Disappearing wetlands – paddy fields
Geetha Iyer
What is a habitat? The Earth’s surface is inhabited by a huge variety of living creatures. They live in every available nook and corner and find newer places to live as they evolve. In order to know more about them ecologists and evolutionary biologists have divided the Earth’s surface with similar characteristics into areas called biomes. These biomes have been classified into several sub-groups that are termed habitats.
The word habitat is derived from the Latin word habitare meaning ‘it inhabits’. In other words, habitats are dwelling places for living organisms. They are therefore as varied as the animals and plants that live in them. Although diverse and varied, there are general principles that are applied to classify habitats in a biome. Both abiotic and biotic factors are considered when describing and classifying them. An interesting fact is that some of the naturally existing habitats have undergone modification due to human activities. One such example is the wetland some of which has been modified for the purpose of agriculture.
Wetlands
Wetlands are a distinct ecosystem. They are different from other aquatic ecosystems due to the presence of waterlogged soils and resultant characteristic vegetation. Since they hold water either permanently or seasonally, they provide a rich habitat for species to flourish. They also provide protection against floods, recharge ground water, process carbon, provide food and sustain biodiversity. Swamps, bogs, marshes and mangroves are a few examples of wetlands. Agricultural fields although evolved due to human activities also count as wetlands.
Paddy fields
Historically, agricultural fields were developed by draining wetlands. Agricultural practices, depending on their nature, have proved to be both constructive and destructive to the environment. It can be argued that the use of wetlands for agricultural purposes especially for the cultivation of crops such as rice is a better option as compared to their destruction for industrial or housing purposes. The choice of agricultural crop and processes practiced has some bearing on the health of these places. When plantations of commercial crops such as oil palms or rubber come up in a wetland then it is a matter of concern.
A paddy field (as opposed to a plantation) is a wetland that can sustain a significant biodiversity. About 90% of the world’s paddy fields are in Asian countries in places where monsoon is active. India has the highest cropland cover in Asia with about 43.65 million hectares under rice cultivation.
Paddies are a transient wetland where the characteristics of the habitat changes based on the amount of water present. This is one of the reasons for the presence of diverse life forms. Some of the fauna found in this habitat perform two significant ecosystem services for humans. They provide additional food security and protection against pests of rice. But there is a caveat. These services are possible only if the habitat is maintained through agricultural practices that are organic. The abiotic conditions that govern this habitat provide ecosystem services that conserve the environment, such as recharging the ground water and serving as flood control structures.
For rice to grow, the soil must remain waterlogged for a certain period of time till the paddy matures. This allows aquatic life forms to coexist with paddy and other plants. In places such as Kerala and West Bengal, the paddy field is a place to cultivate fish, crabs and prawns as additional food resource. The ‘bunds’ that surround the field are used to grow plants that serve as green fodder for animals and provide green manure for the agricultural system. In places like Kerala, medicinal plants have been found growing in these bunds. The biodiversity profiles change with the stages of paddy cultivation. Thus the ploughing season will see a different profile to that of the transplanting and growing season, which will again change when the field is ready for harvesting or after harvesting is complete and the field is left fallow. The paddy field thus functions as a system – an ecosystem – that allows diverse organisms, from microscopic to small and large to thrive.
Flora and fauna around a traditionally cultivated paddy field
Birds: A variety of birds may be seen and they vary from time to time between preparation of the field, to sowing and finally when ready for harvest. In a study carried out by Muhammad Jafer P of Calicut University, 29 species of birds belonging to 6 families were recorded by him. This included both residents such as egrets, ibises, pond herons, and migratory birds such as plovers, snipes and wagtails. Larks, pipits, sandpipers and even the endangered Saurus Crane and Black-necked Cranes can be seen in the rice fields of the Gangetic plains. In Japan, swans have been recorded flying to paddy fields. This is because there are irrigation ponds built near paddy fields to ensure that water can be made available if necessary. These ponds attract birds as paddy fields hold food sources such as insects, worms, fish, etc.
