Study Guide 1

Question 1

. 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

Answer 1

1. “Tropics” dictated by tilt of earths axis, which determines where
   incoming solar radiation is @ 90°
2. Solar radiation + evaporation of ocean H2O produce Hadley cells
3. Hadley cells + earth’s rotation produce wind currents (northeast
   and southeast trade winds) and maintain rainfall at equator
4. Trade winds + ocean currents distribute rainfall from east to
   west
5. Location of continents alters ocean currents + ITZC to produce El
   Niño events, which help regulate global temperature
6. Topography can alter precipitation and further limit actual
   location of rainforests
7. Transpiration of water by plants also maintains atmospheric
   moisture

Question 2

Why do the paths of hurricanes never cross the equator?

Answer 2

2. 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

Question 3

3. 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.

Answer 3

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)

Question 4

4. 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)?

Answer 4

Tropical forests are 48-51%

Tropical wet forests are 32%

Neotropics (South America) has largest contiguous RF, then Old world tropics (Africa)

Question 5

5. 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.

Answer 5

1. Central & South America (isthmus of panama = cyclones; andes mts = stop rain from going west
2. Africa (Congo basin RF maintained by transpiration; Rift valley traps wind from west and wind makes tropical savanna)
3. Madagascar (steep plateau escarpment keeps rain in east strip; dry tropics in west) (too close to capricorn, so there’s cyclones)
4. Southeast Asia (India/borneo used to be biggest trf; Mts stop rain from inland thailand and myanmar)
5. India (west coast is abrupt cliff, so west is wet; close to cancer, so monsoons)
6. New Guinea & Australia (new guinea is largest tropical island; Australia is wet and frost free in east)
7. Islands of Oceania (volcanic mts and atolls; support trf bc of orographic rain)

Question 6

How do Mexican forests differ from other Central American forests and what is their
biogeographic significance?

Answer 6

• way more spp because it ranges from subtropical to tropical (oaks and sweetgum are in the canopy)
• LOTS of ferns

Question 7

What is the significance of the Darien Gap?

Answer 7

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

Question 8

C. How do South East Asian Islands differ from

Question 9

Why do the islands of Wallacea differ from nearby tropical regions in Southeast
Asia?

Answer 9

They were never connected to either the sunda shelf or the suhal shelf during any of the glaciation events

Question 10

Why are African tropical rainforests less diverse on average than those of the
Neotropics?

Answer 10

• 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

Question 11

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.

Answer 11

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

Question 12

What was the Great American Biotic Interchange? What are some hypotheses for
why the interchange was asymmetrical?

Answer 12

• 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

Question 13

Tropical Dry and Deciduous forest

• how are the trees different?
• location?
• tree features?

Answer 13

• 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

Question 14

Deciduous forest locations

Answer 14

West coast mexico

costa rica

Question 15

Dry forest locations

Answer 15

Costa rica: palo verde
oak forests in Mexico
Eastern Brazil 
almost all africa
continental asia
Panama
NOT Sundaland

Question 16

Tropical wet savannas

Answer 16

• occur in floodplain regions <150 m or geological depressions that accumulate water
• water rises 3 m during rainy season

-perrenial grasses and aquatic plants
-trees are sparse or absent
grasses can get 3 m high

Pantanal in Brazil, Bolivia and paraguay 1000-1500 mm

Venezuelan Llanos 2000-3000 mm

Question 17

Tropical dry savannas

• how many dry months?
• how much rain?
• vegetation?
• soil
• examples

Answer 17

low altitude

• 4-8 dry months
• 1000-2000 mm
• xeric grasses and sedges
• low trees and shrubs
• lighting fires
• dry,sandy, or clay soil

Carib pine savana in belize
tasistales savanna in mexico
woodland savanna (cerrado) in brazil
African Serengeti-mara

Question 18

Tropical cloud forests

Answer 18

-elevations:
lowland montane 1200-1500
cloud > 1500
elfin > 2800

rain: 2000mm

temp goes down, but variation goes up
-canopy gets shorter
lianas replaced by moss and bryophytes
-more epiphytes
-more gymnosperm
over 2500 m leaves go from mesophyll to microphyll

Borneo
Australia

Question 19

Tropical monsoon forests

• terrain?
• rainfall?
• tree features?
• plant types?
• where?

