Biodiversity and Ethnobiology

IUCN Cascade Development Project Information Brief No. 2

of the Kapiriggama Small Tank Cascade System

Background

The cascade landscape consists of a mosaic of agro-ecosystems and natural systems. It is rich in natural resources, harbouring many economically and ecologically high-value species and habitats. The local community depends on these resources for the tangible and intangible needs of their daily lives. Continual overexploitation of cascade ecosystem components has resulted in the accelerated decline in the abundance of a wide range of species and habitats. Better understanding of human interactions with biodiversity is fundamental to the management and decision-making process in the rehabilitation of cascade landscapes.

A study was carried out to assess species diversity and ethno-biology (the interdisciplinary study of how human cultures interact with and use their native plants and animals), with the following objectives:

• To document ecological features of the cascade ecosystem and the species therein, as a part of understanding species requirements and ecological services provided; also to evaluate habitat degradation and recommend remedial actions.

• To document species of ethno-biological value that improves the understanding of the interaction between humans and biodiversity in a cascade ecosystem. This will open avenues for more socially relevant on-site and off-site ecosystem restoration actions.

• To make recommendations to enhance ecological sustainability of the cascade; while developing the well-being of local communities.

Methodology

A total number of 23 tanks were sampled during the research period (from 2014 to 2015). Vegetation was sampled using a 5m x 50m belt sampling technique. Plant species were identified, classified and specimens deposited in the National Herbarium, for future reference and authentication. All groups of vertebrates (freshwater fish, amphibians, reptiles, birds and mammals) and selected invertebrate groups (freshwater crabs, dragonflies and butterflies) encountered at the site were identified and documented.

Ethno-biological data was collected informally through opportunistic, semi-structured interviews with local communities within the cascade. A number of villagers (ranging from 40-82 years old) were interviewed to gather relevant ethno-botanical and ethno-zoological information.

Results

The tank cascade is a mosaic of different types of vegetation influenced by water regimes, type of soil, other biotic interactions and human activities. These include natural and managed habitat types, each with characteristic species.

Tank and its proximate habitats• Gasgommana (which functions as a catchment

forest), with 201 recorded plant and 187 animal species. This low gradient, relatively flat land bordering the tank is flooded annually during the north-east monsoon period. The plants — such as Terminalia arjuna (Sinhala: Kumbuk; Tamil: Marudu) — are considerably influenced by the water overflowing from the tank. This habitat is home to.

• Kattakaduwa (a strip of swamp forest), with 153 plant and 193 animal species. This forest is a natural biofilter that traps pollutants in the water, before it irrigates the low-lying paddy tracts. The thick root system of trees and shrubs act as a protective cushion for the sloping land. This strip is luxuriant because of the readily available water, and resembles a patch of rainforest. Plants include Terminalia arjuna.

• Littoral vegetation (peripheral, shallow tank bed area),

with 68 plant species. For several months of the year, this zone between water and land is flooded and is muddy and unstable. Plants such as — Cassia tora (Sinhala: Thora; Tamil: Vaddutakarai) and reeds — are, therefore, adapted to this seasonal flooding.

• Tank bund vegetation, with 153 plant species. The sloping sides of the tank bund primarily hold dense vegetation comprising low growing plants — such as Acalypha indica (Sinhala: Kuppameniya; Tamil: Kuppameni). These provide an excellent cover against erosion caused by run off and strong winds.

• Open water zone, with 40 plant and 141 animal species. Vegetation is dominated by Lotus (Nelumbo nucifera; Sinhala: Nelum; Tamil: Thamarai). Depending on the duration for which the depth of water is maintained, the vegetation is characterised by emergent, rooted, floating or submerged water plants.

Cultivation • Chena (shifting cultivation), with 55 plant species.

These areas are dominated by shrubby and herbaceous crop species, such as Abelmoschus esculentus (Sinhala: Bandakka; Tamil: Vendikkai). During the rainy season, there is abundant vegetative cover. Once harvesting is over, the land is left fallow.

• Home gardens, with 42 plant species, such as Artocarpus heterophyllus (Sinhala: Kos; Tamil: Palapalam). Well-developed home gardens have a structure that mimics a near-natural forest. These habitats are home to 154 species of animals.

