Remote Sensing of Mangrove Ecosystems: A Review

Abstract

Mangrove ecosystems dominate the coastal wetlands of tropical and subtropical regions throughout the world. They provide various ecological and economical ecosystem services contributing to coastal erosion protection, water filtration, provision of areas for fish and shrimp breeding, provision of building material and medicinal ingredients, and the attraction of tourists, amongst many other factors. At the same time, mangroves belong to the most threatened and vulnerable ecosystems worldwide and experienced a dramatic decline during the last half century. International programs, such as the Ramsar Convention on Wetlands or the Kyoto Protocol, underscore the importance of immediate protection measures and conservation activities to prevent the further loss of mangroves. In this context, remote sensing is the tool of choice to provide spatio-temporal information on mangrove ecosystem distribution, species differentiation, health status, and ongoing changes of mangrove populations. Such studies can be based on various sensors, ranging from aerial photography to high-and medium-resolution optical imagery and from hyperspectral data to active microwave (SAR) data. Remote-sensing techniques have demonstrated a high potential to detect, identify, map, and monitor mangrove conditions and changes during the last two decades, which is reflected by the large number of scientific papers published on this topic. To our knowledge, a recent review paper on the remote sensing of mangroves does not exist, although mangrove ecosystems have become the focus of attention in the context of current climate change and discussions of the OPEN ACCESSRemote Sens. 2011, 3 879 services provided by these ecosystems. Also, climate change-related remote-sensing studies in coastal zones have increased drastically in recent years. The aim of this review paper is to provide a comprehensive overview and sound summary of all of the work undertaken, addressing the variety of remotely sensed data applied for mangrove ecosystem mapping, as well as the numerous methods and techniques used for data analyses, and to further discuss their potential and limitations.

Ecosystem-Wide Impacts of Deforestation in Mangroves: The Urabá Gulf (Colombian Caribbean) Case Study

“…With 18% of the region's mangrove cover, deforestation rate in this country (1.1 and 0.6%) exceeded the South American average (0.69 and 0.18%) in estimates for 1980-1990 and 2000-2005. These figures may be more variable and dramatic at a subcountry level, bearing in mind that coarse-scale inventories using satellite imagery tend to overestimate mangrove cover due to low spatial resolution and heavy cloud cover (as observed in many areas of the Pacific coast and the Urabá region in the Caribbean coast) [14].…”

Mangroves and people: Lessons from a history of use and abuse in four Latin American countries

“…Significant differences between each country's estimates are apparent. These discrepancies in part reflect the difficulties in arriving at accurate estimates through mapping (Heumann, 2011;Kuenzer et al, 2011). By 1999 it was suggested that certain Latin American countries had lost up to 40% of their total mangrove area (Lacerda and Schaeffer-Novelli, 1999).…”

Earth observation satellite sensors for biodiversity monitoring: potentials and bottlenecks

“…Reviews on the remote sensing of other forest ecosystems were provided by Malingreau (1992). Reviews on the remote sensing of coastal mangrove ecosystems have been published by Kuenzer et al (2011) and Blasco et al (1998). Rundquist, Narumalani, and Narayanan (2001), Henderson and Lewis (2008), Lawler (2001), and Kuenzer and Knauer (2013) published overarching articles on remote-sensing techniques for assessing further natural and agricultural wetland ecosystems, and Zhang et al (1997) focused on remote sensing for saltmarsh ecosystems.…”