old or hazardous. The only way a large tree or its branches can fall is when there is a storm or rain. Extraction of non-timber products too is often not allowed. Pruning helps a tree to attain its maximum productivity, sustainable growth and tackles the requirements of fodder and fuel wood to some extent. It facilitates the growth of new shoots and formation of a wide canopy. Dormant buds after pruning produce new branches. If twigs and tops of trees are collected, and if old and underdeveloped trees are replaced regularly, it could help generate some wood and revenue and at the same time enhance landscape and organization of trees. Studies conducted on urban trees by Singapore Forest Department suggest that the average life expectancy of most of urban trees is about 50 years. Over the first three years of growth, 20% of the trees planted in urban areas die. Most show visible symptoms of aging such as loss of leaves, falling of branches and susceptibility to pests and pathogens. Such trees showing negligible growth over a time period and fewer number of leaves relative to the size of trees, should be allowed to cut and replaced by new saplings.

Species selection
Selection of trees for plantation is the most critical factor. What species should be planted is much less a matter of concern now than it was when many of our large cities were planned. Trees in older planned areas of Hyderabad, Pune, New Delhi, Lucknow, Kolkota, and Bangalore are far more diverse and systematically planted than in the newer townships and suburbs. A comparison of the trees planted in major cities before or just after independence with those being planted now would be very revealing. The British introduced hardwood trees in India from their other colonies through specially created arboretums and gardens in Kolkata, Bangalore, Darjeeling, Ooty, Dehradun, Saharanpur, Panchmari, Manali and elsewhere. Establishment of city national parks in Mumbai and Chennai and botanical gardens in Lucknow, Bangalore and Kolkota are some examples of well thought out and well planned urban green belts. The reforestation of Delhi Ridge (1912) and declaration of Delhi Ridge as a Reserve Forest is also a milestone in conservation of urban greenery. Considering the strategic importance of these green belts, species selection, introduction of exotics and landscape features were given considerable attention. In the concrete jungles these still serve as green lungs. The present day municipalities, despite their huge budgets and jet-set executives and councillors, neither follow the traditions nor have introduced any innovations in their tree plantation programmes. Trees that can be multiplied easily and require no post-plantation care are the favourites. Thus, we can see on most of the roads a mixture of big and small trees of eucalyptus, casuarina, ashoka, alstonia, neem, banyan, mulberry and sisoo. Beautiful palms, conifers and ornamental trees such as corals, flame of the forest, silk cotton, bauhinias, crape myrtle, temple tree, bottle brush, Indian laburnum, gulmohur and squirtwort are rarely planted now as these are considered ‘commercial’, prone to pilferage and difficult to sustain. The regulation and publication of Gazette Notification defining the trees that can be planted by official agencies in a major city also leaves horticulturists with much less choice in selection of species. Dr M.S. Randhawa, in his book entitled ‘Flowering Trees, ‘ has mentioned that during the British rule evergreen tree plantations gained more attention. Trees such as tamarind, arjuna and African sausage tree were seen as good for hot summer climate. Plantation of beautiful deciduous trees which formed an important component of the vegetation was seriously neglected. By recommending a preponderance of ever green species’ for the arid habitat in Delhi many native species were edged towards local extinction.

Incidentally, many trees with wind borne pollen, which cause allergic disorders in a substantial part of the human population, still find place on city roadsides. Such trees, including eucalyptus, wattle and mulberry are in the lists of permissible trees in many cities. It is observed that in Delhi multiple government agencies viz. Delhi Development Authority (DDA), Municipal Corporation of Delhi (MCD), Cantonment Board and Forest Department continue to plant several allergenically significant trees.

Selection of trees for plantation in urban areas revolves around convenience. The basis of selection is very narrow. Saplings raised on mass scale are distributed and planted without taking into account the importance and the role the tree is going to play in a particular habitat. The concept of landscaping is still alien to our planners with the result that the trees are haphazardly planted, and the trees planted on roadsides are no different from those in parks or schools, offices and hospitals. Some of the most beautiful trees flower during February-March, coinciding with breeding season of several birds. The flowers provide nectar to the birds in return for pollination service essential for their reproductive cycle. To attract birds, the trees produce beautiful flowers. The bird-pollinated trees, such as silk cotton, flame of the forest, Indian coral tree and Bauhinia spp. make the landscape majestic. The African sausage tree is pollinated by bats. The Arjuna has fruits that are chewed up by bats that help in seed dispersal. Manila tamarind has a red aril covering a part of the seed which attracts birds.