Invertebrates: Insects, spiders, crabs, snails, clams. Paddy is a food not only for humans but also for a number of insects. In addition to grasshoppers, beetles and bugs , caterpillars are a big headache for farmers. But there are also other insects for whom the paddy-harming insects are food sources. Dragonflies can be seen foraging on plant pests. At least eight species of dragonfly and five species of damselflies have been recorded from the paddy fields of Palakkad. They are a farmer’s friend and help in keeping a check on plant destroying insects. Similarly, spiders also serve to control plant pests. Annelid worms and several molluscs may be found in the paddy fields, which also support a sizeable population of crabs and shrimps. Several invertebrates that are small and difficult to locate live here serving as food for the larger invertebrates and vertebrates.
Other vertebrates: Standing water in the paddy fields attracts a number of vertebrates – some take temporary shelter, for some it’s a habitat for producing their young and for others a permanent place to live. Thus frogs and snakes may be spotted. Fish are cultivated in paddy fields.
Studies of biodiversity of paddy fields have revealed that in Southern India paddy fields support 57-149 bird species, 24-30 odonates (dragon and damselflies), 41-51 species of butterflies and up to 169 plant species.
Threats to paddy fields
Paddy fields are slowly disappearing. This is because of the decline in paddy cultivation. Farmers no longer have access to seeds that were traditionally cultivated which gave them good returns. Today the cost of raising a crop is high and returns are poor. Erratic climatic conditions, labour shortages, increased costs and diminishing returns have resulted in paddy cultivation being unsustainable for the farmer. They then opt for conversion of paddy fields into plantation crops or sell the land to the ever increasing demand of housing projects. This results in the loss of a well-developed and complex wetland agro-eco-system. This disruption of a fragile ecological balance affects those who are dependent on land for their livelihood.
What can be done to conserve them? Practices adopted by farmers shape agricultural ecosystems and the biodiversity within. They need to be supported to ensure adequate returns for their efforts. Generations of humans, through a process of trial and error, have learned to maintain a sustainable agricultural field. Keeping traditional knowledge alive and building on them through knowledge gained by scientific advancements is important to save such habitats from destruction. Listening to an experienced farmer is as important as listening to what scientists have on offer. Whether laboratory modified varieties of paddy, cotton or wheat should be introduced is an argument that will have a significant bearing on the wetland ecosystem. But the voice of a farmer is not heard. Till those who till the land are not part of the discussion on what is to be grown and the nature of support to be given, the ecosystem will suffer and the cost of its decline will never be noticed till it is too late.
Paddy facts
- 50,000-60,000 varieties of rice were cultivated in India once upon a time.
- ‘Navara’, a medicinal rice variety, is used in Ayurveda for treating paralysis and muscle wasting.
- Pokkali is a cultivation method where paddy and prawns are grown alternatively. Pokkali rice plants are salt resistant.
- A farmer in Hatia village of West Bengal grows 36 types of brinjal, 8 types of okra, 6 varieties of pulses in his paddy field.
- Reference to black rice is found in Sangam literature.
Classroom Project. Grade 8
Environment Science
Growing paddy to learn about conserving a habitat.
Materials needed: A rectangular tray that is not shallow or clay pots; a small clay or plastic cup; paddy seeds; compost and soil; water.
Conversation with a farmer to familiarize with the processes will be useful.
Mix soil and compost and fill 2/3rd of the tray/pot with it.
Fill the clay cup with the same soil mixture. Sow the seeds. The seeds will germinate in the clay cup. Find out if the seeds need any treatment before sowing.
Raise the seedlings in the clay cup and then when they grow to about 6-8 inches high, carefully remove them and transplant them into the tray. Ensure that the soil in your tray is sufficiently watered.
Find out how frequently manure has to be added and follow the procedure.
Observe the growth and make note of the ‘visitors’ to your “paddy field”.
Discuss periodically your observations of the events taking place and about the results of your cultivation.
What did your experiment yield? What did you learn about the paddy ecosystem?
A visit to a paddy field and a talk with a farmer will prove to be useful before this experiment is undertaken.
References
• https://www.downtoearth.org.in/news/agriculture/agroforestry-boosts-rice-and-biodiversity-in-india-59377
• https://tinyurl.com/tbvwlec
The author is a consultant for science and environment education. She can be reached at scopsowl@gmail.com.
