The Assessment of Deforestation Impact Towards Microclimate and Environment in Ilorin, Nigeria

Nigeria obtains high rate of deforestation with a loss of about 60 percent of its primary forests between 2000 and 2005 as a result of logging, subsistence agriculture,wood exploitation, and urban expansion.This research assessed the level of deforestation and how it has affected Ilorin’s microclimate and the environments. The specific objectives of this study were assessing the relationship that occurs between deforestation and microclimate, examining deforestation and the impact it has within the study area of microclimate, and forecasting the microclimate within the study area by the year 2030. The statistical tools engaged were both descriptive (mean, frequency distribution table and, bar charts) and inferential statistics (multiple regression analysis). The research indicated that there isnansignificantmrelationship betweenmdeforestationmwithmrvariables ofm0.888 formmaximum temperature,m0.201 for minimummtemperature,m0.997 formprecipitation,m0.43 formsolarmoutput,m-0.797 andm 0.873 for evapotranspiration and relative humidity respectively and Ilorin’s microclimate. The study concludes that deforestation greatly influences the microclimate of Ilorin and occurs due to human’s anthropogenic activities. Deforestation has also led to climate change.


Introduction
Human's relation with the environment has transcended through ages. Although, the human is the subject upon natural controls and events, the human acts as the dominant force establishing major long-term environmental challenges, one of which is forest degradation.
For a long time, population increase has led to the removal of vegetation cover to meet the urban expansion demands. This has allowed for the thriving of deforestation without proper consideration towards the impact on the environment at large. Vegetation cover is major reservoirs for carbon sink, managing to regulate temperature as well as the layer of harmful gases concentration (greenhouse gases) within the atmosphere. However, deforestation increase has allowed the contiguity of more GHGs into the environment providing a microclimate that is heated up and unobligated. It is recognized that the more house/population grows, the more climatic variables appears into the environment.
In Ilorin, it is palpable that a major factor responsible for climatic variations is deforestation. Deforestation has been noticed to have accelerated in many countries with the tropical regions, such as Nigeria. Although reliable estimates are not available, it has been put at approximately 285,000 ha annually (Chakravarty et al., 2012). At this rate of deforestation, 50% of the country small forest land area had 10% of total land area being eliminated in 2015 (WWF, 2017).
Deforestation is the alteration of the forest to non-forested land conducted by the human. It occurs due to human demand for certain services which might be promoted for conversion or adjustment upon the land that is dominated by naturally growing trees into a land that suitable for the needs of the growing population (Kumari et al., 2019). Globally, tremendous pressure has been put on wood land settings as a result of deforestation and forest dilapidation. From 2010 until 2015, approximately 122.29 million hectares (Mha) of tree cover were disappeared (WRI, 2020). This number reached about 5% of the total area covered by natural forests in 2010. Deforestation and other land utilization shifting are now considered as the second major anthropogenic source of Green House Gases (GHG) emissions, and a significant contributor towards climate change. A large proportion of the carbon dioxide (CO2) is brought into to the atmosphere as the results of people activities that are being absorbed by trees and other vegetation which enhance to soothe the potential climate change impact (Milman, 2018). A great proportion of annual global greenhouse gas emissions ranging between 12 percent and 17 percent are the consequences of forests lost (WRI, 2010). A major threat and concern towards people and the environment is deforestation both in small cities or towns and the gobal world in general (WRI, 2020). It continues to occur at alarming rates. Hence, it contributes greatly to the ongoing loss of biodiversity and increases the emission of several gases leading to global warming.
A study performed for the Centre for International Forestry Research (CIFOR) in Congo Basin revealed that several causes could be identified as deforestation factors. The direct causes namely infrastructural development or agricultural expansion while the most striking cause is economic development or population expansion. Nevertheless, agriculture constitutes the major factor of deforestation (Tchatchou et al., 2015). Among some countries, Nigeria has the world's highest deforestation rate of primary forests (Daramola et al., 2015).
