Lecture 1: Introduction

Question 1

Where are the tropicS?

Answer 1

23.4 degrees both North & South of the equator

Question 2

temperature in the tropics:

Answer 2

minimal variation throughout the year and diurnally (during the day)

Question 3

tropics mainly dry/wet?

Answer 3

• mainly wet! : rainforest >2m rainfall yr^-1

- wetter and drier seasons

Question 4

basic Structure of trocial forest (2 levels)

Answer 4

• tall: lots of sun

- Dense dark undergrowth

Question 5

who do tropical forests vary?

Answer 5

1) continental variation
2) hydrology
3) altitude
4) rainfall

Question 6

Continental variations:

Answer 6

• the amazon
• the congo
• Borneo
• –> different species in different areas

Question 7

hydrology variation e.g. Amazon

Answer 7

• Terra firme - dry

- Varzea - flooded for some time in year

Question 8

hydrology variation e.g. Borneo

Answer 8

• Dry dipterocarp

- Peatswamp

Question 9

Altitude variation:

Answer 9

-in the Andes 
BOTTOM 
-amazon rainforest 
-subtropical cloud forest 
-icy mountain tops
-TOP
species vary at different heights

Question 10

rainfall variation: Andes:

Answer 10

• rainfall comes in from the east from atlantic ocean, rains over THE AMAZON
• mountain block rain access to West –> Tumbesian dry forest (C. 800mm rainfall per year)

Question 11

other tropical dry forests:

Answer 11

• eastern Kenya/ Tanzania
• Western Madagascar
• Indochina

Question 12

why do tropical forests matter??

Answer 12

• most species on earth!
• enigmatic wildlife
• most endemic (restricted range) species
• highest densities of species on earth
• typified by complex networks of interactions
• provide key ecosystems services

Question 13

how would you describe the diversity in the tropics?

Answer 13

HYPERDIVERSE

• tropical forests have huge DENSITIES of species
• 1 hectare can have 650 tree species
• 7 hectares in SE Peruvian Amazon has 600 birds species

Question 14

networks of interactions:

Answer 14

• rainforests typified by complex networks of interactions between species
• predation (e.g. largepredators exert top down effects on smaller predators)
• nutrient cycling
• plant pollination by insects, birds & bats
• seed dispersed by birds & mammals
• symbiotic relationship where species live together & trade benefits

Question 15

example of symbiotic relationship in the tropics

Answer 15

“Devil’s” gardens
-Clearings in forest dominated by 1-2 species of ant-plant
Duroia hirsuta plant provides Myrmelachista schumanni ants with housing in domatia
Some Devil’s gardens get very large
594 D. hirsuta trees
15,000 queen & 3 million worker ants
Colonies can live for 800 years

Question 16

how do the locals think Devils gardens arise?

Answer 16

• “spirit clearings” are invisible villages of spirits

- Swollen trunks surrounding clearing caused by fires set by spirits for swidden gardens

Question 17

Real reasons for Devils gardens

Answer 17

• galling by ants
• -trees swollen trucks due to the trees inhabited by M. schumanni workers, brood and queens
• -71% of trees around clearing had gals
• -M. schumanni severely nest site limited
• Cultivated by ants?
• -M. schumanni workers kill other understored plants by injecting them with formic acid
• Creates clearings in which host plant thrives
• Selective advantage for host ant-plants

Question 18

Ecosystem service definition:

Answer 18

the provision of a natural resource of process that is valued by humankind - Edwards et al. 2014 Trends Ecol Evol

Question 19

examples of rainforests & ecosystems services:

Answer 19

• Carbon storage (mitigates climate change)
• Wood, fruits & animal protein
• Hydrological services
• -rainfall and temperature control
• -erosion & flood protection

Question 20

Tropical forests are under

Answer 20

THREAT - Global Biodiversity Crisis

Question 21

global biodiversity crisis:

Answer 21

• decrease in birds, mammals, birds & amphibians
• increase in extinction rates
• -distant past 0.1/1000 years
• -recent past 100/1000 years
• man is causing the 6th mass extinction, the only biologically driven one

Question 22

whats new with this mass extinction:

Answer 22

the only biologically drive one

Question 23

where is mass biodiversity loss?

Answer 23

IN THE TROPICS

Question 24

____ are driving a biodiversity crisis

Answer 24

humans

-biodiversity loss is most severe in tropical rainforests

Question 25

major drivers of biodiversity crisis:

Answer 25

Forest loss (farming & fragmentation), degradation (logging), and hunting are the major drivers