Viewpoint pubs.acs.org/est
India’s Rare Inland Mangroves Deserve Protection Pratiksha Patel Department of Botany, Gujarat University, Ahmedabad, India
Govindasamy Agoramoorthy* College of Environmental Sciences, Tajen University, Yanpu, Pingtung 907, Taiwan, and Gujarat Institute of Desert Ecology, India suggested that the inland mangroves of Barbuda and Inagua were connected by seawater flowing under the tidal influence of the karst topography through oceanic holes located far inland.3 Similarly in the Caribbean, these mangroves on limestone islands are supported by such inland saline ponds, which in turn are connected with the ocean through submarine caves. Since the viviparous mangrove propagules are dispersed through seawater, the locations seem to reflect former sea level. Irrespective of their geographical locations, these mangroves occur mostly in limestone topography cut off from the open ocean due to geological barrier or sea-level changes.4 In India’s Kachchh district of Gujarat state, an ecologically peculiar patch of inland mangrove exists that too is in a totally land-locked position without any surface connection to sea. It is located at the Shravan Kavadia templea renowned Hindu pilgrimage site associated with the mythological character Shravan Kumar from the epic Ramayana. The mangroves stand has significance in the folklore and thus logging, grazing, or collection of firewood from the inland mangrove patch is considered religiously inauspicious by the villagers. It is 80 km far inland from the nearest coastal belt of the Gulf of Kachchh and 150 km from the Arabian Sea and is located in the eastern part of Bannia raised mud flat lying between the Great Rann of Kachchh to the north and Kachchh mainland to the south. The site faces harsh weather conditions, from 10 °C in January to 49 °C in May−June with low and erratic rainfall (annual average 317 mm). The survival of an inland mangrove patch in the water-scarce highly saline arid zone where even xerophytes sparsely grow is indeed an environmental mystery. The Kachchh region is geologically remarkable, and over two millennia ago the Rann of Kachchh was a shallow sea. Due to the tectonic uplifts, the Rann started to dry up slowly.5 As a result, it appears that the mangroves patch along this shoreline became land-locked and therefore belong to an ancient gene pool. The Shravan Kavadia mangrove stand comprises mainly Avicennia marina spreading across an area of 0.7 ha with tree heights reaching up to 15 m. Two decades ago, there were 60 adult trees in a dense patch and unfortunately half were destroyed during the 1998 cyclone. Although the Gujarat state’s forest department has partially fenced the area, there is no manpower assigned to protect the remaining trees regularly. During a recent visit, we have seen many old trees infested with wood boring insects (Figure 1). Besides, the habitat is being
T
ropical and subtropical mangrove forests harbor a unique community of trees that thrive in the salty environment dividing the land and ocean. India’s major concentrations of mangroves occur along the coastal areas of West Bengal (46.39%), Gujarat (22.55%), and Andaman-Nicobar islands (13.26%).1 India’s coastal mangrove greenbelts have received considerable conservation attention in the wake of the devastating 2004 Indian Ocean tsunami. However, very little is known on the occurrence, status, and conservation significance of the often-ignored inland mangroves. What are inland mangroves and where do they occur? Mangroves in general are classified based on the magnitude of hydrodynamic exchange, and, for example, the riverine forests receive high freshwater inputs while the fringe forests are flushed regularly by tides. The basin forests are less regularly flushed and scrub forests are often slow in flushing so they tend to have low levels of nutrients.2 In spite of this, there are some unusual mangroves with very poor to no direct connections with seathey are called “inland mangroves”. Only a few cases of surviving inland mangroves far away from sea worldwide have been reported in the scientific literature. They occur either on islands, deltas, and lagoons, or along fringes of water bodies. Some thrive in regions with distinct dry seasons while others have poor connection to the seas. But they all occur in patches in countries such as Australia, Antigua-Barbuda, Bahamas, Guatemala, Indonesia, Mexico, and Pakistan. Scientists have © 2012 American Chemical Society
Published: April 5, 2012 4261
dx.doi.org/10.1021/es301062v | Environ. Sci. Technol. 2012, 46, 4261−4262
Environmental Science & Technology
Viewpoint
Figure 1. Part of the inland mangrove at Shravan Kavadia (Gujarat, India) in better condition a decade ago (left; photo courtesy J. Tiwari) and in degraded state now (right; photo by G. Agoramoorthy).
fast replaced by the invading Prosopis juliflora that depletes the groundwater sources vital for the survival of mangroves. Shravan Kavadia seems to be the only inland mangrove patch that exists in India, therefore it deserves immediate conservation and management attention. In several coastal areas of India, mangrove forests have been successfully restored. So this small patch of mangrove can easily be restored if it receives immediate attention from local government and nongovernment agencies. While restoring the patch, propagation using the existing mangroves as parent material should be adopted to maintain the ancient gene pool. Deliberate introduction of mangrove saplings from other parts of Gujarat, especially Gulf of Kachchh or Gulf of Khambhat should be avoided. There is an urgent need for scientific monitoring of the inland mangrove so that the invasion of the exotic plant Prosopis julif lora and human disturbances can be kept minimal to maximize the restoration of the inland mangroves. The action at local level is critical, therefore villagers and pilgrims should be made aware of the unique ecological significance of the inland mangroves before it is too late.
■
AUTHOR INFORMATION
Corresponding Author
*Phone: +886-916752019; e-mail:
[email protected]. Notes
The authors declare no competing financial interest.
■
REFERENCES
(1) India State of Forest Report; Forest Survey of India, Ministry of Environment and Forests, Government of India, 2009. (2) Lugo, A.; Snedaker, S. The ecology of mangroves. Ann. Rev. Eco. Syst. 1974, 5, 39−64. (3) Lugo, A. The inland mangroves of Inagua. J. Nat. Hist. 1981, 15, 845−852. (4) Ellison, J.; Simmonds, S. Structure and productivity of inland mangrove stands at Lake MacLeod, Western Australia. J. R. Soc. West. Aust. 2003, 86, 25−30. (5) Biswas, S. K. Landscape of Kutch: A morphotectonic analysis. Ind. J. Earth Sci. 1974, 1, 177−190.
4262
dx.doi.org/10.1021/es301062v | Environ. Sci. Technol. 2012, 46, 4261−4262
