Creation of urban forests will help maintain good , predictable weather

We shall wake up to a polluted, desert-like Uganda which we have all participated in inviting.

With temperatures soaring over 30 degrees Celsius, its easy to joke that frying an egg under Kampala’s heat is possible. One question to ponder over is, what is the solution to this problem especially in the urban areas?

Its a great pity that our towns are mostly lined with buildings, many of which are poorly planned, curving out any chance for existence of green belts. Why are we quick to plant ceremonial trees which hardly even survive longer than a year rather than embarking on reasonable environment protection and conservation through projects like urban forestry? We should stop bickering over the extremely hot weather, especially during the hot seasons and the consistent flooding during rainy seasons, and roll up our sleeves for action. Otherwise, we shall wake up to a polluted, desert-like Uganda which we have all participated in inviting.

According to Internet sources, an urban forest is a collection of trees that grow within a city, town or a suburb. In a wider sense, it may include any kind of woody plant vegetation growing in and around human settlements. While in a narrower sense (also called forest park) it describes areas whose ecosystems are inherited from the wilderness.

The benefits of urban trees are numerous which among others includes beautification, this contributes to an attractive, orderly and eye catching surrounding. Tree shades and other urban green spaces, for instance recreational parks, make place for people to meet, relax, socialise and play thus connecting with nature and basking in its pacifying ambience. Other benefits of urban forestry include:-

Reduction of the urban heat island effect: Urban heat island is where a metropolitan area is significantly warmer than its surrounding rural areas. This is mainly a result of modification of the land surface by urban development, often using materials that effectively retain heat. Another secondary contributor is the waste heat generated by energy usage. And since there are no urban forests or enough trees surrounding our buildings, there is lack of evapotranspiration.

Mitigation of the urban heat island effect can be accomplished through planting and maintenance of sizeable urban forests. These will also help in cooling our cities and improving air quality.
Reduction of air pollution: The most serious pollutants in the urban atmosphere are ozone, nitrogen oxides (NOx), oxides of sulphur (SOx) and particulates in air. Ground-level ozone, or smog, is created by chemical reactions between NOx and volatile organic compounds (VOCs) in the presence of sunlight. High temperatures increase the rate of this reaction.

Vehicle emissions, emissions from industrial facilities, gasoline vapours, and chemical solvents are the major sources of NOx and VOCs. These can be inhaled and retained in lung tissues causing serious health problems. Trees help to reduce pollution by actively removing pollutants or by partially mitigating the effects of atmospheric pollution. Leaf stomata, the pores on the leaf surface, take in polluting gases which are then absorbed by water inside the leaf.

Ideally, trees should be selected that take in higher quantities of polluting gases and are resistant to the negative effects they can cause.

A study across Chicago region determined that trees removed approximately 17 tonnes of carbon dioxide (CO2), 93 tonnes of sulphur dioxide (SO2), 98 tonnes of nitrogen dioxide (NO2), and 210 tonnes of ozone (O3)
Reduction of storm-water run-off: Storm-water run-off is rainfall that flows over the ground surface. It is created when rain falls on roads, driveways, parking lots, rooftops and other paved surfaces that do not allow water to soak into the ground causing stream impairment in urban areas.

Trees and forests reduce storm-water run-off by capturing and storing rainwater in the canopy and releasing water into the atmosphere through evapotranspiration. In addition, tree roots and leaf litter create soil conditions that promote the infiltration of rainwater into the soil. This helps to replenish our groundwater supply and maintain stream flow during dry periods. Reduction of energy costs through increased shade over buildings, enhancement of property values; Urban forests also act as wind-breakers, and mitigate the overall urban environmental impact.

Let us all care for our environment. Politicians and leaders should not only be bent on winning elections but also on patriotic issues like environmental protection and nature conservation. KCCA is trying hard but the public is not supportive. It is not uncommon to see people along Kampala road stepping on the grass even though its protected. Embracing urban forestry in Uganda is crucial considering the ever growing effects of global warming.

rkatham@yahoo.co.uk