Effect of Urbanization on Urban Forestry and Air Quality- a Case Study of Ngong Road Forest Nairobi, Kenya

Abstract

Urban forest though playing a vital role in sequestering air pollutants in cities, they have been on the verge of depletion due to rapid urbanization of cities in Sub-Saharan Africa including Kenya. The research aimed on studying the effect of urbanization on the Ngong Road Forest cover and air quality. The study employed household survey for collecting primary data from communities living within around the forest, within a distance of 5km. Past imageries of four scenes 1988, 1999,2008, and 2019 were analyzed using ArcGIS, ENVI and Google earth engine. A total of 219 respondents were interviewed using household survey, key informant and FGD. Correlation analysis was subject to the data. Generally, 37% of the forest cover was converted to other land uses, where built-up areas accounted for 74%. The statistical analysis shows that there was strong negative correlation between the expansion of the city and forest cover (R; 0.903, R2;0.810). Between 1988-2019, urbanization has led to significant deforestation, this will potentially reduce the forest ecosystem services. By the year 2030, if no stringent actions are taken, the forest cover will reduce to as low as 600 ha, thus will contribute to poor air quality. The study found this significant deforestation was mainly due to illegal logging, as the need for wood for construction and fuel increased. 49.8% of the respondents indicated that illegal logging as the main factor that led to deforestation. Others attributed it to land grabbing (22.4%), infrastructural development (13.7%) and poor forest governance (7.8%). In regards to forest governance and practices, the study found that there is a relation between gender and level of community involvement in decision making process (p-value less than alpha value, 0.01<0.05). Women were not effectively involved in forest decision making process. This might be due to cultural norms as well inadequate measures taken by CFA and KFS in regards to gender mainstreaming on matters related to forest governance and management. The local communities plant trees for various reasons, majority did plant for domestic use (68%), while other did so during reforestation programs (17.8%), for commercial (13.2%) and medicinal purpose (0.9%). Majority of the households near the forest rely on non-forest businesses (71.7%). While the rest rely on farming (15.5%), livestock (2.7%), charcoal businesses (2.7%), tree nursey business (6.4 %) and timber business (0.9%). In regards to source of energy for cooking, majority rely on LPG (45.7%), while others rely on firewood and charcoal (19.2%) as well on electricity (14.6%). The study further found that household’s average income and their level of access to forest products are related (p-value less than alpha value, 0.01< 0.05) though majority had no access. In regards to air quality, 82.6% of the respondent indicated that the air quality has declined in the last 30 years, where majority of them (54.8%) attribute this to deforestation, 19.6% and 5.9 % ..........................