By Ranjan Panda*
Although mangroves make up less than one percent of all tropical forests worldwide, their contribution to mitigation of climate change is huge. Unfortunately, however, they are facing the fastest ever rate of destruction. Any further delay in corrective action to protect and conserve mangrove ecosystems would not only mean huge loss of livelihood of a large number of coastal communities in the developing world, but also make us more vulnerable to devastations caused by the increasing number of cyclones.
A just published report on mangroves by the United Nations Environment Programme (UNEP) titled, “The important of mangroves to people: A call to Action” reinforces this point.
Several research studies have now conclusively established that mangroves act as significant carbon storage systems, sequestering vast amounts of carbon – about 1,000 tonnes of carbon per hectare – over thousands of years. With continuing deforestation, this coastal “blue carbon” is at risk of being released back into the atmosphere when mangroves are cut down and converted into shrimp ponds or replaced by hotels, ports or used as landfill, says this report.
More importantly, emissions from deforestation of the same mangroves that act as one of the best carbon sinks make up nearly one-fifth of all global emissions due to deforestation. In fact, mangroves continue to be lost at a rate 3-5 times faster than global deforestation rates. The report estimates economic damages on account of mangrove destruction at about US$ 6-42 billion annually.
Actually, the losses to the communities dependent on mangrove ecosystems are much more than anyone can estimate. Tropical mangroves around the world connect our land and its people with the sea, providing millions with food, clean water, raw materials and resilience against future climate change impact, including increasing storm intensity and sea level rise.
Together with coral reefs, seagrass meadows and intertidal mudflats and marshes, these complex interconnected ecosystems are home to a spectacular range of visiting and resident species of birds, mammals, invertebrates and fish, all of which help maintain the ecological functioning of mangroves. In turn, this rich mosaic of biodiversity supports people through fisheries, tourism and cultural heritage, the report points out in its introduction.
Gone in 100 years?
It is estimated that people dependent on mangrove ecosystems may be deprived of the services in just about 100 years making life of these dependent communities miserable. This means the world may lose all its vital mangrove ecosystems in just a century’s time, if the current rate of degradation continues.
It could actually be faster than that. This loss would result in serious consequences for the local people in the form of degraded economies, impoverished livelihoods, declining human security and therefore poor quality of life for the already vulnerable coastal communities in developing countries.
While a prosperous coastal community is directly dependent on a healthy mangrove ecosystem, loss of mangroves would mean disastrous consequences to the nation and the globe as a whole. The UNEP reports that over 100 million people around the world live within 10 kilometres of large mangrove forests, benefiting from a variety of goods and services such as fisheries and forest products, clean water and protection against erosion and extreme weather events. These ecosystem services are worth an estimated US$ 33-57,000 per hectare per year to the economies of developing countries with mangroves.
However, mangroves are one of the most undervalued ecosystems in the world. There are very few studies available on the small systems and hence it is virtually impossible to quantify the value of ecosystem services of all the mangrove forests. My own view is that it is not necessary to quantify each and every ecosystem service. The fact that millions of people and other species depend on mangroves calls for our urgent attention. As humans, even if we want to become selfish and count only our own benefits, the experience of recent cyclones must stir our minds further to know the important role mangroves play in managing cyclones, sea surges and related disasters. To understand this, we need to know the basic composition of mangrove forests.
Mangroves, our wall against disasters
Uniquely positioned at the dynamic interface of land and sea, mangroves form the foundation of a highly productive and biologically rich ecosystem which provides a home and feeding ground for a wide range of species, many of which are endangered. The complex network of mangrove roots can help reduce wave energy, thus limiting erosion and shielding coastal communities from the destructive forces of tropical storms.
Mangroves offer natural and low-cost risk reduction mechanisms against rising sea levels and changes in the frequency and intensity of storms.
The UNEP report, citing studies already done on this, says that mangroves can rapidly reduce wave energy as they pass through the trees. The extent of reduction in the height of relatively small waves due to this natural barrier has been found to be anywhere in the range of 13% to 66% over a 100 m wide mangrove belt. The effectiveness is largely dependent on the density of the mangrove vegetation. Waves passing through dense aerial roots and tree canopies will be reduced most effectively. The provision of shelter by mangroves is not only important for people on land, but also for those operating at sea.
