S.C. Rai and Adon Raleng *Department of Geography Delhi School of Economics University of Delhi, Delhi India*

#### **1. Introduction**

232 Ecosystems Biodiversity

Ngailo, J.A., Kaswamila, A.L. and Senkoro, C.J. (2002). Rice farming system of the

Rweyemamu R. 2009. The Role of Bahi Swamp Wetlands in Enhancing Household Food

Tetsuya S. and Kuniyasu M (2005). Organic matter dynamics control plant species coexistence in a tropical peat swamp forest. Proc Biol. Sci. 272(1571):1503–1510 Tomáš H & František K. (2008). Mechanisms of species coexistence in semi naturalmeadow

March, 2002. 23pp.

University of Agriculture Tanzania 74 pp

communities; importance of species traits

Wasukuma and its Contribution to Poverty Alleviation. *Presented at the Fifth REPOA Workshops* held at the White Sands Hotel, Dar es Salaam, Tanzania, 21-22,

Security and Income of Adjacent Communities. Unpublished MSc Thesis Sokoine

Wetlands are complex ecosystems often occupying the interface between land and water. Wetlands function as part of the landscape with or without the presence of humans. They have value because many of their functions have proved to be useful to humans but are at the same time ecologically sensitive and adaptive systems. The increasing demand and pressures on wetlands without understanding their nature and dynamics have often led to their degradation, thereby threatening livelihood of the communities' dependent upon these resources. The world's freshwater lakes of today are vanishing at a much faster rate than they used to be a century ago. In some cases, even the area is lost (Raleng, 2010). Current emphasis on wetland management has two objectives: firstly to conserve biotic diversity and secondly to maximize economic gains. This explains why in recent years much attention has been directed towards the formulation and operation of sustainable management strategies for wetlands1. Wetlands comprise lakes, rivers, marshes, bogs and similar areas and they are generally regarded as areas of land that remain waterlogged for a substantial period of the year. Wetlands fulfill a wide range of essential functions include flood proofing, natural sewage treatment, shoreline anchoring and dissipation of erosive forces, sediment trapping, nutrient retention and removal and recharging of aquifers. In addition, many food chains depend upon wetland productivity and form important habitats for fisheries and wildlife. Wetlands are important for maintaining

<sup>1</sup> Wetlands are the only single group of ecosystems to have their own international convention. The call for wetland protection gained momentum in the 1960s, primarily because of their importance as habitat for migratory species. A series of conferences and technical meetings culminated in the "Convention on Wetlands of International Importance Especially as Waterfowl Habitat" (better known as the Ramsar Convention) which came into force in 1975. In 1985 there were 38 signatories, in 1991 this increased to 60, and by 1993 the total number was 75 countries (Dugan, 1993). Currently 153 nations have joined the Ramsar Convention as Contracting Parties and more than1600 wetland sites around the world covering 145 million hectares; have been designated for inclusion in the Ramsar List of wetlands of International Importance (Ramsar Convention Secretariat, 2006). India has designated 25 wetland sites as Ramsar Sites of International Importance.

Ecological Studies of Wetland Ecosystem in Manipur Valley from Management Perspectives 235

resources for their sustenance. Its biological richness, and uniqueness of habitat, has resulted in its designation as a "Wetland of International Importance" under the Ramsar Convention, a distinction it shares with just five other lakes in India. The lake is famous for its floating mats of vegetation locally called *phumdi*, which are heterogeneous mass of soil, vegetation and organic matter at various stages of decomposition and for being the only refuge of the endangered S*angai* (Manipur brow-antlered deer) which is closer to extinction (LDA &

The origin and evolution of Loktak Lake may be ascribed to tectonic activity and neotectonism remarkably influenced by a long history of fluviolacustral processes. The Loktak Lake is situated about 38 km south of Imphal, the capital city of Manipur. It lies between longitudes 93 46′ to 95 55′ E and latitudes 24 25′ to 24 42′ N (Fig. 1). Overall 53 settlements in and around Lokatak Lake is located having 279935 persons, which accounted for 12% of the total population of Manipur state. The lake, along with its surrounding swamps (locally called *pats*) is an integral part of the floodplain of Imphal River. The oval-shaped Manipur valley (height: 746-798 m asl), bounded by mountains rising 2000-3000 m asl along with the Imphal River and its tributaries (Iril, Thoubal, Heirok, Khunga and Chakpi), and other streams (Nambul, Nambol and Ningthoukhong) that pour their silt-laden waters directly into Loktak Lake. Morphometric data are

