Arborization to improve urban climate conditions in Brazilian cities

This paper deals with the inclusion of urban thermal comfort issues, particularly arborization, in local regulations in Brazil. It presents success and mistakes of some Brazilian cities and a more detailed study for a city of more than 600.000 inhabitants in the Middle West region of Brazil, Cuiabá, that does the very first attempts to include taxes incentives favourable to the improvement of environmental conditions. Ideas and results of various arborization programs in the main Brazilian cities are analyzed. But despite the relevance of urban forests, we do not have to mystify this issue; in Brazil there is a federal law that establishes that 35% of the municipal area is public, of which 15% have to be destined to green areas, but no one says who is going to pay for their maintenance. When we talk about urban environment we need to maintain clearness in the discussions and think on more practical terms, without any ideological intention. To maintain urban forests it is necessary to have an arboretum with a satisfactory production; producing cuttings, planting and maintaining trees costs money, and we cannot leave the responsibility only to the government; we can think on private alternatives. Based on climatic data recorded in one of the main Cuiabá growing axes in 1998/99 and 1992/93, a slight temperature increase were found for the last 6 years, suggesting that measures related to thermal comfort must be incorporated in planning, specially in developing areas. The Land Use Law recently approved as part of the General Plan has proposed, among others, to raise population density to limit sprawl and to reduce the city’s services costs, as intended by other Brazilian cities like Curitiba and São Paulo. Curitiba, for example, follows the principle that occupation and land use can be induced in a way that population density could be compatible with infrastructure availability. Climatic alterations point that the rising density intended by the general plan to reduce urban infrastructure costs must be conducted with caution to not aggravate urban thermal comfort conditions. In the new settlements, for example, the wider avenues, nowadays inevitable because of traffic, should be compensated by humidification and shading, because we cannot count on confinement as in the narrow streets of the old core. Cuiabá already has successful partnerships of private enterprises to plant and maintain trees on downtown green squares in return for publicity and the city does the very first attempts to include taxes incentives favourable to the improvement of environmental conditions. There are positive points in the actual regulation, as the taxes incentives to maintain adult trees in the lots and the requirement of consolidated public arborization to the medium standard occupation pattern forward. Now the government has to inform the population, to incentive this practices, to attend these initiatives implementation and to supervise the execution of the law.