Study Guide 1 Flashcards
. Briefly explain the planetary, geographic, physical/chemical, and biological factors
that determine the location of tropical ecosystems on the globe. In your answer,
provide the latitudes between which tropical forests occur
- “Tropics” dictated by tilt of earths axis, which determines where
incoming solar radiation is @ 90° - Solar radiation + evaporation of ocean H2O produce Hadley cells
- Hadley cells + earth’s rotation produce wind currents (northeast
and southeast trade winds) and maintain rainfall at equator - Trade winds + ocean currents distribute rainfall from east to
west - Location of continents alters ocean currents + ITZC to produce El
Niño events, which help regulate global temperature - Topography can alter precipitation and further limit actual
location of rainforests - Transpiration of water by plants also maintains atmospheric
moisture
Why do the paths of hurricanes never cross the equator?
- The paths of hurricanes never cross the equator due to the inter Tropical Convergence Zone
a. This is a zone of low pressure, about 5 degrees above and below the equator where the the northeast and southeast trade winds converge.
b. The Coriolis effect is also smallest here.
c. The sun causes moist, hot air to rise and go north or south
- Provide the climate and temperature conditions that define tropical lowland
(aseasonal) rainforests. In your answer, include approximate average annual rainfall
amounts, average daily temperature, and the range of average daily and yearly
temperature variation.
a. Mean temperature is ~25 – 26 C
b. 2-5 degree difference between coldest and warmest months
c. Mean temperature of coldest month is over 18 degree
d. Daily dif between min and max temp is <10 degrees (increases with eleation and latitude)
e. Mean annual rainfall is > 1500 mm and all months >100 mm (mega thermal is >2000)
- Approximately what percentage of the world’s forest cover is tropical forest and what
percent is tropical wet forests (e.g., not dry or deciduous rainforest)? Where does most
of that tropical forests occur (i.e., which area has the largest contiguous block of
rainforest)?
Tropical forests are 48-51%
Tropical wet forests are 32%
Neotropics (South America) has largest contiguous RF, then Old world tropics (Africa)
- List the seven major geographic regions of tropical forests. For each location, give an
example of a unique aspect of tropical forests in that region.
- Central & South America (isthmus of panama = cyclones; andes mts = stop rain from going west
- Africa (Congo basin RF maintained by transpiration; Rift valley traps wind from west and wind makes tropical savanna)
- Madagascar (steep plateau escarpment keeps rain in east strip; dry tropics in west) (too close to capricorn, so there’s cyclones)
- Southeast Asia (India/borneo used to be biggest trf; Mts stop rain from inland thailand and myanmar)
- India (west coast is abrupt cliff, so west is wet; close to cancer, so monsoons)
- New Guinea & Australia (new guinea is largest tropical island; Australia is wet and frost free in east)
- Islands of Oceania (volcanic mts and atolls; support trf bc of orographic rain)
How do Mexican forests differ from other Central American forests and what is their
biogeographic significance?
- way more spp because it ranges from subtropical to tropical (oaks and sweetgum are in the canopy)
- LOTS of ferns
What is the significance of the Darien Gap?
The darien gap is significant because it has insanely high rainfall- 3000-4000
- It’s a 106 km gap in the Pan American Highway that has a low level of disturbance due to the guerrilla forces (ELN, AUC, FARC)
- Also Choco and CUna indians
- lower level of disturbance –> no forest clearing
C. How do South East Asian Islands differ from
Why do the islands of Wallacea differ from nearby tropical regions in Southeast
Asia?
They were never connected to either the sunda shelf or the suhal shelf during any of the glaciation events
Why are African tropical rainforests less diverse on average than those of the
Neotropics?
- Drier (less rainfall) = energy for primary productivity
- medium energy, Africa is more diverse, but high energy africa loses
Not enough stable time? – inconclussive
less geologic activity? –> not necessarily bc there’s geographically complex regions in africa
extinction? nah, but lower rates of speciation
Human influence? maybe, but not enough evidence
What is meant by “disjunction” when discussing the distribution of taxa? Explain the
causes behind disjunct distributions and briefly explain each of the following types:
Austral disjunction, Amphi-atlantic distribution, Amphi-pacific distribution, PacificAmazon distribution.
Disjunction = geographical gaps in the distribution of a taxa
Causes: dispersal, extinction, radiation, coupled with vicariance, climate change, and biotic interactions
Austral disjunction: separation of Gondwana after origin of taxon –> Uraniidae in Australia, Madagascar, and South America
Amphi atlantic: either side of atlantic –> split of SA and Africa –> Papayas and bromeliads –> P felicia somehow in aftica
Amphi pacific: maybe climate change (boreotropical origins); maybe pacific zipper taxa
Pacific amazon: uplift of andes separated lowland amazon rfs from coastal equador and central america –> vegetable ivory palms
What was the Great American Biotic Interchange? What are some hypotheses for
why the interchange was asymmetrical?
- intermingling of north and south american faunas
- more north to south than south to orth
- possibly because carnivores led to the extinction of some of the animals in SA trying to cross
Tropical Dry and Deciduous forest
- how are the trees different?
- location?
- tree features?
- 5-7 month dry season (months where water lost by evaptranspiration is greater than rainfall)
- Taller trees and thicker bark
- closer to cancer or capricorn
- have lianas and buttresses, but not epiphytes and cauliflory
Deciduous forest locations
West coast mexico
costa rica
Dry forest locations
Costa rica: palo verde oak forests in Mexico Eastern Brazil almost all africa continental asia Panama NOT Sundaland
