0195-B1

Sundarbans: Bangladesh Mangroves: Looking for Indicators for Monitoring Biodiversity

Junaid K. Choudhury^[1]

Abstract

Use of indicators for monitoring the biodiversity health status of mangroves is an innovative approach, not only for Bangladesh mangroves, but also globally. Identification of true indicators for such a purpose needs long-term studies carried out over decades, but the use of experiences and observations is no less valuable in putting up a list of ‘initially identified indicators’ for the purpose. The use of this approach coupled with the field verification of their credibility by experts is tabled in this paper.

Introduction

Bangladesh portion of Sundarbans is the largest productive contiguous mangrove forest in the world, located in the southwestern part of the country between latitudes 89⁰00¢ and 89⁰55¢ East and longitudes 21⁰30¢ and 23⁰30¢ North. This was declared as ‘Reserve Forest’ during 1875-76, and was placed under the Forest Department (FD) for management. Since then its area in Bangladesh has remained unchanged. At the advent of the British rule in India, Sundarbans was twice its current size, most of which is lost to agriculture and habitation. At present it extends over 577,356 hectares of which 175,724 hectares is water.

There are three Protected Areas in Sundarbans Reserved Forests (SRF), which constitute the core area of the World Heritage Site, inscribed in 1997. The total area of the World Heritage Site is about 1,400 km², of which 490 km² is water.

Management of SRF

Management of Sundarbans mangroves under written prescriptions through selection felling was initiated during 1893-94 under a ten-year management plan written by R. L. Heinig. W. F. Lloyd increased the felling cycle to 40 years during 1903-08. Sir Henry Farrington’s management plan, applied during 1906-12 enhanced girth limit for felling. F. Trafford prepared next management plan for the period 1912-32. S. J. Curtis formulated a detailed management plan for Sundarbans suggesting rotations, felling cycles and minimum exploitable girth for major species including "yield calculations". By 1937 it was realized that the existing infrastructure was not capable to adopt such elaborate prescriptions. S. Choudhury revised the plan, which was in force till 1960.

Forestal Forestry carried out a detailed scientific inventory of Sundarbans mangroves and published the report in 1960 which indicated that the average net merchantable volume from trees over 12.7 cm and above, was 53.62 M³ per hectare (Forestal 1960). Based on this inventory A. M. Choudhury prepared the management plan of Sundarbans for the period 1960-80.

The Overseas Development Administration of the United Kingdom conducted second detailed inventory of Sundarbans. The report published in 1985, clearly reflected depletion of the growing stock to the tune of 41.9 and 34 percent of stems per hectare in case of trees with DBH of 7.5 cm and above, for Sundri and Gewa respectively. The regeneration was reported satisfactory (Chowdhury et. al. 1994).

Canonizado and Hussain prepared an integrated forest management plan for Sundarbans in 1998. This management plan supposed to be implemented during 1998 to 2010, suggested a 20-year felling cycle. Annual Allowable Cut (AAC) of 54,000 M³ is prescribed including improvement felling and extraction of Top Dying Sundri (TDS). For Gewa, the AAC prescribed is 53,000 M³.

Since the government of Bangladesh extended the moratorium up to year 2005, this plan could not be implemented. The Khulna News Print Mills (KNM) has stopped Gewa extraction for the time being.

At present only Non Timber Forest Products (NTFPs) are being harvested, that too at a very small scale. Its harvest declined further in 2002, since the government enhanced the stumpage prices, reported to unreasonable.

Present Concerns

The SRF is internationally recognized as an important mangrove ecosystem of high biodiversity value. It is the most important remaining habitat, in the world, of the critically endangered Bengal Tiger (Panthera tigris tigris). A number of other large mammalians once abundant in Sundarbans have already become extinct, including the swamp deer (Cervus duvauceli), one-horned rhinoceros (Rhinoceros unicornis) and wild water buffalo (Bubalus arnee). A recent study by IUCN found that currently 58 species of wildlife, indigenous to the Sundarbans, are threatened, of which 36 are either ‘endangered’ or ‘critically endangered’. Though a comprehensive threat analysis is yet to be carried out, Karim (1994) listed the following:

• Changes in freshwater flow, affecting the vegetation pattern

• Sedimentation increase due to polder construction

• Pollution from agricultural and industrial activities

• Oil spills from boats and ships

• Over-exploitation of wood and NTFPs

• Sea level rise

• Damage due to cyclones and storm surges.

Besides these, the TDS, invasiveness of alien species, loss of biodiversity etc. deserve to receive due attention as concerns towards sustainability of SRF.

There are similar threats to the aquatic ecosystem of Sundarbans. The resultant impact of enhanced shrimp farming along Bangladesh coast has induced a very high demand on natural shrimp fries that exhibit better performance over the hatchery fries. This in turn generated the tremendous pressure on shrimp fry collection from the SRF waters, which has become a major concern now.