Maximum length (L) 26 km Maximum breadth (B) 13 km Shore line length (L) 126 km Orientation N – S Surface area 287 km² Area covered by *Phumdis* 107 km² Area covered by islands 17.2 km² Area covered by encroached land of fish farm, paddy field etc. 89.3 km² Area of open water 73.5 km² Mean breadth 11.04 km Shoreline development 2.10

Total volume of water 550.21M m³ Maximum depth (Zm) 4.58 m Mean depth (V:A) 1.92 m Mean depth : Maximum depth (Z:Zm) 0.42 Development of volume 1.26 Area of catchment's 980 km² Surface area : Catchment's area 0.293 Index of lake permanence 1.92

WISA, 1998).

summarized in Table 1.

Table 1. Morphometry of Loktak Lake

biodiversity and securing livelihood for local communities. The wetlands are most productive life support system in the world.

Wetland ecosystems are among the most threatened of all environmental resources. These bodies are getting more and more polluted due to anthropogenic activity leading to changes in land-use/cover characteristics and subsequently hydrologic processes, specifically through the large-scale conversion of forests to other land-uses (Jain et al., 2000; Mao & Cherkauer, 2009). After large areas of natural wetlands in all parts of the world were totally lost by drainage and landfills or were highly degraded by other human activities, the values and functions of natural wetlands are now being rediscovered (Gopal, 1991). At present, most of the wetlands of India and elsewhere are threatened to extinction mainly because of cultural eutrophication and conversion into agricultural land. Substantial changes in land-use/cover have occurred over north-eastern part of India in the past few decades with the shortening of j*hum cycle*, spread of settlement and increasing use of land resources for agriculture and economic development. Shifting cultivation, also known as "Slash and Burn" or "Swidden agriculture" and as "Jhum cultivation" in north-east India, where it is a predominant activity for the majority of the population, is often described as an inefficient, destructive practice, which contributes to deforestation and lowland sedimentation (Sillitoe, 1998). Reducing the *jhum cycle* during recent years has put pressure on resources and thus the productivity of land degradation, increased levels of soil erosion, hydrological imbalances and forest degradation all of which have caused reductions in yields and insecurity of food sources (Toky & Ramakrishnan, 1981). Understanding the characteristics of hydrological processes and regime change is important for driving the solutions to rational use of the lake water and limiting the environmental degradation in the region.

In India, studies on wetlands have not yet gained importance though few beautiful fresh water lakes of the Himalaya viz., Dal Lake of Kashmir, Khecheopalari Lake of Sikkim and Nainital Lake of Uttarakhand are losing their charms and reducing their areas at alarming rate. The data on lakes are not scientifically compiled, so it is difficult to provide solutions to lake problems. Several earlier studies have focused on ecological, wetland ecosystem management, rather than on the catchment's scale hydrologic impacts of land-use/cover change. Singh (1989) studies wetland ecosystem management perspective of fish, wildlife and environment in Loktak Lake. Singh & Shymananda (1990) studied management of Loktak Lake. Wetland ecosystems are among the most threatened of all environmental resources. It is important to understand the ecosystem processes in a wetland and the factors responsible for maintaining characteristics which impart particular value to it. There is a broad understanding of land-use change but their associations with the hydro-ecological consequences are not understood properly. So, there is a need to understand the relationship of these changes and those problems. Therefore, in view of this, the present study is focused on ecological studies of wetland ecosystem in Manipur valley from management perspectives, which need immediate conservation.

#### **2. The Loktak Lake ecosystem**

Loktak Lake, the largest natural lake in north-eastern India, occupies the southern part of Manipur valley, which runs north-south through the centre of Manipur state. Due to its importance in the socio-economic and cultural life of the people, it is considered as "The lifeline of Manipur". A large population living in and around it depends upon the lake

biodiversity and securing livelihood for local communities. The wetlands are most