• Paddy lands — with 17 plant species — have a simple structure, consisting exclusively of a herbaceous layer up to 75 cm. The composition of plants in these fields changes rapidly with the paddy cycle, and is governed by the flooding and subsequent drying off of the fields when the crop matures. There are 191 species of animals found in this habitat.

Natural/semi natural vegetation • Near natural forests, resembling tropical deciduous

forests, are found in some of the higher grounds of the cascade and comprise four recognisable strata; a continuous tree canopy, some 20m-30m high; a sub-canopy up to 15 m; shrubs up to 5 m and herbaceous plants below 1 m. Common canopy plants include Chloroxylon swietenia (Sinhala: Burutha; Tamil: Muthirai) and Drypetes sepiaria (Sinhala: Weera; Tamil: Weerai).

• Scrublands are thick, impenetrable thorny or spiny and woody vegetation growing up to 2 m-4 m in height. Thirty two species have been recorded in this habitat, including Dichrostachys cinerea (Sinhala: Katu andara; Tamil: Vindattai).

Plant diversityThere are 347 species of plants belonging to 84 families in the Kapiriggama cascade. Among them there are nine endemic species, including Vernonia zeylanica (Sinhala: Pupula; Tamil: Kappilay); three endangered (EN) species, including Salacia reticulata (Sinhala: Kotala himbutu) and 22 vulnerable (VU) species, including Nymphaea nouchali (Sinhala: Nil manel; Tamil: Neelambal).

Animal diversity

Overall, a total of 285 animal species were recorded from the Kapiriggama cascade, including seven land snail species, 20 dragonfly species, 46 butterfly species, one freshwater crab species, 25 freshwater fish species, 13 amphibian species, 26 reptile species, 118 bird species, and 29 mammalian species.

Among these, there are 24 endemic species, including Sri Lanka Grey Hornbill (Ocyceros gingalensis) (See picture below.) There are also 14 migratory bird species, including the Whiskered Tern (Chlidonias hybrid); four exotic species and four domestic mammals.

The highest number of animal species were recorded from Konakumbuk wewa (214 spp), followed by Kapiriggama tank (208 spp), and then Messellava tank (205 spp); the lowest number of species was recorded from Wanikulama tank (68 spp). (See Brief # 1 for locations.) The highest numbers were recorded from the

middle-sized tanks, which contain water throughout the year. The lowest numbers were recorded from seasonal small tanks, which are only sustained during the monsoon period.

With respect to habitats, the highest numbers of animal species (193) were recorded from forest, shrub and marshy habitats in the kattakaduva forest, followed by the gasgommana (187), paddy lands (181), home gardens (154), and tanks (141).

A total of eight nationally Threatened animal species representing three Endangered and five Vulnerable species were recorded from the cascade system (including the Tic tac-toe barb — Pethia melanomaculata). Another 12 nationally Near Threatened (NT) species; and one nationally Data Deficient (DD) dragonfly species were also recorded from the study site.

A number of insectivorous bird species which were found in the kattakaduva feed on pest insects on paddy and adjacent farm lands, thus functioning as a natural form of pest control. Day hunters include the Ashy, Plain, and Grey-breasted Prinias (Prinia socialis, Prinia inornata and Prinia hodgsonii respectively) and the Common Myna (Acridotheres tristis).

Also within the cascade are night hunters, such as Night jars (Caprimulgus asiaticus) which feed on night-dwelling insects, and civets (Viverricula indica, Paradoxurus hermaphoditus), small cats and jackals (Canis aureus), which hunt rodents and crabs that are also crop pests.

Three potential Invasive Alien Species — the Giant African snail (Lissachatina fulica), Tilapia (Oreochromis niloticus) and the Snakeskin Gourami (Trichogaster pectoralis) were also recorded from the cascade system.

Diversity of species used by communities

A total of 231 plant types (species and varieties) and 54 animal species were reported to be used for various purposes such as food, medicine, timber, tools, fuelwood, fibre, livestock feed and rituals. For plants, more than half of these were used as food and medicine.

Amongst animals, a total of 61 species were used by these communities as food, medicines, animal products, ornament, as pets, and for ritual practices. As with plants, the most common use was as food, with 72% being eaten for their flesh.