A brief preliminary field study undertaken by the author during June 2002 indicates alarmingly low proportion of sapling-size plants in SRF, though the regeneration is adequate. One of the major causes of such situation seems to be the excess and indiscriminate harvest of this size saplings by the shrimp fry collectors, mostly under FD permits, that they use for netting shrimp fries. A rough estimate indicated that these shrimp fry collectors alone chop off over one million such saplings, mostly good and straight looking ones, annually from SRF.

Biodiversity Concept

Biodiversity of natural resources is a new concept. The recent global emphasis on the conservation of germ plasm, coupled with the awareness on sustainability has generated this momentum on biodiversity and biodiversity conservation. IUCN’s red list and the contributions of Species Survival Commission (SSC) assisted in developing a tool to monitor biodiversity. Using the assumption that species status is broadly reflective of the status of biodiversity as a whole, the SSC, while still working on the issue, has so far suggested the following indices (Mainka, S. and McNeely, J. 2001).

• Biodiversity Status Index (BSI)

• Biodiversity Knowledge Index (BKI)

• Biodiversity Trend Index (BTI)

• Cause of Threat Index (CTI)

• Conservation Action Index (CAI)

• Spatial Indices

The intention is to draw attention towards biodiversity trends.

Such momentum under the existing concerns of deforestation and biodiversity loss in SRF led to the launching of Sundarbans Biodiversity Conservation Project (SBCP) since year 2000, by Asian Development Bank (ADB) with financial assistance from the Royal Netherlands Government and the World Bank/the Global Environment Facility (GEF), with the ultimate goal of placing in position a complete sustainable and environment friendly forest management system for SRF to ensure biodiversity conservation as well.

Under such situation, IUCN The World Conservation Union, Bangladesh office has been entrusted with the task of developing a system for monitoring the biodiversity health status of SRF. IUCN Bangladesh has started the implementation of the ADB project since January 2002, which will end in December 2006.

IUCN’s approach in this regard is to build upon a logical step-by-step process of obtaining the information necessary to answer a series of questions in turn, which are

• What ecological zones and characteristic habitats can be identified in the SRF?

• What species are known presently to occur in each zone and/or habitat?

• What species will be used as indicators?

• How will these be measured?

• How the biodiversity health assessment technologies be transferred?

• How will the biodiversity health assessment system be sustainable at the end of the project?

Why Monitor Biodiversity and How

Since the biodiversity loss is a concern in SRF and since the management plan to be adopted is expected to conserve and enhance biodiversity, it is necessary to evaluate its performance. Besides these such monitoring is expected to work as an early warning system for the managers to take measures to combat any probable future disaster.

Concept of Indicators

The conventional tool of assessing biodiversity involve large-scale inventory of the resources, both flora and fauna, which is forbid-ably expensive and almost an impossibility for a poor country like Bangladesh, especially when such activity is required once or twice a year. A reasonably good understanding of the ‘Ecosystem Dynamics’ of the resource and the ecological linkages between the various tires of its biological entities, shall help identify and establish, either some species by itself, or some parameters of a given species, to indicate the biodiversity health status of the given ecosystem or habitat or SRF at large.

That is the basic reason why we are looking for the “Indicators” that can be used for monitoring the biodiversity health status of Sundarbans.

Biodiversity Indicators from the Red List

Red List Program is expected to deliver the vision, goals and objectives as outlined above. Extensive consultations are being held to develop biodiversity indicators or indices from the IUCN Red List. The Red List Program is based on continuous monitoring of a selection of higher taxonomic groups that broadly cover and represent the full range of ecosystems. The Species Survival Commission (SSC) has started the process, which is expected to develop the indices for use by 2003.

Biodiversity Assessment

The biodiversity health assessment model that will be used to assess the biodiversity of SRF is an adaptation of the Pressure-State-Response model promoted by UNDP (Dumanski, J. and Pieri, C. 1994), including “Impact” as a fourth factor. The model identifies the following four main aspects.

• Pressure: Refers to assessing the triggering factors through a threats analysis. In the production zone, it is mainly the use and harvest of resources. In the protection zone, these are hydrodynamic changes and changes in habitat functions.

• State: Refers to assessing the current situation of the resources by means of baseline surveys, mostly through desk study of existing information.

• Response: Refers to the various management actions.

• Impact: Refers to the tangible and quantifiable effects of the response.

IUCN Bangladesh will assess the health status of biodiversity of the SRF at different levels, such as species, ecosystem and habitat.

Biodiversity health assessment will focus on the overall habitat-mix, the macro-ecological setting, the man-made and natural pressures exerted and also the effects of global processes such as climate change and remote processes such as water pollution, sediment load etc.

