Urban Forestry: Oilseed Trees in the Cityscape

By Ravi S. Behera and Ranjit K. Sahu

Creation of wealth, its distribution and management was being increasingly highlighted as the means to attain development before the concept of sustainable development began to replace the concept of development. With the realization that most resources like land are finite and the problem of population magnifying the issues unemployment, health care and nutrition it is time to rethink of non-conventional sources of sustenance.  Recycling is being promoted as a means to curb pollution s well have less negative externality. However one untapped resources that has been overlooked that comprises of all the above is the possibility of using products from urban landscapes. Roof top gardening has been a trend. However this would still be private affairs or in individual scales and in the busy life of city dwellers may at best be a cosmetic effort unless serious legal means are employed to implement it. We therefore examine a new possibility of using the long stretches of  roads and streets as a possible source of  non timber forest products (NTFPs) by effecting a recovery of overlooked products like seeds and fruits.

There has been a lot of hue and cry   about decreasing forest areas all over the world and in India.  While population explosion and encroachments of forest lands by mining and timber mafia as well as government sanctioned orders for construction activities are being blamed, the less observed factor of increasing urban spread needs to be considered as well. Such urban expansion often leads to the destruction of not only forested areas but also water bodies (as in the case of Bangalore), river catchment areas (as in case of Yamuna River). This in turn decreases both the green cover as well as the water absorption and retention capacity of the soil, leading to floods and drought and lowered water tables. In view of these issues that are increasingly being experienced across cities in India. The recent order by the Parisian authorities making roof gardening or solar panels compulsory may be one approach to recreating some of the green cover and decreasing solar insolation. Additionally the approach of growing algae on the highways as being experimented in Europe maybe possible feasible solutions. We look at the other aspect of trying to recreate an urban forestry system and the possibility of making it utilitarian in nature so that people are dependent on it making it a part of their survival. Such approach would inevitably lead to protection of the trees especially in the alleys and avenues of major cities apart from making the city aesthetically pleasing.

More often than not cities are lined with ornamental trees that produced flowers and are often of exotic nature. Due to concerns of global warming and the resultant effect it may have on all life, it is prudent to search and utilize local trees which are more adapted to native conditions for cityscape purpose. One way would be to Tag these trees with an economic benefit.

We observed that trees like karanja (Pongamia pinnata) that have dense foliage and are native to the Indian subcontinent may double up as also oil seed crops if properly managed. A mature tree of Karanja produces 8-90 kilograms of seeds and such trees when lining the avenues would shed the pods on the sidewalks (Figure 1c). This not only acts as an eye sore to pedestrians but also can lead to creating a problem in traffic. Moreover these seeds can sprout in the monsoons in unwanted places, further complicating their management. The municipality that is often starved for funds can instead utilize these wasted raw materials to obtain some revenue. While the collection of such pods by authorized personnel can lead to employment of less skilled work force, the seeds can be utilized for extraction of oil and the oil seed cake can be used for other purpose sin the urban areas like organic manure. This would not only help maintain a cleaner environment but also add to ecological sustainability. Additionally the regular pruning of these trees can be carried out by less skilled workers and the twigs which are used as tooth brush can be promoted as a healthy option in an increasingly aware society.

The above ideas may not be suitable for implementation in areas already congested with buildings where space is limited but can be included in urban planning of newly developing areas. Since aesthetic considerations are important as well, these trees maybe planted either alternately to flowering trees or in short stretches between flowering trees to maintain beautification along with the economic benefits from these trees with minor products. Compared to fruits trees like jamun and mulberry which have a potency to disfigure environment through stains with berries, karanja trees maybe more aesthetically appealing. Thus the trees with fruits can be designated to areas where there is likelihood of wildlife inhabitation. In areas where trees already exist, when any dead or damaged tree is removed it can be replaced with these types of trees with potential for oil seed production. While it may look like a small number, even if 10% of a cities avenues and alleys are lined up with such trees it would cumulatively lead to a substantial amount of oilseeds.

The ecologically important regions of the world like the Leuser ecosystem in Indonesia and the Amazon rain forests are being decimated for palm oil production. While the general notion is palm oil is used for food purposes, the overlooked aspect of it is it is also being looked as a source of bio-fuel which based on recent reports was the biggest consumer of palm oil. Thus the trees like oil palm may also be examined as avenue trees instead of date palm. These tree oils may be a source of bio-fuel and using the cityscape may help partially reduce the pressure in the tropical forests for cultivation of trees like oil palm in land required for agro-forestry.

Thus native trees like neem, karanja and Simarouba may be given preference where possible in cityscape planting along with suitable guidelines for utilization of these natural resources which can not only add to the revenue but also help in environmental sustenance. A list of trees which maybe considered in this regard is mentioned below. It may be time to think of using spaces within cities and the growing lengths of highways for introducing urban social forestry concepts as the real forest is sinking.

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Photo: A karanja tree on the street, the dense foliage and pods on the sidewalks.

Author contributions: RKS and RSB contributed to the, conceptualization and drafting. Photo credits RSB.

Dr. Ranjit K. Sahu is a freelance writer currently located in Virginia, USA. His interests include education, environment, sustainability and health care in the underprivileged regions of the world.

Ravi Shankar Behera is a free lance consultant in the development sector and affiliated to several organizations, currently based in New Delhi and Bhopal.


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