Wetland ecosystems are among the most threatened of all environmental resources. These bodies are getting more and more polluted due to anthropogenic activity leading to changes in land-use/cover characteristics and subsequently hydrologic processes, specifically through the large-scale conversion of forests to other land-uses (Jain et al., 2000; Mao & Cherkauer, 2009). After large areas of natural wetlands in all parts of the world were totally lost by drainage and landfills or were highly degraded by other human activities, the values and functions of natural wetlands are now being rediscovered (Gopal, 1991). At present, most of the wetlands of India and elsewhere are threatened to extinction mainly because of cultural eutrophication and conversion into agricultural land. Substantial changes in land-use/cover have occurred over north-eastern part of India in the past few decades with the shortening of j*hum cycle*, spread of settlement and increasing use of land resources for agriculture and economic development. Shifting cultivation, also known as "Slash and Burn" or "Swidden agriculture" and as "Jhum cultivation" in north-east India, where it is a predominant activity for the majority of the population, is often described as an inefficient, destructive practice, which contributes to deforestation and lowland sedimentation (Sillitoe, 1998). Reducing the *jhum cycle* during recent years has put pressure on resources and thus the productivity of land degradation, increased levels of soil erosion, hydrological imbalances and forest degradation all of which have caused reductions in yields and insecurity of food sources (Toky & Ramakrishnan, 1981). Understanding the characteristics of hydrological processes and regime change is important for driving the solutions to rational use of the lake water and

In India, studies on wetlands have not yet gained importance though few beautiful fresh water lakes of the Himalaya viz., Dal Lake of Kashmir, Khecheopalari Lake of Sikkim and Nainital Lake of Uttarakhand are losing their charms and reducing their areas at alarming rate. The data on lakes are not scientifically compiled, so it is difficult to provide solutions to lake problems. Several earlier studies have focused on ecological, wetland ecosystem management, rather than on the catchment's scale hydrologic impacts of land-use/cover change. Singh (1989) studies wetland ecosystem management perspective of fish, wildlife and environment in Loktak Lake. Singh & Shymananda (1990) studied management of Loktak Lake. Wetland ecosystems are among the most threatened of all environmental resources. It is important to understand the ecosystem processes in a wetland and the factors responsible for maintaining characteristics which impart particular value to it. There is a broad understanding of land-use change but their associations with the hydro-ecological consequences are not understood properly. So, there is a need to understand the relationship of these changes and those problems. Therefore, in view of this, the present study is focused on ecological studies of wetland ecosystem in Manipur valley from

Loktak Lake, the largest natural lake in north-eastern India, occupies the southern part of Manipur valley, which runs north-south through the centre of Manipur state. Due to its importance in the socio-economic and cultural life of the people, it is considered as "The lifeline of Manipur". A large population living in and around it depends upon the lake

productive life support system in the world.

limiting the environmental degradation in the region.

management perspectives, which need immediate conservation.

**2. The Loktak Lake ecosystem** 

resources for their sustenance. Its biological richness, and uniqueness of habitat, has resulted in its designation as a "Wetland of International Importance" under the Ramsar Convention, a distinction it shares with just five other lakes in India. The lake is famous for its floating mats of vegetation locally called *phumdi*, which are heterogeneous mass of soil, vegetation and organic matter at various stages of decomposition and for being the only refuge of the endangered S*angai* (Manipur brow-antlered deer) which is closer to extinction (LDA & WISA, 1998).

The origin and evolution of Loktak Lake may be ascribed to tectonic activity and neotectonism remarkably influenced by a long history of fluviolacustral processes. The Loktak Lake is situated about 38 km south of Imphal, the capital city of Manipur. It lies between longitudes 93 46′ to 95 55′ E and latitudes 24 25′ to 24 42′ N (Fig. 1). Overall 53 settlements in and around Lokatak Lake is located having 279935 persons, which accounted for 12% of the total population of Manipur state. The lake, along with its surrounding swamps (locally called *pats*) is an integral part of the floodplain of Imphal River. The oval-shaped Manipur valley (height: 746-798 m asl), bounded by mountains rising 2000-3000 m asl along with the Imphal River and its tributaries (Iril, Thoubal, Heirok, Khunga and Chakpi), and other streams (Nambul, Nambol and Ningthoukhong) that pour their silt-laden waters directly into Loktak Lake. Morphometric data are summarized in Table 1.