Answer 19

lowland and montane areas with rainfall >2500 mm and most rain concentrated within a few months

thicker bark, less lianas, lower canopy

bamboo, palms, cane

indian ghatts

Question 20

Tropical peat forests

Answer 20

flooded areas with poor drainage
-no dry season
rain >3500
form concentric circles
thick peat in center supports notophyll vegetation
low canopies

borneo

Question 21

Tropical heath forests

Answer 21

-grow on well drained, white sand soils
-ph < 4
rarely big trees –> low canopy
-rarely lianas
-sparse ground vegetation (mosses, liverworts, and carnivorous plants)
-rarely vertebrates

kerangas in borneo
campinara in venezuela
campina in guyana
Eastern Rift

Question 22

Monodominant tropical forests

Answer 22

Regions of old growth where 1 spp is over 60% of canopy
many kms
forsets still have lots of spp
-either super dry or super wet areas
-areas of low disturbance

palm forests in puerto rico, brazil, and triidad
mimosoid forests in costa rica 
pine forests in guatemala
shorea forest in borneo
legume forest in congo

Question 23

Tropical shola forests

Answer 23

-over 1700 m
patches of high elevation elfin forest in mountain valleys between grasslands
-heavily branched, stunted trees
dense canopy
lots of epiphytes
-sharp boundary bt forest and grassland

India

Question 24

Tropical thorn forests

Answer 24

• deciduous/ semi deciduous tropical broadleaved forest
• low altitude
• discontinous layer of low tree and shrubs
• thorny plants
• no grass usually
• low canopy
• white sandy soil

Brazil

Question 25

``` What kind of forests are these? Tepuis Cenotes Cerrado Pantanal Caatinga Llanos Kerangas Eastern Arc Rift Zone forests Serengeti-Mara Savanna Dipterocarp forests ```

Answer 25

``` Wet tropical savana Tropical Rain Forest? Tropical Dry Savanna Tropical wet savanna Tropical thorn forest Wet tropical savanna Heath Forest Dry forest dry savanna Dipterocarp ```

Question 26

What is the relationship between elevation and the height of a forest canopy? That is, how do high elevation forests differ from lowland forests in structure?

Answer 26

The higher the elevation, the lower the forest canopy - less lianas - more epiphytes and gymnosperm - smaller leaves

Question 27

Do tropical forests show “vertical stratification”? In your answer, explain the types of evidence that ecologists have used to determine if more strata exist in tropical forests than in other types of forests. What factors are important in dictating the number of layers that exist in a forest and does this explain why there may be more layers in tropical forests (i.e. explain how the angle of sunlight determines tree shape and canopy layers. You may draw diagrams if necessary.)?

Answer 27

Yes Supporting evidence: several layers are observed; dif spp mature at diff heights; some spp stay in a single layer -Sympoidal trees allow for more light to get through to other layers -Shape of crowns and gaps between trees and physics of light derive pattern of stratification -Zero spacial variance zone gets sunlight at least once a day --> THAT's where next strata layer will be Ground Understory Canopy Emergent

Question 28

What are some plant adaptations specific to tropical forests? Give examples for all plant parts (crowns, boles, roots, bark, leaves, flowers, fruits). What types of adaptations do tropical plants have that allow them to adapt to high light environments?

Answer 28

Crown: sympodial growth - wide and flat for self shading - crown shyness Boles: thick wood that tapers so can be tall with less wood Roots: buttresses (conduction short cut), prop roots, few thick deep ones Bark: super thin and smooth for shedding; often colored and may be armed with physical or chemical defenses Leaves: waxy pointed, oval, thick, smooth margins, drip tips, anti herbivore stuff Flowers/fruits: grow off stems --> maybe use fauna that live near ground, sturdy and well-attached

Question 29

What are some hypotheses for the existence of buttresses?