In case of storm surges, the report suggests – again citing studies – that mangroves can reduce storm surge levels by up to 50 cm per km width of mangroves. While large areas of mangroves are needed to significantly reduce peak water levels, even relatively small changes in water depth may result in large areas being saved from flooding, particularly in areas of low relief that are typical for mangroves.
The report further finds out that coastal forests such as mangroves cannot completely stop a tsunami, but they can absorb some of the energy of the flowing water and thus reduce the force of the impact, saving lives and reducing damage to property. Mangrove trees can also disrupt the huge flows of water as the wave recedes and block property and people from being swept back to the sea.
The Odisha Case
The UNEP report has a case study on the Bhitarkanika forests and mentions that this protected mangrove area provides important ecosystem services to dependent communities, and is also home to 300 plant species and 263 species of birds, including five different species of kingfishers of which two (Brown-winged and Ruddy Kingfisher) are globally threatened. In addition, it provides a home for the globally threatened Olive Ridley Turtles, the Saltwater Crocodiles and the Irrawaddy Dolphins.
Studies on the role of Bhitarkanika Mangrove Ecosystem in protecting villagers against the 1999 super cyclone have found out that villages which were protected by mangrove forests suffered less than the ones which had no protection from these unique forests. In fact, the report comes out with a very interesting finding that compares the loss suffered by villages with embankments with villages having mangrove forests.
A study that was referred to by the report has found out the following: The loss incurred per household was greatest (US$ 154) in the village, which was surrounded by the embankment (as a result of the embankment breaching and the flood water being slow to recede, increasing damage to crops), followed by the village that had neither mangrove nor an embankment (US$ 44).
The village which was protected by mangrove forests incurred the lowest loss per household (US$ 33). Embankments near mangrove forests were not breached while those further away were breached at a number of places, implying that mangroves may have helped to protect these defences. The local people were aware of and appreciated the functions performed by the mangrove forests in protecting their lives and property from cyclones and were willing to cooperate with the forest department in mangrove restoration.
In fact, the Odisha coast has lost a huge chunk of its mangrove forests. Since the Bay of Bengal is increasingly vulnerable to cyclones and storms, future disasters will be much more fatal and devastating unless we take prompt and massive measures to restore, plant and conserve mangrove forests.
Call for Action
Philippines, which was hit by one of the worst typhoons – the Yolanda – in November 2013, has now started a massive effort to revive mangrove forests. It is reported that this country has lost over 50 per cent of its mangroves since 1918. It has now taken up a programme with an investment of over twenty million US Dollars under which it is promoting mangrove replanting, developing greenbelts of mangrove and beach forests as natural protection against storms. India too has been investing in mangrove restoration.
To restore Mangrove Ecosystems, one needs to understand the real causes of their destruction. In 2010, a report of the Global Marine Species Assessment (GMSA) revealed that the shrimp industry accounted for almost 38 per cent of the destruction of mangrove forests globally. It reported that at least 26 per cent of global mangrove forests have been cleared for fuel wood and timber production.
In India, as per this report, 40% of the country’s mangroves have already been converted to agricultural land or lost to urban sprawl. In fact, this report apprehended a faster rate of destruction of the mangroves in the coming days and said that at the current rate, mangroves may vanish by the end of this century as against the 100 years estimated in the UNEP report.
The loss rate of mangroves has accelerated since the 1980s and the future looks really grim. Roads, infrastructure, tourism industry, ports and embankment walls have come up at a massive rate in the last few decades. The pace of such ‘mangrove destructive development’ is going to be faster in coming years leading thereby causing direct destruction through deforestation as well as indirect destruction of mangroves through pollution.
The UNEP report suggest some measures for restoration of mangroves and their protection – both through direct field action and policy intervention and is hopeful that time is still there to turn the tide and avert the considerable ecological, social and economic costs now, and in the future. I would say, we need to act now or perish as cyclones and storms increase in their frequency and intensity.
*The author is a Sambalpur based water rights activist and Convenor of Water Initiatives Odisha (WIO)