Table 1. Morphometry of Loktak Lake

Ecological Studies of Wetland Ecosystem in Manipur Valley from Management Perspectives 237

About two-thirds of Manipuri's population lives in the valley (one of the most densely populated areas in India with 415 persons per km2). These communities are directly or indirectly dependent upon the lake itself. The productivity of the surrounding agricultural fields is on account of the nutrient rich waters of the lake. The wetland's enormous fish resources support large fishing communities in and around the lake area, in particularly villages of Moirang, Ithing, Karang, and Thanga, who completely rely for their livelihood on fish catches. About 60% of the fish catch of Manipur comes from Loktak Lake alone. Besides these vital functions, the lake is also being used for a major lift irrigation and power project. There are 14 hills appearing as islands in the southern part of the lake. Only four of them, viz., (i) Thanga island, (ii) Karang island, (iii) Ithing island, and (iv) Sendra island are inhabitat. These islands are connected to the lake shore through motorable roads and bridges except Karang island, which is isolated from the other three and can be reached only by boat. The lake can be broadly divided into northern, central and southern zones. The three zones are characteristically different in terms of biodiversity and pressure of human activities. Therefore, these three zones i.e. Northern, Central and Southern were considered for the sampling site. Six sampling sites, two each in every zone, all in the lake periphery except one site (Site IG, which is an island). The three disturbed sites were selected in the study are Moirang (Site MO); Khathinungei (Site KI) and Mayang Imphal (Site MI) whereas the comparatively undisturbed

Land is used to meet a multiplicity and variety of human needs and to serve numerous and diverse purposes. When the users of land decide to employ its resources towards different purposes, land-use change occurs producing both desirable and undesirable impacts. Landuse is the utilization of all developed and vacant lands on a specific space at a given time. The increasing pressure due to population and human activities of land resources to meet the increasing demands are contributing to significant transformation of land for a variety of

Shifting cultivation is the characteristic feature of agriculture in the hilly catchments of the Loktak Lake. This form of land-use practices occupies a distinct position in the tribal economy, with about 74% of the tribal population deriving its sustenance from this traditional mode of agriculture. But due to rapid increase in population, the shifting cycle which until a few decades was more than 20 years has reduced to less than five years. This reduction has led to land degradation and increased soil erosion leading to sedimentation of water bodies consequently reducing its water holding and overall carrying capacity. The analysis of land-use/cover change is essential to formulate the suitable plan for lake

The data for land-use\cover of Loktak Lake catchment have been derived from secondary sources. The temporal land-use/cover data of Loktak Lake catchment of 1990 and 2004 including structural component data of 2004 have been obtained from Loktak Development Authority and Manipur Remote Sensing Application Centre, Imphal. The land-use/cover map has been prepared by using high resolution data like IKONOS satellite, for some area and merge data of 2.5m resolution using LISS-III (Linear Imaging Self Scanner) and PAN (Panchromatic) data. By comparing the temporal land-use data of 1990 and 2004, major land-use/cover changes that occur between the two periods were obtained. Intensive field

sites are Hayel (Site HA), Khordak (Site KH) and Ithing (Site IG).

investigations were carried out for ground verification.

**3. Land-use/cover change** 

land-uses.

conservation.

Fig. 1. Location of Loktak Lake

About two-thirds of Manipuri's population lives in the valley (one of the most densely populated areas in India with 415 persons per km2). These communities are directly or indirectly dependent upon the lake itself. The productivity of the surrounding agricultural fields is on account of the nutrient rich waters of the lake. The wetland's enormous fish resources support large fishing communities in and around the lake area, in particularly villages of Moirang, Ithing, Karang, and Thanga, who completely rely for their livelihood on fish catches. About 60% of the fish catch of Manipur comes from Loktak Lake alone. Besides these vital functions, the lake is also being used for a major lift irrigation and power project. There are 14 hills appearing as islands in the southern part of the lake. Only four of them, viz., (i) Thanga island, (ii) Karang island, (iii) Ithing island, and (iv) Sendra island are inhabitat. These islands are connected to the lake shore through motorable roads and bridges except Karang island, which is isolated from the other three and can be reached only by boat. The lake can be broadly divided into northern, central and southern zones. The three zones are characteristically different in terms of biodiversity and pressure of human activities. Therefore, these three zones i.e. Northern, Central and Southern were considered for the sampling site. Six sampling sites, two each in every zone, all in the lake periphery except one site (Site IG, which is an island). The three disturbed sites were selected in the study are Moirang (Site MO); Khathinungei (Site KI) and Mayang Imphal (Site MI) whereas the comparatively undisturbed sites are Hayel (Site HA), Khordak (Site KH) and Ithing (Site IG).