Toluwalope Mubo Agaja et al / GEOSI Vol 5 No 3 (2020) 301-317 Issues are brought by land tenure system and the growing population rate are identified as the major factors of deforestation (Su et al., 2011). The driving forces of high deforestation rates are demographic, institutional, cultural, economic and technological policy (Adeleke et al., 2017). As the demand for land expansion is growing, forested areas are rapid to be depopulated in order to provide logs for community construction, and a host of other amenities they may establish within the environment (Daramola et al., 2015). These changes promote urban areas into hotter place than rural surroundings which is as a result of human's behavior that managing areas with warmer temperatures in the environment (USEPA, 2017). Therefore, the heat has a tendency to spread out to other parts of the city, that affecting the microclimate. Vegetation cover helps to absorb carbon within the atmosphere that acts as the carbon sinks. Due to logging, the vegetation cover is reduced in size leading the inclination of CO2 being attached and the increase in the CO2 in the environment that enhancing the higher surrounding temperature (Senior et al., 2018) Forests circumstances are changing significantly throughout the world and currently driving the climate which results in an imbalance in water, energy, and carbon on the land surface (Li et al., 2016). There are three rationales to identify a solid relationship between forest/vegetation structure and microclimate. Firstly, the proportion of energy penetrating through to the soil is reduced as the plant canopies absorb, scatter and reflect back the solar radiation received. Secondly, plant canopies absorb momentum from the air and thus wind speed decreases with depth within the canopy. Hence this suppresses turbulent of air mixing by vegetation. Thirdly, the water vapour amount is strongly depending upon the air temperature (Hardwick et al, 2015).
An increase of bare surface indicates an escalation of the surface temperature and conversely affects water bodies, as the rate of evaporation increases that brings water to drive away towards the atmosphere in gaseous form. A study reported that satellite data showed that forest-covered area globally and above land temperatures are the results of forest losses directing towards deforestation zone suffering an increase of temperature variations (Cescatti, 2016;Chapman et al., 2020). Deforestation has increased the environment temperature as being compared to emissions comes from carbon dioxide under other anthropogenic activity.
The urgent of identifying the relationship between forest cover change and the temperature has become very critical since the rate of forest loss continues to rise and as a result, a shift in the local climate becomes distinct (Odoemene, 2017). Urbanization, agricultural expansion and deforestation have affected climate temperature that indicating to deteriorate and a significant approach to mitigate the heat island effect is performing tree planting (Wolff et al., 2018).
Greenhouse gases are absorbed by trees and this stage plays a crucial part in reducing the risk on global heat. Therefore, enormous proportions of calamitous gases bump into the atmosphere will likely increase and hastening the severity of global warming (WWF, 2017).
An environmental consequence that being examined upon this global forest change in terms of deforestation or afforestation is microclimate changes (Prevedello et al., 2019).
Several studies have attempted to assess deforestation and how it has affected several aspects of global climate (Daramola et al., 2015;Li et al., 2016;Prevedello et al., 2019;Kumari et al., 2019;Wolff et al., 2018). In this term of study, there are limited studies concerned about microclimate and how deforestation has greatly forced it. The high rate of changes occurred in Ilorin in terms of land-use shifting from forested land to a construction area is distressing and needs for discretion. As a result, there is necessary to fathom the microclimate, as it deals with the domestic weather conditions upon study area and a swift change could occur as a result of anthropogenic activities that deforestation is a major one.
Therefore, the aims of this study were to examine deforestation and the impact towards the micro-climate of the study area, to assess the relationship between deforestation and microclimate, to predict the rate of deforestation by the year 2030 and the impact of the microclimate towards study area.

Methods
Ilorin is located between latitudes 8 o 24 ′ and 8 o 36 ′ North of the equator with longitudes 4 o 10 ′ and 4 o 36 ′ East of the Greenwich meridian ( Figure 1). Ilorin covers an area approximately 468 km 2 . It is 200 km from Abeokuta, 512 km from Sokoto, 574 km from Calabar, 1,013 km from Maiduguri and 494 km from Aba. Ilorin experiences humid tropical climate characterized with 7 to 8 months of rainy seasons. The dry season starts in November and extends to February (Daramola et al., 2015). The total average of annual rainfall in Ilorin is 1200 mm. Ilorin's temperature ranges between 34 ºC to 37 ºC from February to April, while months between November to January, the value ranges from33 ºC to 35 ºC (Ajadi et al., 2016).MThe soil in Ilorin is Ferruginous in nature (Iroye, 2017). This soil is suitable for crops growing such as yam, cassava, maize, and etc. The land utilization of Ilorin for some years back were primarily agriculture and forested areas with small construction area The data used for this research was obtained from satellite images that demonstrating the rate of deforestation in Ilorin for about 30 years. The stage performed to collect the image information was Image Pre-processing. Under image processing, image normalization was conducted employing the histogram matching method. Image sub-setting was also engaged in which the image was clipped to the study area using the extract of mask tool in ArcGIS 10.5.
