National Level Assessment of Mangrove Forest Cover in Pakistan

Abstract

Mangroves ecosystems consist of inter tidal flora and fauna found in the tropical and subtropical regions of the world. Mangroves forest is a collection of halophytic trees, shrubs, and other plants receiving inputs from regular tidal flushing and from freshwater streams and rivers. A global reduction of 25 % mangroves' area has been observed since 1980 and it is categorized as one of to the most threatened and vulnerable ecosystems of the world. Forest resources in Pakistan are being deteriorating both quantitatively and qualitatively due to anthropogenic activities, climatic v and loose institutional management. According to the FAO (2007), extent of forest cover of Pakistan in 2005 is 1,902,000 ha, which is 2.5% of its total land area. Annual change rate during 2000-2005 was-2.1% which is highest among all the countries in Asia. The Indus delta region contains the world's fifth-largest mangrove forest which provides a range of important ecosystem services, including coastal stabilisation, primary production and provision of nursery habitat for marine fish. Given their ecological importance in coastal settings, mangroves receive special attention in the assessment of conservation efforts and sustainable coastal developments. Coastline of Pakistan is 1050km long shared by the provinces, Sind (350km) and Baluchistan (700 km). The coastline, with typical arid subtropical climate, possesses five significant sites that are blessed with mangroves. In the Sindh province, mangroves are found in the Indus Delta and Sandspit. The Indus Delta is host to the most extensive mangroves areas and extends from Korangi Creek in the West to Sir Creek in the East, whereas Sandspit is a small locality in the West of Karachi city. In the Balochistan province, mangroves are located at three sites, Miani Hor, Kalmat Khor and Jiwani.

Evaluating Combinations of Sentinel-2 Data and Machine-Learning Algorithms for Mangrove Mapping in West Africa

“…Most of these studies use optical satellite data, especially Landsat, due to longer temporal coverage and ease of data accessibility. With the availability of active satellite data, many studies are increasingly utilizing radar data from sensors including the Advanced Land Observing Satellite (ALOS) based Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR), RADARSAT-2, the Shuttle Radar Topography Mission (SRTM), for quantifying mangrove extent and other biophysical characteristics [15,[58][59][60][61][62][63][64][65]. While availability of Sentinel-1 from the European Space Agency (ESA) data has shown promise for continued use of radar data in mangrove mapping in the coming years, historical land cover mapping and monitoring often need to rely solely on optical remote sensing data due to the lack of radar data before the 1990s.…”

A Synthesis of Spatial Forest Assessment Studies Using Remote Sensing Data and Techniques in Pakistan

“…The total mangrove forest cover assessed through the GMW data set collectively in these sites was 680 km 2 in 2016. The first national-scale study, by Abbas et al [81], used NN and rule-based methods in OBIA to map mangrove forests using ALOS AVNIR-2 for 2009. The total mangrove forest cover for all these sites was 981.3 km 2 in this study.…”

“…Overall accuracies of 99.96%, 99.9%, 99.53%, 99.96%, 99.93%, and 99.68% with kappa coefficient values of 0.9995, 0.9996, 0.9935, 0.9994, 0.9985, and 0.9945 were calculated for the years 1979, 1992, 1998, 2000, 2006, and 2009, respectively. Similarly, Abbas et al [102] used overall accuracy and the kappa coefficient to assess the accuracy of the national-level mapping of mangrove forests in Pakistan. Two hundred fifty ground validation points were used to assess the accuracy of the classified map.…”

“…However, they did not mention the observed accuracy values (user's and producer's accuracies) and only mentioned overall accuracies of 79.2% and 81.1% for 2001 and 2009. Abbas et al [81] used the OBIA method to map mangrove forests in Pakistan and assessed the accuracy of their classified image using overall accuracy and kappa coefficient. In this national-scale study, they found overall accuracies of 80.2%, 84.6%, 80.5%, 78.9%, and 83.7%, and kappa coefficients of 0.71, 0.74, 0.76, 0.69, and 0.73 for the study locations of Indus delta, Sandspit, Kalmat Khor, Miani hor, and Jiwini, respectively.…”

“…In this forest ecoregion, eight studies were conducted [32,74,76,77,81,83,99,102]. The studies reported an increase in the mangroves' forest area in the coastal belt of Pakistan and the Indus delta.…”