Nature under threat | The Key Roles and Functions of Trees as a Global Public Good

Over and over again, in the name of development, Nature is sacrificed for a perceived benefit to human society. Such is the case for the destruction of 270 trees along Promenade Roland Armand along Vandermeersch Street, Rose-Hill, to make way for the Metro Express Project, for which a proper Environment Impact Assessment (EIA) has apparently not been made. There is much debate around the benefits that the Metro will actually provide in facilitating the mobility of our citizens in this part of the island. Organisations like 270 Lavwa, FreeArt and RAFAL have given their reasons why they are against the destruction of the trees at Promenade Roland Armand and Jardin Bijoux. The question is whether the benefits that Metro will provide, will outweigh the loss of existing ones that inhabitants are currently enjoying whether knowingly or not. To add to this debate, it is good to recall the key roles and functions that trees play in our life and what the loss of the trees would mean, not only to the people living in the area, but to society as a whole.

- Publicité -

Trees are an intricate part of all our ecosystems and provide the provisioning, regulating, cultural and supporting services amongst others. They have much impact on the immediate environment and on the socio-economic health and wellbeing of people. Without trees it is certain that life on earth would be much more turbulent and climate effects more extreme. Trees are the lungs of our planet. By the process of photosynthesis, they absorb carbon dioxide and release oxygen in the atmosphere, thereby regenerating our oxygen supply. They serve as carbon sinks, which if otherwise left in the atmosphere would contribute to global warming through the greenhouse effect. Just to give you an idea, ‘a single 40-year old tree can sequester as much as one ton of carbon dioxide’ (carbon-tree-facts). Trees, even as isolated individuals, can make a significant contribution to improving the quality of their immediate environment.

Besides this fundamental function, tree species provide us with sources of foods, medicines, clothes, ornamentals, building materials and other uses. ‘We know that trees hold up the mountains, cushion rainstorms, control floods, maintain springs, break the wind, produce food, foster birds, and many other functions. They create and hold soil, thus stopping soil erosion and preventing landslides.’ (Edward Milner).

Trees play an important role in water flow, thereby regulating our ecosystem. They absorb water from the soil by their roots, sometimes from deep down, and bring it up to the canopy. In one day, ‘one large tree can absorb up to 100 gallons of water’ and release it into the air by a process called evapotranspiration, thereby cooling the surrounding area. This creates a pleasant microclimate that benefits the local inhabitants, be they people or other living organisms. With the trees gone, the local climate will change and the quality of life in the neighbourhood will certainly decline.

Trees are habitats for local fauna. Some trees with hollow trunks provide shelter and nesting-places for birds and other animals. In Mauritius, many endemic birds such as the Mauritius Parakeet and Kestrels nest in the hollow trunks of native trees. Among the remaining endemic birds of Mauritius, only one species, commonly known as pic-pic, has been able to adapt to the urban environment. One can admire these beautiful birds along Promenade Roland Armand, flying among the trees to seek nectar from the flowers of the bottle brush trees. I remember that in the 1970s and 80s, our now defunct Conservator of Forests Wahab Owadally, introduced bottle brush trees along roadsides and avenues to provide habitats and nectar for endemic nectar-feeding birds.

Besides the biological and environmental benefits, trees have great cultural, spiritual, aesthetic, medicinal and health values. Many tree species play an important role in the development of human cultures throughout the world. Several indigenous and local communities have a deep knowledge about plants and their use as medicines, in traditional customs and rituals, and have sustainably conserved a vast diversity of plants (Dulloo et al). Many tree species are considered as sacred. For example, “the sausage tree (Kigelia africana) is believed to shelter spirits for female fertility and it is forbidden to cut it in the communities where it is sacred”. In Madagascar, the massive Baobab trees are also regarded as sacred by local communities. The peepal tree (Ficus religiosa) “is the tree under which the Buddha is said to have reached enlightenment, while Hindus regard it as a place of dwelling for Brahma, Vishnu and Mahesh” (globaltrees.org).