Image pan-sharpening was utilized to improve the resolution of the multi-spectral images.

Digital Number (DN) to Reflectance Conversion (RC), Image Classification and Feature
Extraction (Train signatures, Image segmentation, Support vector machine classification) were also applied. In order to estimate evapotranspiration and interpolating climatic variables, SEBAL (Surface Energy Balance Algorithm for Land) model was utilized for the ArcGIS 10.5 environment to generate grid maps for climatic variables. Five satellite images were employed for this research. Each satellite image was captured at intervals. The intervals were between 1991-1996, 1997-2001, 2002-2006, 2007-2011 and 2012-2018. The satellite images were obtained from Landsat. The information regarding the extraction methods for satellite image data is presented in Table 1. Descriptive statistics were being used for presentation and summary were mean, frequency distribution tables and bar charts. In order to predict, this study employed the multiple regression analysis (Bender et al., 2007) to assess the effects of deforestation on microclimate by the year 2030.

Result and Discussion
There was a gradual increase towards area covered by bare surface, although there was a decrease by 8.9% in 2003. The gradual increase in the term of bare surface size on the land can be attributed to the increase of land acquisition for agriculture, some lands were left to fallow in order to store the nutrient for the next farming season. The size of construction areas grew rapidly from 8. 62% in 1991-1996, 12.95% in 1997-2001, 13.98% in 2002-2006 and 2007-2011 and 16.82% in 2012-2018 (Table 2 and Figure 2). This is in line with Dias et al., (2015) reported that evapotranspiration will be modified as a result of converting natural vegetation to bare surface and agriculture land. Then, it will manage to speculate the microclimate of the area being studied.   respectively. The Forested surface also suffered a slight increase with 3.61, while grassland and marchland experienced a decrease with percentage with 25 and 26 respectively. This result is suitable with Daramola et al., (2015) reported that more the alteration of forested areas and vegetated surfaces shifting into construction areas and bare surface means the more of the land surface temperature will increase.
In addition, Urban areas become hotter than the rural areas due to such similar changes generating a distinctive area with warmer temperatures in the landscape (USEPA, 2017). Therefore, the heat tends to spread to other parts of the city, affecting its microclimate.
Toluwalope Mubo Agaja et al / GEOSI Vol 5 No 3 (2020) 301-317 Vegetation covers serve as carbon sinks, it assisting to reduce excessive warming of the surrounding environment (Nunes et al., 2020).  Table 3 shows the model employed in predicting the micro climatic variables with the predicted rate of deforestation as the independent variable. As presented in Table 3, the model for predicting Maximum Temperature is given as Y = 0.105x + 29.993, maximum temperature has a predictive increase rate of 0.105 O C per annum. This implies that for each additional forest loss, the maximum temperature increases by 0.105 o C. This result is slightly different from Bright et al., (2017); Alkama & Cescatti (2016); Chapman et al., (2018), that local and regional-scale impacts of tropical deforestation result in warmer surface temperatures and greater variation in temperatures. Furthermore, the model for predicting Precipitation (PPT) is given as Y = -0.005x + 0.608, PPT has a predictive decrease rate of -0.005 mm per annum. Predicting wind speed is given as Y = -0.005x + 3.212: wind speed has predictive decrease rate of -0.005 m/s. This implies that for each additional forest loss, there is a decrease of 0.005 m/s in wind speed. In addition, the model for predicting Relative humidity is given as Y = -0.232x + 78.376, Relative humidity has predictive decrease rate of -0.232 kPa. This means that an addition of forest loss will lead to a decrease rate in relative humidity with -0.232 kPa. Predicting solar output is given as Y = -0.082x + 32.550, solar output has predictive decrease rate of 8%. This implies that there is an 8% decrease in solar output regarding an additional increase in deforestation. Furthermore, the model for predicting evapotranspiration is given as Y = 0.097x + 25.214, evapotranspiration has predictive increase rate of 0.097 mm per annum. This implies that there will be an increase in evapotranspiration rates as a result of an increase (2018) stated that there is a relationship between the local climate and deforestation as pronounced changes were noticed which were as high as 40% -75% loss of the forest