The Kapiriggama cascade community, is dependent on paddy, chena and home garden cultivation, which is, in turn, dependent on monsoonal rains. Therefore, they have developed their own weather forecasting practices based on the surrounding environment. For example, the flight patterns of, among others, the Asian Palm Swift (Cypsiurus balasiensis); calls of the Common coucal (Centropus sinensis) and the nesting behaviour of the Red-wattled lapwing (Vanellus indicus) are used for predicting the weather. Other indicators used include call of frogs during the dry season (indicates rain in a few days) and fire ants (sudden appearance of these ants walking in a line on the ground, predicts rain).

December 2015

For more information contact

Shamen Vidanage, Programme Coordinator,IUCN Sri Lanka Country Office53, Horton Place, Colombo 7, Sri Lankatel: +94-112682418, fax: +94-112682470email: shamen.vidanage@iucn.orghttps://www.iucn.org

Access technical note from here.

Issues threatening the biodiversity of the Kappirigama Tank Cascade area

Agricultural expansion into non-target areas: There is considerable pressure on the land for agricultural expansion. Deforestation and the illegal logging of trees along stream banks are reported in the area. The uncontrolled clearance of forests for chena/paddy cultivation practices is also resulting in the deterioration of gasgommana vegetation and, ultimately, the water resources of the area. This also leads to soil erosion and silt accumulation in the tanks. Grazing pressure from livestock can also result in the degradation and destruction of natural vegetation.

Spread of Invasive Alien Species (IAS)A total of 10 invasive alien plants and three IAS animals were recorded from the cascade area. Invasive alien species spread rapidly, replacing native species, and are very difficult to eradicate once established.

Unsustainable biomass extractions and loss of vegetative coverHunting is a common practice within the Kapiriggama cascade and a commonly hunted species, the Barking Deer (Muntiacus muntjak) is a Near Threatened species. There is also unsustainable extraction of fuelwood and illegal felling of valuable timber species.

Pollution and siltation of water bodies In addition, the heavy application of agrochemicals can result in the pollution of water and soil. As a practice, local communities do not engage in sustainable agriculture.

Lack of awareness among communities There is a general lack of awareness about the cascade ecosystem; the benefits and services obtained from this site and its biodiversity. Mobilisation of local communities for conservation action is also poor.

Some of the proposed remedial actions for environmental sustainability

• Cascade ecology is just one important piece in the complex restoration jigsaw where social, cultural and economic aspects have contributed to shaping the landscape. The starting point of key issues of environmental sustainability is human behaviour — particularly the consumption of natural resources.

• Creating awareness regarding the ecological, hydrological and cultural values of the site, threats to the site and how they contribute to degradation, through conservation education among school children, local communities and key stakeholders;

• Engaging in ecological restoration of degraded lands, for example, restoring the gasgommana and kattakaduva by planting suitable trees, as well as enhancing riverine vegetation. (See also Brief # 3.)

• Introducing alternative livelihoods with non-agriculture based income-generating activities to reduce pressure on resources;

• Promoting eco-agricultural and sustainable agriculture practices and traditional systems to

reduce dependency on agrochemicals; promoting soil conservation measures;

• Creating awareness regarding IAS among school children, local communities and key stakeholders; establishing a network of community organisations and mobilising them for mechanical control of IAS.

• Introducing agro-forestry for multiple needs, including promotion of useful agro-forestry plants in home gardens; establishing multi-layer live fencing for fuelwood and enriching home gardens by introducing valuable timber species, for example, in order to reduce dependency on forest resources.

• Creating awareness in both the community and the local authorities relating to overexploitation of natural resources: increasing the presence of regulatory authorities — for example, the Department of Wildlife Conservation and the Forest Department — and ensuring law enforcement; introducing livestock practices, such as the rearing of back-yard poultry, for subsistence use. All of the above will reduce overexploitation of resources.

• Increasing research on cascade ecosystems by involving universities; also involving schoolchildren in basic documentation of biodiversity within the system.

• Establishing a funding mechanism for the above. • Moblising all stakeholders in a cascade watershed

management programme.

Photographs: Cover: Egrets and cormorants in Galkadawala Tank, Naalin Perera © IUCN; page 2: Blue mist (Memecylon umbellatum), a plant found in the area, Sampath de Alwis Goonatilake © IUCN; page 3 left: Grey hornbill, © Sriyanie Miththapala; right: Tic-tac-toe barb, Sampath de Alwis Goonatilake © IUCN; page 4: Lotus pickers, Sampath de Alwis Goonatilake © IUCN.