“Medicine from trees, extracted from the wood, bark, roots, leaves, flowers, fruits or seeds, is fundamental to the well-being of millions of people around the world. Where access to modern pharmaceuticals is limited, trees offer living pharmacies open to anyone with traditional knowledge on their medicinal properties” (globaltrees.org). A good example is the Cassia fistula tree (“fler Cavadee”) (whose flowers are also used in religious rites) with beautiful yellow flowers, which we can encounter on the Promenade Roland Armand. The bark is extensively used by Ayurveda medicine in the treatment of inflammatory swellings and as a cleaning agent for ulcers and wounds. It is believed to decrease purulent discharge and act as a local antiseptic. The fruits are also used as a laxative.

“Trees reduce air pollution by trapping particulate matter in their leafy canopies and by absorbing noxious pollution into their leaves. The particulate matter is eventually washed away with rain. After leaf fall, absorbed pollutants are incorporated into the soil where they are broken down by microbes. These actions reduce human health problems related to air pollution” (Kane B). It is evident therefore that with the destruction of the trees along Vandermeersch Street the quality of the air will not be the same as before and the risk of the inhabitants contracting respiratory diseases would increase. Furthermore, trees along the Promenade provide shade for the passers-by and many inhabitants use the shaded Promenade for healthy exercises such as walking and jogging. The shade that trees provide to roads, buildings and other structures help reduce energy consumption.

Along Promenade Roland Armand there are many highly ornamental trees, characterised by beautiful flowers of various colours, that have been planted to improve the aesthetics of the neighbourhood.  One of the most majestic trees along the Promenade is the cotton tree (Bombax ceiba), which produces huge red flowers when the tree is devoid of leaves. Several other species add colour to the Promenade, like the Jacarandas with their mauve flowers, the Cassia fistula with its pendulous yellow inflorescence, the Flame-tree or Flamboyant (Delonix regia) with red flowers. The Tecoma tree (Tabebuia rosea), with pink flowers, is one of the most beautiful examples of this species I have seen in Mauritius.

Despite all these benefits we get from trees, we humans are continuously undoing all that trees are doing i.e. adding more carbon dioxide, other forms of pollution, soil erosion, destruction of biomass, reducing water absorption capacity of soil, destroying the micro and the macro flora, etc. We continue to cut down trees indiscriminately. We do not realise that the destruction of trees will lead to increased economic stress on both private individuals in the immediate vicinity and society at large, in terms of reduced property prices, higher energy costs, etc. Indeed the services provided by trees are worth billions of rupees per hectare; this is taken for granted and is not accounted for in our economic balance sheet.

There is a trend in Mauritius that the number of trees within the urban areas is declining. Gone are the days where private compounds had lots of decorative and fruit trees in the garden. Many fruit trees are becoming scarcer and scarcer. With scarcity of land, large compounds are being divided up (morcellement) to make way for new constructions and trees are felled down. What is needed is a much better protection for trees, especially in urban areas. It seems that we do not have the right policies and regulations in place to ensure that the global public good and services trees provide to our wider society are maintained for an improved environment and quality of life. Unfortunately, even when such regulations do exist their implementation and enforcement can be a big challenge. This has happened in the case of the Metro Express project when it was decided that there was no need for any EIA. The requirement for an EIA Licence for that particular project was simply waived! In other words, come what may, the project had to go ahead. Who would pay for the consequences? Inhabitants of Beau-Bassin–Rose-Hill!!!!

Ehsan Dulloo is a conservation biologist of international repute. He works for

Ehsan Dulloo Ph.D
An inhabitant of Beau-Bassin-Rose-Hill

Bioversity International where he is Team leader of their Conservation programme. He has also worked for Food and Agriculture Organization of the United Nations. Before his international career, he was assistant conservator of forest of Mauritius and also worked for the Mauritian Wildlife Foundation. He helped in the establishment of Black River Gorges National Park and in the restoration of our degraded forest in Mauritius and Rodrigues and islets such Ile aux aigrettes and Round Island.

- Publicité -
EN CONTINU

l'édition du jour