KARACHI, Nov 9: The mangrove forests of the Indus Delta are facing great stress, but owing to massive plantation carried out by the government as well as non-governmental organisations, the mangrove cover that was shrinking rapidly till the mid-1980s has begun taking a U-turn, says a report.
The mangroves grow usually in river deltaic regions where sweet water mixes with saline seawater. These forests act as nurseries to numerous commercially important marine species, helping not only the fishermen community to earn a livelihood, but also the country to earn foreign exchange. The extensively developed root system of the mangrove trees fortifies the coast line and acts as a barrier against coastal erosion.
The single largest threat to the mangroves is the continuous reduction in the amount of sweet water brought by the Indus river.
It had been decreasing over the years owing to the construction of reservoirs and barrages upstream so that the water could be used for irrigation as well as electricity generation.
Owing to lesser water coming down to the delta, the seawater is intruding on land and could be seen up to the Thatta-Sujawal bridge, nearly 100 kilometres upstream from the Arabian sea. The seawater invasion has not only affected the subsoil aquifers in the coastal areas, a majority of which had become saline, but had also rendered large tracks of agricultural lands barren in the coastal districts of Thatta and Badin, financially crippling the agriculturist community in the area.
Pakistan has a coast of over 990 kilometres, of which 230km are in Sindh and 760km in Balochistan. However, over 95 per cent of the mangrove forests are in Sindh — in the Indus Delta — and only around 5 per cent are in Balochistan — Miani Hor (Sonmiani Bay), Kalmat Hor and Jiwani Lagoon.
In Sindh the mangroves are spread over 107,640 hectares – 1,160 hectares (11.60 square kilometers) in Karachi harbour and 106,480 (1,065 square kilometers) in the Indus delta.
A report prepared by the Space and Upper Atmosphere Research Commission says that of the 1,160 hectares of mangroves in the harbour, 630 hectares were dense forest while 385 hectares and 145 hectares were medium dense and sparse forest, respectively. Whereas in the Indus delta, of the total of 106,480 hectares of mangroves 25,320 hectares were dense while 34,700 hectares and 46,460 hectares were medium dense and sparse, respectively.The Indus delta mangrove forest is the second largest mangrove ecosystem in the subtropics – the largest such mangrove forest being the Sunderbans, which straddle the India-Bangladesh border along the Bay of Bengal.
The mangroves survive in the inter-tidal zone in the deltas where the silt-infested fresh water is brought in by the river and it mixes with the saline seawater. Besides the less quantity of fresh water being brought in by the Indus, the threats to the mangrove include cutting for timber, fuel and grazing by livestock.
A report prepared by the a technical adviser to the Sindh Coastal Development Authority and a former Sindh forest secretary Shams-ul-Haq Memon, who had presented this report at a regional meeting organised by the IUCN in India in the last week of August, says that historical records show that the mangrove cover in the Indus delta in the 1930s — that is before the manipulation with the Indus river water had begun — was 600,000 hectares which witnessed a rapid decline in the next seven decades — when numerous manmade interventions were done by constructing reservoirs and barrages — and it shrunk to around 86,000 hectares by 2005. However, from there on the tide seems to have turned and with massive plantations and conservation efforts with the help of community and NGOs, the mangrove covers started to increase and had crossed over 100,000 hectares mark till recently.
While the data regarding the mangrove forest cover in the Indus Delta by and large remains the same, there seems to be a difference of opinion among different stakeholders — the Sindh Forest Department, Sindh Coastal Development Authority (both government organisations) and the IUCN (a non-governmental organisation). The data remains the same that in 2005 there were around 86,000 hectares and since then around 40,000 hectares had been planted. So by now these should have been 126,000 hectares, but they are just 107,000 hectares, leaving a figure of around 20,000 hectares unaccounted for.
SFD coastal areas conservator Riaz Wagan says that the satellite imagery showing 107,000 hectares could not totally be accurate as it might not be picking up smaller plants planted a couple of years back. Though he agrees that some mangroves might have been affected by the degradation causes, less fresh water supply, cutting for fuel and grazing, etc, he insists that the mangrove cover is greater than what the imageries are showing and it could be confirmed by field surveys.
SCDA’s Mr Memon suggests that the increase in mangrove coverage from 86,000 in 2005 to around 107,000 hectares in 2009/10 was due to massive plantations by the government as well as non governmental organisations, and wider spread of awareness among the coastal communities who try to protect the mangroves. He also agrees that if the causes of degradation like less fresh water, grazing and cutting for fuel etc were checked and plantation drives continue, the mangrove cover will increase at a faster pace.
Giving his opinion on the missing 20,000 hectares, IUCN national resources management chief Ghulam Qadir Shah says that the survival rate of all plantations might not have been 100 per cent. So while 40,000 hectares had been planted, not all had probably survived. Or maybe, the new plantations had survived while the mangroves in other areas had been destroyed. The other causes could be a shortage of sweet water, cutting and grazing which could collectively be contributing to the missing 20,000 hectares.
He said new plantation drives were a must not only to sustain but to increase the mangrove forests; if that was not done, the existing mangrove cover would shrink quickly.