Teachers’ Lounge

Biodiversity on the Plantation

by megan on Nov. 21st, 2008 No Comments

You may have heard how tropical rainforests support over 50% of the planet’s biodiversity (the variety of life that lives in a particular place). When one considers the threats to rainforest creatures worldwide, loss of habitat is often at the top of the list. The majority of this habitat is lost due to an expanding human population. When houses are built, roads are constructed, or land is converted to agriculture, local wildlife inevitably loses a home. Or not?


Photo credit: deepsan
Jai Ranganathan and his colleagues down at Stanford University published an article this month in the Proceedings of the National Academy of Sciences describing a survey of bird diversity in areca palm plantations in south-west India. The betel nut and leaves of the areca palm are used throughout Asia in medicine, and commonly chewed to enjoy a coffee-like stimulant. The betel nut grows in the canopy of tall, lush trees, so cultivating this crop provides habitat for large forest birds, such as the great hornbill (Buceros bicornis). When surveying the plantation’s species richness (the number of different species in a given area), scientists discovered that as much as 90% of the birds living in the native forest also found suitable habitat on the farm.

Tall areca palms (above) grow betel nuts, which provide food for hungry great hornbills (below). Better yet, farmers have room to plant diverse crops below the canopy. These shorter plants, in turn, host an increased variety of bird life.

Photo credit: Lip Kee

Two factors contribute to the success of areca nut plantations:

  1. Because the palms are so tall, they can plant shorter species in the space below. Economically valuable crops such as vanilla, pepper, bananas, and coconuts grow at varying heights, from the floor up to the understory. Because of this structural complexity in forest layers, many more bird species can find a suitable habitat (food, water, and shelter!).
  2. Rather than using chemical fertilizers (both expensive and harmful to the environment), farmers care for their crops the natural way. They collect spare leaf litter from nearby forests, and blanket the ground with a coating of nutritious mulch.

The authors argue that the areca nut plantations — cultivated for 2,000 years by local farmers — may serve as a model for conservation efforts in similar habitats.

Some questions for class discussion:

  1. How does an areca nut plantation support rainforest wildlife?
  2. How does an areca nut plantation support the farmers in India?
  3. Which do you find more important: the ecological value of a rainforest habitat or the economic benefits gained by local human communities?
  4. Where else do you think farmers should copy this method of agriculture?
  5. Picture your perfect farm — one that provides your family with plenty of produce, yet also leaves room for wild plants and animals. Create an illustration individually, in groups, or as a class, and explain the reasoning behind your plantation’s plan.

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