Students will be able to:
1. Define the vocabulary terms tree and habitat.
2. Identify five species of animals that live in American Samoa's tree habitat.3. Describe how our actions can threaten the health of our trees.
One of the significant characteristics of tropical rainforests is high species diversity. Tropical rainforests are home to the majority of the world’s plant species. The flora of Samoa (the sum of the plants occurring in the archipelago) comprises about 550 native flowering plants, 215 fern species, and 13 fern ally species. About two thirds of these species are found in American Samoa. They can be divided into two types: endemic species (restricted to Samoa) and indigenous species (not restricted to Samoa).
The level of endemism of the native flowering plants in Samoa is estimated to be about 30% at the species level. Areas to the west such as Indonesia and Malaysia have much larger floras, a characteristic that can be attributed to their much larger areas, older age, and to what is called a “filter effect” in which chance and distance limit the number of species successfully reaching (and becoming established in) the faraway islands of Polynesia.
Another characteristic of tropical rainforests is the presence of unusual life forms. One of the most unique is that of epiphytes, plants that grow on trees, usually in order to get closer to the sunny canopy, but which do no harm to the “host” plant. When the conditions in the forest are extremely wet, as they are in the montane forest and cloud forest, epiphytes may even cover the trees. The most prevalent group of epiphytes is the orchid family, which comprises 65 species in American Samoa (many of which are not epiphytes but grow on the forest floor). Epiphytic ferns comprise the second most abundant group of epiphytes in the Territory.
The vegetation of Samoa is not homogenous, because zones of plant combinations can be discerned. It is difficult, however, to make sense of the differences we can see in the pattern of plants, and even more difficult to determine where the boundaries are between the different types of vegetation. The vegetation can generally be divided into a number of categories called “plant communities.” A plant community is a unit of similar vegetation distinguished from other plant communities by its structure and habitat. Eight natural plant communities can be recognized in American Samoa: (1) Littoral Strand, (2) Marsh, (3) Freshwater Forest, (4) Mangrove Forest, (5) Lowland Forest, (6) Montane Forest, (7) Montane Scrub, and (8) Summit Scrub. Several other disturbed types of vegetation can also be recognized.
Littoral Strand comprises the forest, scrub, and herbaceous zones growing directly on the seashore. Its component species are seawater dispersed and widespread on Pacific shores. Marsh, Freshwater Forest, and Mangrove Forest are classified as “wetlands,” but they comprise only a small percentage of the overall land area of American Samoa. Lowland and Montane Forest together comprise the “tropical rainforest” that once covered over 90% of Samoa.
Montane Scrub and Summit Scrub are unique. Montane scrub comprises the vegetation on the summits and upper slopes and ridges of Tutuila on geologic areas called “trachyte plugs,” which have a characteristic chalky soil that appears to cause stunted vegetation. Its scattered, stunted trees are embedded in a dense matrix comprising shrubs, ferns, and lianas. Epiphytes also abound in this community, sometimes covering the stunted trees.
A plant community that is in equilibrium with its environment, when its form and flora change little with time (barring major disturbance), is called a “climax plant community.” A climax forest is often confused with “primary forest,” which is the natural and undisturbed forest in an area. However, nearly all of the mature forests in Samoa are better described as climax rather than primary forest, since in ancient times much of the interior of the islands was inhabited and cleared for cultivation before being abandoned early in the European Era (after 1830).
Native tropical forests serve several important functions in American Samoa and throughout the tropics. First, they provide protection from soil erosion, which leads to a higher quality of drinking water. Second, they are home to a majority of the world’s plant and animal species. Third, they serve as home to animals, such as pigeons and flying foxes, and plants, such as Tahitian chestnut (ifi), that have traditionally been a major part of the local diet.
Unfortunately, the forests of American Samoa are seriously threatened. The most dangerous threats, direct or indirect, are the actions of people. Due to rapid population growth, the existence of communities such as mangroves, wetlands, and some kinds of lowland forest have been nearly eliminated. Alien plant and animal species also threaten to outcompete and reduce the abundance of some native species.
1. Large piece of white paper, 15 ft. x 3 ft. wide.
4. Chalk or whiteboard
5. Duct tape
7. Paint brushes
8.Tasi's Gift by Tamara Montgomery
Introduce Inquiry Questions
What is a tree? What types of trees exist in American Samoa?
Ask: What are trees? Are they living things? What makes them living things? Explain that trees are a habitat for many other living things like birds and fruit bats. Tell students that trees show a high level of diversity in American Samoa. To illustrate the concept of trees, show students the images of the National Park of American Samoa’s native rainforest.
Activity 1: Tasi’s Gift
1. Read story to students.
2. Questions after story reading: Who is Tasi and what does her father do for a living? What type of tree in the rainforest was used to make the bowl? What is the significance of that tree to Samoan culture?
Activity 2: Tree Cut Out
Have students gather into groups in different areas of the classroom. Distribute one piece of large to each group. Students can work on the floor or on tables. Have one student lie down on the large paper with their arms extended while other students use pencils to trace their.
Instruct students that they are going to use scissors to cut out the image of the student they drew on the large piece of paper. Assign group members to take the paint and use their paint brushes to color the image on the large piece of paper. Use green paint to color the head, brown for the body, and a mixture of the two for the arms. In the end, students will have a cut out of a tree. Students should also paint what other living things they might find living on a tree. i.e. birds, fruit bats, geckos, etc. Caution students to be careful when handling paint and scissors.
Direct groups to name their masterpiece and write their names at the bottom of the cut out. Ask them to gently use the duct tape to attach their cut outs onto the chalk or whiteboard. Each group will present their cut out, explaining what trees are and what they’ve learned so far.
Conclusion with Inquiry Questions
What is a tree? What kinds of trees exist in American Samoa?
Encourage your family and friends to plant trees around your home and in your community. Talk to them about the various uses for trees in American Samoa.