Answer 29

1. Phylogenetic: depends on strain from wind --> nonfixed 2. Adaptation to wind and gravity of location --> fixed 3. Negative geotropism --> seeds grow against gravity 4. conduction shortcut: get water all the way to the canopy

Question 30

. How do tropical forests compare to temperate forests in terms of numbers of trees per hectare? What is the relationship between Neotropical, African, and Southeast Asian forests in terms of plant diversity?

Answer 30

- 100-300 trees per hectare in tropical forest; 15-20 in temperate - Neotropics: Asian-Pacific: African = 3:2:1

Question 31

what are the pantropical plants?

Answer 31

Rubiaceae, Piperacaea, Moraceae Fabacea, Orchidaceae, Bromeliaceae

Question 32

Rubiaceae - Stats - oriigins - examples - key charactristics

Answer 32

- 4th biggest fam of angiosperms - originated 90 mya - Coffea and Cinchona and calycophyllum - dispersed by birds - glossy simple opposite leaves - small, tubular flowers with bright sepals or bracts - leaf nodules with bacteria - kissing lips - trends indicate bee trends

Question 33

fabaceae - stats - where? - when did it enter fossil record? - examples - key characteristics

Answer 33

- beans, legumes, peas - 3rd bigest angiosperm fam - dominate african and neotropical forests - 55 mya - macuna, entada gigas, bauhinia, indigofera, lianas - modified flowers with banner and keel - pod-like fruits - pinnate leaves - rhizobium bacteria

Question 34

Piperaceae - where in forest strata - animal associations - key characteristics

Answer 34

- black pepper (piper nigrum), kava, betel - high diversity in tropical understories - several species with ant mutualisms "myrmecophyte" - spike inflorescence - pea-sized peppercorn fuit - swollen nodes

Question 35

Moraceae - what is it mainl important for - animal association - key characteristics - significant life form

Answer 35

- figs - year round fruit - resource for fruit-feeding animals (40 per plant) - coevolved with pollinating wasps - simple leaves - minute, clustered flowers - latex - synconium flower (inside) - Hemi epiphyte: strangler fig

Question 36

Bromeliaceae - main life forms - origin - animal interaction - Key characteristics - examples - growth forms

Answer 36

- epiphytes and lithophytes - Andean Tepuis - Phytotelmata= water filled cavity for aquatic insects - monocots with rosette foliage - colored leaves or bracts - stalked flowers - stiff or spiny leaves - Tillandsia and Alcantarea - Tank bromeliads, ant associated bromeliads, air plants

Question 37

Where would we find Dipterocarpaceae and, besides being restricted to Indian and Southeast Asia regions, how does this family of plants differ from the five you’ve just described?

Answer 37

Its in Thailand, Borneo, and New Guinea - It is a monodominant species - found in mountainous areas

Question 38

. What type of “lifeform” is a liana? Describe where you are most likely to find lianas and why.

Answer 38

-Woody climbing plant/ vine -grow from ground level into canopy Found around trees bc they latch on -You'll find them in the tropics because their wide vessels for carrying water would freeze if they were in an area that wasn't warm enough

Question 39

Describe and give examples of the different types of tropical plant life forms, including epiphytes, hemi-epiphytes, woody monocots, and epiphylls.

Answer 39

Epiphytes = plants that grow on or attached to another plant without havind roots in soil --> not parasitic--> bromeliaceae, orchindaceae, cactaceae, piperaceae Hemi-epiphytes: begin growth in upper canopy, roots go down, then plant grows more --> strangler fig Woody monocots: have vascular bundles (not continuous layer) creating xylem and phloem; perenial; above ground; fibrin and lignin --> palms (Aracaceae) Epiphylls