Rinard Orchid Greenhouse Docent Program Week 3: Tropical Ecology

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1 Rinard Orchid Greenhouse Docent Program Week 3: Tropical Ecology

2 Objectives To introduce general concept of ecosystems Interrelating and interdependent communities are components of an ecosystem To provide knowledge of web of life & plant-animal connections To provide general understanding of tropical ecology To introduce concepts of human impact on tropical natural resources Photo credit: Cheryl LeBlanc

3 Ecosystem The network of interactions among and between organisms and their environment. Made up of all the living animals, plants and non-living matter in a particular place. All the living parts depend on all living and non-living parts for continued survival. Actions and reactions similar to a spider web. Any one part is connected and affects the whole ecosystem.

4 Web of Life Shows the interdependence within an ecosystem. Animals and plants depend on a complex system of food for survival. Example: In a typical prairie ecosystem: Sun provides energy for the grass; Mice, grasshoppers and birds feed on grass; Birds and frogs eat grasshoppers; Snakes eat birds, frogs and mice; Owls and hawks eat birds, snakes, frogs and mice. Decomposers, including worms, fungi and bacteria form a decaying process, to release nutrients to the soil for the grass to use again. All forms of life in the ecosystem are dependent on all other living and non-living things for food, nutrients and energy.

5 World Ecosystems Nine (9) major Ecosystems Worldwide

6 Tropical Rainforest Ecosystem Found around the equator. Temperatures stay near 80 o F year round. An average of inches of rain per year. Contain more than 1/2 of the world's 10 million plant, animal & insect species. Earth's oldest living ecosystem. The most productive & most complex ecosystem on Earth. Today, rainforests occupy only 2% of the entire Earth's surface, less than 6% of the Earth's land surface.

7 Rainforest Range and Diversity Largest rainforests Brazil (South America) Zaire (Africa) Indonesia (South East Asia). Hawaii, and the Islands of the Pacific & Caribbean Greatest diversity of tree species in the world. Main plants (70%) are trees. North America = 700 tree species. 700 tree species in one 25 acre area in Borneo!

8 Rainforest Ecosystem 80% of the rainforests nutrients stored in trees and plants. 20% of the nutrients in the soil. Nutrients instantly recycled into plant material. Very thin soils. Humus layer fragile, constantly recycled. When rainforest is cut, conditions change quickly.

9 Rainforest Structure Emergents - Tallest trees, +150 feet tall. Canopy Leaves shade below. Contains +50% of rainforest wildlife. Lianas (vines) reach canopy. Under-canopy Contains tree trunks and lianas. Shrub layer Receives only 3% of sunlight. Area of densest plant growth. Contains shadetolerant plants, saplings of emergents. Forest floor Dark, damp. Contains thin litter layer. Litter decomposes rapidly (< 6 wks), forms nutrient-rich humus.

10 Tropical Plant Structures Wide buttress roots - common in most trees. Buttresses - provide support for tree height ( ft) Tall - much competition for sunlight. Lianas (vines) - grow around trees to reach sunlight. Leaves - many are waxy Leaves - with drip tips to allow water to run off. Leaf shape - allows water to reach roots on forest floor. Leaf stems - flexible to move with the sun, maximize photosynthesis.

11 Slash and burn Human Impact Locals farm for 3-5 years = shifting cultivation. Sustainable method of farming on small scale Road Building - Ex: The Transamazon Highway. Logging million acres (5 million hectares) per year logged world-wide. Rainforest destruction, esp. in SE Asia and Africa. Cattle Ranching 2/3rds lowland tropical forests now pasture in C. America. Hydroelectric Power Large-scale Farming Nutrients exhausted from humus layer. Soil becomes infertile. Mining Iron ore, bauxite, gold, silver, oil and other minerals

12 Rainforest Connections Many trees & plants (incl. orchids) have been removed from the rain forest and cultivated. Banana - native to tropical Indomalaya and Australia, first domesticated in Papua New Guinea Coffee - native to tropical Africa, tropical Asia Cocoa native to tropics of Central and S. America Brazil nuts Brazil nut trees - only grows in undisturbed areas of Amazon rainforest. Pollinated by bees which also visit orchids Seeds are spread by the agouti, a small tree mammal.

13 Rainforest Representatives Tropical setting in Wheeler Orchid Collection & Species Bank Designed to suggest ecosystem connections Use orchids as teaching tools for tropical ecology Poison Arrow Frogs Rainforest mascots Show interconnectedness within a tropical ecosystem Photo credit: Cheryl LeBlanc