Abstract
The unchecked and unplanned expansion of urban areas has led to the conversion of millions of green areas to gray areas. The recent urban growth patterns of Pakistan’s metropolitan twin cities, Islamabad and Rawalpindi, is a matter of concern for the surrounding green areas. The present study aimed to categorize and quantify the land-use and land-cover change (LULCC) patterns and the corresponding impacts on the forest carbon dynamics around Islamabad and Rawalpindi. Multispectral satellite images for the year 1990 (Landsat 5 TM) and 2020 (Landsat 8 OLI) were used to determine, quantify, and compare the LULCC inside and around the twin metropolitan cities. Field inventory surveys in the reserved forests of Rawalpindi and Islamabad were also conducted to determine the amount of stored carbon in these forests. Our results showed an accelerated annual urban expansion (i.e., an increase in the built-up area) of 16.49% and 26.72% in Rawalpindi and Islamabad, respectively, during the study period. Similarly, the amount of barren land and agricultural land was reduced at an annual rate of 2.08% and 2.18%, respectively, in Rawalpindi and 0.25% and 1.04% in Islamabad. A reduction in the area of barren mountains also occurred at an annual of 2.26% in Islamabad, while it increased by 4.16% in Rawalpindi. The amount of carbon stored in the reserved forests of Islamabad stood at 139.17 ± 12.15 Mg C/ha while that of Rawalpindi was 110.4 ± 13.79 Mg C/ha. In addition, total stored forest carbon was found to have decreased from 544.70 Gg C to 218.05 Gg C in Rawalpindi, while in Islamabad it increased from 2779.64 Gg C to 3548.16 Gg C. Investment in ecological urban planning, sustainable cities, and appropriate land-use planning is recommended to curb the degradation and conversion of the surrounding green areas of Rawalpindi and Islamabad.
Highlights
In recent decades, the number of people moving to urban cities from rural areas has increased exponentially
Our results showed that the twin cities have experienced an enormous expansion of urban growth during the past three decades
In 1990, the built-up area in Islamabad was 3.33% (3018.42 ha) of its total area, which expanded to 30.01% by 2020 (27,218.06 ha) (Table 3)
Summary
The number of people moving to urban cities from rural areas has increased exponentially. In Asia, the urbanization rate is 6.6% for Nepal, 5.3% for Bangladesh, 4.4% for Pakistan, 2.9% for India, and 2.2% for Sri Lanka The rates for these developing countries are higher compared to other Asian countries and to the rest of the world [1,2,3]. This upsurge in the global urban population results from economic opportunities, infrastructure development, and political and social stability [4]. These growth patterns exhibit regional and continental variations, factors that cause or accelerate urban sprawl remain the same [5]. These environmental, socioeconomic, cultural, and religious factors play an important role in urban development across the globe [6]
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