Week 1 Lecture Notes – 30 Aug. 2012

Pre-Quiz for extra credit

Intro to tropical ecology

There are many types of tropical ecosystems – tropical forests occupy 7% of earth’s surface, but include 50% of the world’s biodiversity!

Biodiversity = Biological richness of an area, usually defined as the number of species.  Example: 3 doves, 5 parrots, 2 woodpeckers = diversity of 3.

Tropical rainforests – 57% are located in the Neotropics (Western Hemisphere). (30% of the world’s rainforests are in Brazil) – See Figure 52.5.   

At the current deforestation rate, in 177 years all tropical rainforests will be gone.  We will find out what that means for the rest of the earth as we learn about the functions of rainforests and other tropical biomes.

Before we continue, let’s talk about what ecology is. 

Ecology = The scientific study of the interactions among organisms and between organisms and their environment. 

Living organisms can be grouped together into communities – all the organisms in an area.

Example - Aquatic community = frogs, egret, fish, dragonflies, turtles, aquatics plants such as cattails, reeds.  What separates this from other communities?  The ecosystem.  A forest community is different = woodpeckers, tako (cuckoos), beetles, tree snakes, tarantulas, palm trees, ferns, etc.

Ecosystem = the system embracing the organisms plus their physical environment.

Environment is composed of both biotic – living, biological things & abiotic factors.  – chemical and physical   examples = water quality, temp etc.

Why should we care about all this?  Ecosystems provide goods and services people need.  List some examples:  Clean air & water, timber, food, fertile soil, etc.

Geography – where are the tropics?

Know these terms - Latitude and longitude, Eastern & Western and Northern & Southern hemispheres.  Equator is at 0 degrees latitude.  Prime meridian is at 0 degrees longitude (runs through England)

Tropic of Cancer = 23˚ 27’N and the Tropic of Capricorn = 23˚ 27’S.   

This is read as 23 degrees, 27 minutes north or south.

Here the sun is overhead all year.

Earth is tilted at 23˚ 27’!  Therefore in Northern Hemisphere the sun is overhead in June 21 – Sep. 21, and in Southern Hemisphere the sun is overhead Dec. 21 – Mar. 21.

Sun’s radiation falls most directly & most constantly upon the equator.

Area between latitudes 23˚ 27’ N & 23˚ 27’ S = TROPICS!

Equal time of sun at equator = 12 hr

Relatively consistent temperature all year.

Farther north and farther south you go from the equator, the more oblique the sun’s rays become.  Therefore:  Day length differs throughout the year.

Temperature differs throughout the year (therefore seasons).

Biomes are terrestrial environments defined by the growth forms of its plants.

            They are influenced by geography & climate, & determined by plants!

They are influenced by annual precipitation & temperature which vary throughout the year.  See Life Fig 52.5.

Fig. 52.5 Biomes of the world.

 

Tundra

• arctic & high elevations of mountains. 
• soil frozen, low growing plants with growth a few months a year, animals migrate or hibernate
• temperature -25C to 5C    (-13F to 41F)
• 23 cm precipitation = 2 inches

Temperate Deciduous Forest

• Eastern US
• Wide flux in temperature winter to summer  -5C to 30C (23F to 86F)
• 81 cm precip  snow and rain
• Trees loose leaves in winter

Temperate Grassland

• Central US
• Wide flux in temperature winter to summer  -5C to 35C  (23F to 95F)
• 31 cm precip snow and rain
• Grasses and forbs (herbaceous plants), few trees = AGRICULTURE

Desert – Cold

• Southwest US
• Wide flux in temperature winter to summer  0C to 25C (32F to 77F)
• 38 cm rain
• shrubs

Desert – hot

• Mexico
• Narrow range of temperature 25C to 35 C (77F to 95F)
• 15 cm rain!
• Succulent plants – cactus

Thorn Forest and Tropical Savannah

• Edge of hot desserts, on the tropical side
• Narrow range of temperature 25C to 35 C (77F to 95F)
• A lot of rain  74 cm
• Spiny shrubs, small trees loose leave during dry winter.  Where it is grazed by large animals we have savanna – grasses with scattered trees.  – AFRICA with giraffes, antelope, etc.

Tropical Deciduous Forest

• Move towards equator and replace above biome with this biome
• Narrower range temp 22C to 27 C
• Even more rain 163 cm
• Most trees loose leaves during dry season
• Rich soils, thus have been cleared for agriculture

Tropical Evergreen Forest – Haiti

• Move towards equator and replace above biome with this biome
• Even narrower range temp
• Even more rain >250cm
• Highest in biodiversity, and more epiphytes (plants that derive moisture and nutrients from air and water rather than soil)
• Poor soils since most nutrients are tied up in the vegetation

Homework assignment: Read Article 1 about the Macaya bird survey and write a one page paper answering:

1.      Purpose of the study (why)

2.      When and where the study took place

3.      How the researchers captured the birds

4.      List 2 results of the study

5.      List the conservation recommendations

(Rimmer, C.C, J.M. Townsend, A.K. Townsend, E.M. Fernández, and J. Almonte.  2005.  Avian Diversity, Abundance, and Conservation Status in the Macaya Biosphere Reserve of Haiti.  Ornitologia Neotropical 16: 219–230.)