and addition temperature increase to above 31 °C and more than 15% reduction in rainfall as a result of more than15% forest loss since 1973 in Southeast Borneo. This occurred as the forested areas have been subjected to an open field. Prevedello et al., (2019) also reported that land surface temperature (LST) might fluctuated due to deforestation or afforestation as open vegetation obtains a higher surface albedo compared to a cluster of trees. Thereby, increasing evapotranspiration (ET) and vagaries in the microclimate of the area being investigated. Also, the opening and withdrawing the canopy are the most pervasive impact upon logging as it rises solar radiation and air flow within under storey and the drop of evapotranspiration leading to an alteration of the forest's microclimate (Hardwick et al., 2015;Jucker et al., 2020;Senior et al., 2018).   Table 4 to the year 2018 (Table 2), forested area is predicted to suffer a reductionby 36.1%, maximum temperature would likely rise by 8.15%, minimum temperature increased by 0.88%. Furthermore, rainfall is predicted to drop by 30.9%, wind speed to drop by 3.65%, relative humidity to decline by 8.6%, solar output to decrease by 3.2% while evapotranspiration is expected to increase by 8.8%.
The implication of these result for maximum and minimum temperature is the increase upon these variables that will spoil human health which leads to illness such as heat waves, meningitis, typhoid, malaria among others. This result is suitable towards Daramola et al., (2015) that stated in Ilorin, the forest have been put towards to construction areas and grassland in most areas between 1972-2014 in Ilorin. Temperature up surge might also affected agricultural activities leading to a decrease of crop yield. Hence, decrease in yield of crops means disturbing food security within the area. Trees should be planted in the area to reduce temperature and people could make benefit of it as the shade upon afternoon heat, thus it would help people in the sense physiological comfort. Temperature increase might also altered rainfall season in the area. There is an increase in temperature variation due to forest loss. This tends to lead to an increase towards mean and maximum upon air temperature compared to carbon dioxide emissions from land-use change that resulting to significant amount of heat (Alkama & Cescatti, 2016).
Furthermore, the loss of shade may result inheat index escalation to over 9 °C. This occurs as forests environment, evapotranspiration reduces sensible heat and means a much more frigid environment could be created (Bright et al., 2017;Ellison et al., 2017;Wolff et al., 2018). The microclimate has been greatly affected, since high temperature changes due to land use patternis shifting. Land surface temperature analysis shows an upsurge in urban land area temperature was due to reduction of forested areas and grasslands. The decrease will possibly disturb water security which involves accessibility, availability and quality in the area. Decrease of rainfall affects the water table constribution towards residents within the area.
Decrease in wind speed may interrupting pollination in the area that leading to yield of crops decline. In term of human health, the drop of wind speed will reduce the spread of airborne diseases, means this proposes a positive effect on human health. Decrease in relative humidity can affect human skin, namely dryness of the skin. It could also affect crops in the area. Evapotranspiration increase would manage to increase the rainfall that may consequence in flooding which threatens life and properties. Hence, a crucial climate change by 2030 could be avoided (Fritts, 2018;Milman, 2018). This happens, since carbon mitigation can be achieved where there is vast proportion of forest cover and this would avoid the release of carbon dioxide as well as harnessing atmospheric carbon by the growing forest.

Conclusion
The study concludes that deforestation greatly influences the microclimate of Ilorin and occurs due to human's anthropogenic activities. These human activities are related to the conversion of land from forest to agricultural land. Furthermore, the use of agricultural land that is not under regulations will increase bare land. Deforestation has also led to climate change. Thereby, this study recommends public awareness and provide education for people to recognize and engage manners to avert and reduce the adverse environmental effect associated with deforestation and take appropriate actions to deal with it. Laws regulations should be enacted and enforced by government to reduce the nature and to limit extent of the destruction of the forest. Penalties should also be put in place for violators.