Thus, a variety of trees support different birds, bats and insects and make the human habitat lively and biodiversity rich. Rare and endangered species of trees can be reintroduced in certain pockets as is being done in the Aravalli foot hills in the NCR. Kala siris (Albizia odoratissima), frankincense tree (Boswellia serrata), kulu tree (Sterculia urens) and pisangan (Grewia flavescens) which were the charac-teristic of Aravallis can be reintroduced in the city forests of Delhi and Jaipur. Many cities can be safe heavens for RET trees. Multipurpose trees, especially those of medicinal importance, can be introduced in some selected pockets where adequate care can be taken. Since, natural products are already catching frenzy of city populations, such introductions can also help in revenue generation. Trees such as emblic myobalam, soapnut, marking nut, drumstick, neem and butter tree which were once important components of vegetation of many cities should be grown more frequently. A planted area as a whole with trees, shrubs and a ground cover forms a living and dynamic system with better ecological services. The selection of trees for plantations should be done in accordance with the type of land/pysico-chemical properties of the soil available for plantation.

Estimation of green cover
A flaw with the estimation of green cover is another area which eludes the urban foresters. Tree records, based on number of saplings planted, and remote sensing data depicting everything green as a part of tree cover, often give exaggerated data. Phytosociological and quantitative vegetation analysis procedures, giving more precise details of about density, abundance, basal cover area and canopy cover area, need to reinstated and used to supplement satellite data. The government machinery is often confused and stands divided on many aspects related to management of tree cover. Focus has always been on the number of trees planted each year. Monitoring on the basis of tree clad area can give better picture of the city’s green area. Research in urban forestry and management of trees is yet another area where no public funding or interest is apparent. Lot of research is carried out on management and improvement of forest tree species. However, urban trees growing in different ecological settings are not being studied. Ministries and other funding agencies need to allocate funds for research on ecological, economic, aesthetic and psychological aspects of urban trees.

Mitigation of climate change
With the United Nations Framework Convention on Climate Change (UNFCCC) now allowing countries to earn credits for planting trees, which function as carbon sinks, the cities can earn carbon credits under the clean development mechanism (CDM). Delhi and Himachal Pradesh have already identified land for tree plantation and agreed to increase the green cover and earn these credits to boost their economy. Such plantation drives are already taking place in tropical countries. Singapore and Malaysia are front runners in their profitable endeavour because of enhanced green cover and modern scientific tree management strategies.

Recommendations
Urban forestry practices in India are anachronistic. A paradigm shift in planning and management framework is required for tree plantations to be aesthetic, cost-effective and of multiple utility. The choice of species needs to be expanded to include a much larger diversity of the indigenous and exotics. Ornamental trees, mostly insect and bird pollinated, will add some colour to drab landscape of Indian cities. Palms and conifers at appropriate locations can help break the monotony. Trees deserve more care and hospitality, especially in the early stages. Regulations that limit replacement of old, diseased and crooked trees, or those at unsuitable locations, need to be dropped, and urban greenery should increasingly be treated as dynamic, productive systems. The large, resourceful horticultural and forestry departments in major cities should invest in tree improvement, landscaping and resource utilization technologies. Many RET and medicinal trees can be conserved in urban plantations, to take off the pressure in the wild. The present method of fixing targets based on number of saplings planted annually also needs to be replaced with modern methods of tree cover and biomass assessment by remote sensing. Trees that are good in carbon sequestration can help mitigate climate change, and in addition earn carbon credits. Finally, involvement of citizenry, through education and incentives and individual choice and care of trees will go a long way in fostering good people-tree relationship.

*Assistant Professor, Department of Botany, Hans Raj College, University of Delhi, Delhi – 110 007 E-mail: drmkoul@gmail.com
**Professor, Department of Botany, University of Delhi, Delhi – 110 007 E-mail: akb_du@rediffmail.com

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