1. Department of City and Regional Planning, Lahore College for Women University, Lahore, Pakistan
2. College of Earth and Environmental Sciences, University of the Punjab, Lahore, Pakistan <
The author(s) declared that no grants were involved in supporting this work.
The present study aims to evaluate the evolution of vegetation and land-cover practices particularly changes in tree cover, shrubs and mixed vegetation during 1994 to 2014. The rapid urbanization in Lahore has now converted the city into a second largest metropolitan city of the country which, in consequence, is affecting the land cover. Keeping in mind these facts, analyses are performed using calibrated satellite images of the year 1994, 2003 and 2014 in GIS environment coupled with ERDAS Imagine. The study is further divided into two parts; first part illustrates changes in tree cover, shrubs and mixed use areas whereas second part explains the changes in shrubs and tree cover in comparison to the mix use area. It is observed that the shrubs are considerably increased from 7% in 1994 to 52 % in 2014 while the tree cover has drastically decreased from 8% in 1994 to 0.38% in 2014.
How to cite: Saleem, S., and Saleem, S., 2016: Spatial and temporal evolution of vegetation cover in Lahore, Pakistan. Bulletin of Environmental Studies 1(3): 81-86.
Copyright © Saleem & Saleem. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The
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Edited by: Muhammad Arslan (UFZ, Germany)
Reviewed by: Muhammad Mudassar (TrafQuest, UAE) & Muhammnad Arslan (UFZ, Germany)
Published Online: 30/07/2016
Urbanization is a steady transformation phenomenon in which rural settlements such as villages and small towns are turned into more urbanized settlements as a result of population expansion. In principle, urbanization is controlled by land-based practices; nevertheless it is also influenced by industrialization, commercialization and construction of public facilities due to increasing population demands. It has been revealed that the practices may increase the vegetation cover at global scales due to disturbance of climate processes by high CO2 production and increasing temperatures (Vicente-Serrano et al., 2004).
After independence in 1947, urban development in Lahore was rarely observed despite of the fact that large number of migrants moved from east Punjab (India) to Lahore resulting in population increase (Qadeer, 1983). Lack of developmental knowledge and practices lead to disorganized and un-settled living conditions in the city. The style of living remained same until the city witnessed, almost 3 decades ago, a tremendous spatial growth especially in the old walled region; hence, making it a historical urban city.
Rationale of the study: The major problems of urban settlements in Lahore are disorganized growth pattern with unplanned developmental projects; and to cope with this outgrowth, agricultural land is now being encroached. Along with the population growth, socio-economic requirements are also soaring which in turn is ultimately creating a pressure on land cover. This pressure is the elemental cause of unplanned changes in land use and land cover (LULC) that are getting uncontrolled along with (Seto, 2002).
For the monitoring and management of urban sprawl and urban land use, reliable source of data is of key importance; to save up on time, the sources should be efficient enough that the data can be fetched out in short time. As many of the conventional technological methods of field surveys were time consuming; application of GIS and Remote Sensing (RS) have helped researchers to do comprehensive spatio-temporal analysis in a relatively shorter time (Lo and Yang, 2002). The application of GIS and RS ensures the authenticity, accuracy, flexibility and ease of collection, storage and analysis of essential digital data for detection, and timely monitoring of spatial features at larger scale (Zsuzsanna, 2005; Wu, 2006).
Vegetation cover is an important feature in urban development and therefore each development project, within or outside the city, should not compromise the changes in vegetation cover significantly. The NDVI is an index of the state of biomass within an area. Hence, the NDVI is the most popular indices used to display extent of greenness estimate of an area. Kriegler, et al., (1969) was the first to propose NDVI which is calculated from two bands of multispectral SRS data.
For the purpose of land use planning by the experts, and decision making in urban and environmental planning for a sustainable ecological setup, in depth knowledge of urban land cover and the areal extent distribution data is an essential requirement (Stefanov, 2001 and Fan et al., 2007). The researchers now-a-days are interested in the LULC at micro and macro scale. Additionally, LULC can be caused either by natural or anthropogenic modifications which has resulted in great loss of entities having biological importance i.e., loss of agricultural land, biodiversity, etc. The impact is ecological (geo-environmental) as well, ranging from global warming to raised threat of natural disasters and flooding (Dwivedi et al., 2005).
The study is conducted in Lahore (Pakistan), largest city in Punjab province and second largest city district of Pakistan with the rapid urbanization (transforming the city form metropolitan city to megalopolis). The city is located between 31.25 and 31. 71 North latitude, and 74.16 and 74. 65 East longitude. India lies on the east of Lahore, Sheikhupura on the North West, Kasur on the south and River Ravi flows in the north (GOP, 2000; Riaz, 2011). Lahore is situated 213 meters above sea level with an area of 1,772 km2 (GOP, 2002). The total population of Lahore during 1998 census period was 5,143,495 while, in 2009, Punjab development statistics showed that this number has been increased to 8,462,000 (GOP, 2009) (Figure 1).
Materials and Methods
Landsat data of different years from the US GLOVIS website was retrieved for the spatial and temporal analysis of vegetation. The images, having path 149 & row 38, were extracted for the year 1994, 2003 and 2014 while the choice of years was based on the availability of data during the same month. The extraction of files for each year appeared to have 7, 9 and 13 bands, respectively. The layer stacking of the bands was performed in ERDAS Imagine 2010 environment. The resulting output image was a multi-band geo (.tiff) that can be used in further planning of the area and in statistical evaluations.
Three Landsat images were analyzed and unsupervised classification was performed with the option of NDVI with the input layer stacking in ERDAS Imagine. The output NDVI file was opened in the ArcMap v10.1 and was reclassified using the spatial analyst tool; while break values of the shrubs, tree cover, and mixed use vegetation were added in reclassify dialogue box. The NDVI value ranged between –1 to +1; where +1 denotes a high vegetal cover and –1 signifies non-vegetated areas.
