Ecosystem services are the multitude of benefits that nature provides to society. The primary service of VTCSs have been the storage and management of rainwater to enable year-round paddy cultivation, however they also provide multiple other ecosystem services that fall into four main categories:
- Provisioning Services: these are the material benefits people get from ecosystems for e.g., food
- Regulating Services: these are the benefits obtained from the regulation of ecosystem processes e.g., crop pollination
- Cultural Services: these are non-material benefits people gain from ecosystems, for e.g., cultural heritage values
- Supporting services: these are necessary to produce all other ecosystem services, for e.g., providing a habitat for wild animals and insects.
Explore the figure below to find out more about the ecosystem services provided by VTCSs.
Nutrient Recycling
VTCSs are a conducive environment for ‘nutrient cycling’- the process where plants and animals use nutrients while they are alive and then pass them along to new plants and animals when they die.
Habitat for wildlife
With their varied landscape, VTCSs have historically been home to a diverse range of wildlife including elephants, panthers and crocodiles. In the past few decades, with the expansion of human settlements and irrigated agriculture into wildlife habitat, there has been a rise in human-wildlife conflicts with multiple negative impacts.
Nature-based tourism
Nature-based tourism involves responsible travel to natural areas such as national parks and wilderness areas, where tourists can enjoy the rich biodiversity of the areas they visit, while doing little to no harm to it and possibly improving the livelihoods of the local community. Examples of activities one can enjoy in cascade landscapes include birdwatching, stargazing and boat rides; as well as more ‘adventure tourism’ activities such as rock climbing and hiking.
Flood and drought mitigation
When well maintained and managed, VTCSs help moderate the effects of extreme weather events (e.g., floods and droughts) by capturing runoff and storing storm water in their numerous tanks. As climate change is expected to worsen the frequency, intensity, and impacts of such extreme weather events, a better understanding of how VTCSs are designed and work could help improve climate change adaptation efforts, globally.
Microclimate regulation
VTCS components such as the gasgommana (an area planted with large trees of the same species that acts as a wind break) and kattakaduwa (forest strip between tank boundaries and paddy fields) act as upstream and downstream wind barriers, respectively. They help mimimise evaporation from the surface of tanks but also help create a pleasant and cool microclimate around the VTCSs making it an area where the local community can relax and socialize.
Silt trap
Different components of VTCSs trap silt which is then used as a fertilizer for crops, however in recent year these components have been neglected causing a reduction in tank capacity due to a build up of silt.
Water desalination
Trees in the kattakaduwa (forest strip below tank boundaries) absorb salts from water that seeps out of tank bunds. If not for this "desalination" the water escaping from tank bunds can damage paddy. Kiwul ela , which is the common drain of the irrigated ares, also helps remove saline water from paddy fields, thereby preventing an excessive increase of water-soluble salts in the soil.
Roofing, thatching & basket weaving
Traditionally, local women weave mats, bags, hats etc. from raw materials, especially reeds, collected from their surrounding landscape. Reeds used are Gallaha, Havan, Vetakeiya, Borupang, Thunhiriya which grow in wetlands found around the tanks and the paddy fields- of these, Gallaha is the most expensive. Leaves of Palmyra trees and Vetakeiya are also used.
Water for irrigation
The VTCS is considered one of the oldest and most advanced agricultural irrigation systems that has evolved in the world. More than 14,000 small village tanks are still in use in the dry and intermediate zones of Sri Lanka, with an irrigation potential of paddy fields that have a total area of about 245 soccer fields!
Habitat for pollinators
With a variety of flowering plants that can provide food and nesting spaces, cascade landscapes are an ideal habitat for pollinators such as bees, butterflies and moths. Tree species such as mousey mi (Madhuca longifolia) and mango also attract bats-a commonly forgotten, but important pollinator.
Educational and recreational site
Indigenous knowledge (IK) provides the basis for techniques and practices that guide many aspects of rural life such as agriculture, health care, food preparation, education, natural resource management, social activities etc. IK has been passed down through multiple generations of cascade landscape communities through instruction, apprenticeship and observation; as well as through folk art.
Traditional dancing, folklore, folksong, folk poems, folk music, rituals, traditional festivals, and folk drama, have evolved in the village tank farming culture during its long existence and not only celebrate cultural heritage but are also an opportunity for local communities to gather, socialize and be entertained.
Traditional medicines and biopesticides
Butterfly pea and hibiscus flowers are abundant in tank villages and are used to make Nil katarodu & Pokuru wada - antioxidant-rich drinks that are believed to have multiple health benefits.
On the other hand, Kukurumanna (Benkara malabarica) fruits used to control attacks by rats and insects during paddy storage.
Nesting and feeding ground for a variety of birds
VTCSs are home to birds such as the crested serpent eagle, stork-billed kingfisher and baya weaver. Traditionally, the behavior patterns of many of the birds found here have been used to predict weather!
E.g., if the baya weavers build their nests near the water level (tank or canal) a drought or less rain in the next monsoon season can be expected.
Alternatively, if their nest is built on top of the trees, heavy rains can be expected.
Fish for food
Traditionally, fishing in the tanks was done during the dry season. As part of their fishing custom, community members caught the fish, shared it amongst all the village houses and then dried any surplus fish so that it could be stored for use in the rainy season.
Fish has been an important source of protein in the diets of cascade landscape communities and examples of commonly caught fish from the tanks include the striped snakehead (Channa striata) and tank goby fish (Gleogogobius giuris).
Firewood and timber
Feeding livestock
There are several community-adapted livestock breeds such as: Batu Haraka, mixed varieties of cattle and goats that graze around the tanks. Although the milk yield of the Batu Haraka cattle breed is low, locals find it a low input breed requiring minimal care with regard to health needs, feeding and dry conditions.
One can observe that in the dry season animals feed on dry grass which is usually rejected by high-yielding, introduced breeds.
Indicator species and biological pest control
VTCSs are home to dragonflies, which are not only indicators of clean and fresh water, but also help control the mosquito population, thereby reducing the risk of spreading malaria and dengue fever.
Water for bathing and washing
Water for bathing and washing
Water for drinking
Stored water in the tanks recharge groundwater thereby facilitating domestic water use through wells.
Food for a diverse and healthy diet
A three-fold farming system has evolved in the cascade landscape comprising a threefold system of land-use; centering on irrigated rice (paddy) cultivation in the tank area, chena, a form of shifting cultivation of other diverse crops in the communal uplands under rain-fed conditions, and perennial crops, mostly trees, in home gardens which make use of sub-surface moisture.
Edible wild or semi-wild plants can also be gathered directly from paddy fields, tank bunds or surrounding forests.
As a result, generations of cascade landscape communities have been able to prepare diverse, nutritious and delicious meals using locally-grown produce.
Home gardens
These are small areas of land, around or near a family residence, where a variety of foods are grown. Harvests from these gardens- which can include vegetables, fruits, plantation crops, herbs, spices, and medicinal plants- are usually supplementary, rather than a main source of family consumption and income.
Coconut, mango and papaya, are some of the most commonly grown species in the dry zone’s home gardens.
Carbon sequestration
Carbon dioxide is the most commonly produced greenhouse gas and carbon sequestration prevents it from entering the Earth's atmosphere.
VTCSs contribute to carbon sequestration by storing carbon dioxide in their plants and soil and if managed strategically, have potential to further support climate change mitigation efforts in Sri Lanka.