Conventionally, species have been used in many biodiversity inventories as indicators to measure the health of an ecosystem. Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis will indicate the key elements and for SRF focus will be on

• Species, which are rare, endangered or are of particular interest.

• Species, which are vulnerable.

• Species, which have records of being particularly vulnerable to environmental changes.

• Species, which are important in ecosystem structure and function.

• Biodiversity-rich sites, which are vulnerable or rare or important for species conservation.

IUCN, Bangladesh’s approach to achieve the above rationale is by applying

• Define what is going to be monitored and assessed and identify, jointly with key stakeholders, the pertinent biodiversity assessment indicators.

• Collect and review secondary data and establish the baseline.

• Collect new data, identify and verify indicator species, hotpots and trends.

• Continue to collect data on selected indicators and verify their credibility for SRF.

Seven expatriate and eight national experts, having previous experience on Sundarbans are being engaged to contribute during the project period. They will undertake several visits to Sundarbans, to study various aspects in the following areas.

• Orchids, Lichens.

• Dragonfly, Butterfly.

• Mangrove Regeneration.

• Undergrowth.

• Alien, Invasive Species.

• Crustaceans.

• Cetaceans.

• Herpeto-fauna.

• Birds.

• NTFPs.

• FD Capacity Building

Since the conservation of the invaluable biodiversity of Sundarbans mangroves, has been identified as one of the major goals of management of the resource, it is obligatory to assess the biodiversity health status at given intervals, not only for evaluating the impact of implementation of the given management prescriptions in this regard, but also to alert the managers as an ‘early warning system’.

Till date most of these experts have already undertaken over four field trips. They are working to unveil aspects of ecosystem dynamics of the respective fauna flora sub-groups and verify the ‘Initially Identified Indicators’ regarding their ability to monitor the biodiversity health status of Sundarbans.

There is no doubt that the assignment is not only challenging but also innovative in nature. The task of establishing bio-indicators is a long term one that needs decades of studies. The author as the team leader of the project is hopeful to achieve some success, at least to the tune of firming up some ‘Bio-Alarms’, if not to the full satisfaction of establishing set of ‘Indicators’, for monitoring the Biodiversity health status of SRF.

Initially Identified Indicators

Based on all these stated above, a list of “Initially Identified Indicators” has been developed through various workshops, meetings, brain storming sessions, etc. in conjunction with the stakeholders. Along with professors of various universities, many experienced foresters who have worked in the Sundarbans years after years; relevant stakeholders actively participated during the process of identifying indicators. The list of the “Initially Identified Indicators” emerged as such is as under (IUCN 2002).

Initially Identified Indicators for Monitoring the Biodiversity of SRF
FLORA

Initially Identified Indicators for Monitoring the Biodiversity of SRF
FAUNA

* Scientific names to be obtained later

Conclusions

Identification of true indicators for monitoring the biodiversity of SRF will need studies over periods of decades. But this approach of using the long experiences of available experts who have worked in the Sundarbans for long periods is no less valuable in achieving the goal. Their experience and observations with respect to the ecosystem and ecosystem dynamics of Sundarbans have been fully used in identifying these initial indicators. The field trips by experts that are under way shall give some idea about the credibility of the indicators identified as such. It is expected that indicators, once firmed up will work as early warning system or “Bio-Alarms” for the managers to signal probable change in future to take necessary steps towards conservation and sustainability.

This is an innovative and absolutely new approach not only for Bangladesh mangroves but also for the mangroves at large. This work may be taken further and continued over long periods of decades to firm up and establish a set of true indicators for monitoring the biodiversity health status of SRF, which may be redressed for global use.

Reference

Chowdhury, R. A. and Ahmed, I. 1994 History of Forest Management. Mangroves of the Sunderbans Volume two: Bangladesh. Zakir Hussain and Gayatri Acharya (eds.). IUCN Publication. P 155-180

Dumanski, J. and Pieri, C. 1994 Application of the Pressure-State-Response Framework for the Land Quality Indicators Program.

Forestal Forestry and Engineering International Ltd. 1960 Inventory of Sundarbans Forests. Vancouver, Canada.

IUCN. Bangladesh 2002 Workshop Reports on Initial Identification of Indicators. Conservation Monitoring of Sundarbans Biodiversity.

Karim, A. 1994 Environmental Impacts. Mangroves of the Sunderbans Volume two: Bangladesh. Zakir Hussain and Gayatri Acharya (eds.). IUCN Publication. P 203-217

Mainka, S and McNeely, J. 2001. The IUCN Red List of Threatened Species__ A Tool for Monitoring Biological Diversity.

NB: The author gratefully acknowledges the use of information of the on going project of IUCN, Bangladesh under ADB.

Contact Information

Name: Junaid K. Choudhury. CF (Rtd)

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Team Leader. SBCP-IUCN
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