Results and Discussion
In terms of the area covered by different types of vegetation, urbanization is observed to be beneficial for shrubs as it showed a boosting trend with land consumption of 39 km2 (i.e., 7.45%) in 1994 and 270 km2 (i.e., 52.49%) in 2014. However, contradictory outcomes are revealed for tree cover as a drastic downfall was observed from 43 km2 (8.22%; in 1994) to 2 km2 (0.38%) in 2014. On the other hand, mixed land use occupied 441 km2 in 1994 (i.e., 85% of total land cover), which was increased up to 474 km2 (i.e., 90%) of total land cover in 2003; and then again decreased to 248 km2 (i.e., 47.9%) in 2014 (Table 1).
Analysis on the Landsat data of Lahore depicts that, in 1994, most of the land was under mixed use followed by vegetation and least covered with shrubs (Figure 2a). However, the scenario changed quite steadily as the prevalence of shrubs resulted into the decrease of vegetation (Figure 2b). The vegetation pattern in 2014 is contrary to the vegetation pattern in 1994 where maximum of the land can be seen covered with shrubs and least or nominal with the vegetation cover (Figure 2c).
More precisely, relative proportion of the shrubs increased by 86.25% during the study period; as the percentage was 11% in 1994 while in 2003 and 2014, the percentage was 9% and 80% respectively (Fig.3a). On the other hand, the tree cover data depicts a decrease of vegetation by 95.39%; as the relative percentage was 65% in 1994 while approximately 32% and 3% of percentage reduction is observed in 2003 and 2014, respectively (Fig. 3b). The data of mixed use vegetation illustrate the reduction in vegetation by 42.11%; as the percentage was 38% in 1994, while in 2003 it increased up to 40% while reduced to 22% again in 2014 (Fig. 3c). this trend show a meandering variation from a smooth on-going increase to a drastic downfall in its abundance on land. The mixed use such as orchards, bamboo, palms etc. has a natural ecosystem succession process that went on smoothly till the early 21st century. The reason behind this variating trend was studied and explored that the migration of people from smaller cities especially in search of job opportunities and most importantly from disaster prone areas towards safer larger cities put pressure on urban areas for which the vegetation/ flora around the roads were cut in order to widen up roads to ensure the easy movement of traffic. The growing population put serious stress on the land and consequently the flora has been ignored to house growing population on the limited land.
Figure 4 shows an overall temporal trend of different categories under the consideration of this study. It was observed that Shrubs have markedly increased over two decades ranging from 7% in 1994 to 51.72% in 2014. Tree cover/greenery has shown a completely inverse trend from shrubs that have decreased steadily from 8% in 1994 to 0.38% in 2014. Mixed use land cover has been the odd one out which have been struggling with ups and down in the prevalence; as in 1994 the proportion of mixed land uses was 85% slightly went on increasing in 2003 and then showed a drastic downfall (>50%) in 2014.
The results obtained in the present study coincide with the evolution observed at the same level by Shirazi et al., (2009); which reported the reduction of vegetation cover from 645 km2 (36%) in 1992 to 249 km2 (14%) in 2009 in Lahore. The study further predicted, based on local government practices, that the vegetation cover may continue the decreasing trend in upcoming years, which can be seen in the current study, i.e., 0.38% in 2014. Besides, contradiction is observed with the findings of Riaz, (2013) who reported the increase of vegetation cover in Lahore by 68% till 2009 irrespective of reduction in vegetation/agricultural land due to its consequent effects. The study inferred that there is no change in agricultural land use which is completely negating the outcomes of present study. The study carried on by Riaz (2013) has contradiction in its own statements, on one side the researcher is clarifying that the green color in the maps produced is showing no change in agricultural land use while on the other side the researcher is giving a contradictory statement by concluding that the agricultural land has been decreased significantly since 1972 and the urban area is increased tremendously. The green area is kept constant and the urban expansion above it is showed which cannot be justified as the development is been done at the expense of vegetation i.e vegetation loss. Moreover, vegetation/ green area is not constant it tends to decrease as a result of urban area expansion.
In addition, Raza et al., (2016) performed spatio-temporal monitoring during 1976 to 2014 using Landsat satellite images for urban sprawl of Sheikhupura (Pakistan). The results illustrated that the high density urban area has grown during 2000 to 2014 which has drastically influenced the fertile agricultural lands due to the industrial progress in the city. The findings are parallel with the present study which established similar concepts. Moreover, as Sheikhupura is being considered as the territory of Lahore due to rapid urban growth, the results can be compared with these findings accordingly. It is estimated that increasing urbanization will increase the area under cities up to 2.5 times till the year 2030 by utilizing habitable land. Pakistan being an agriculture country, development projects without sustainable plantings may encroach the agricultural lands significantly.
In a nut shell, study reveals significant variations in vegetation cover in a notable fashion where relative percentage of shrubs has increased over the years while tree cover is being decreased significantly. Urban development proved to be as cherishing the shrubs prevalence abundantly and cutting down the abundance of tree cover drastically due to human encroachment. The study provides an updated view of changes in vegetation and land cover which may help detecting various problems related to urban environment. It is therefore required to make a joint strategy for the spatial arrangement of these urbanites. Further research is recommended on different land use/land cover patterns of Lahore particularly focusing on to analyze the loss in area under natural vegetation and agricultural. Similarly, the role of urban expansion towards decreasing agricultural land use may also be emphasized. Additionally, similar studies can be done with nominal time intervals so that the settings of urban spatial patterns may be revealed towards better planning projects.
Compliance with ethical standards
Conflict of Interest
The authors declare that they have no conflict of interests.
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