Threats to Tropical rainforest biodiversity

Question 1

What is Forest degradation >

Answer 1

Alteration of forest by human activities without complete deforestation.

Question 2

Why can agriculture only be practiced for a limited time in one area?

Answer 2

Rainforest soils are very nutrient-poor with high rates of decomposition, this means any crops will quickly leach any nutrients from the soil.

Question 3

What is an old-growth forest>

Answer 3

Never been cut or cleared by humans.

Question 4

What is a degraded forest?

Answer 4

Altered by human activities

Question 5

What is a managed forest?

Answer 5

Actively managed for human benefit.

Question 6

What is a secondary forest?

Answer 6

A forest regenerated after complete deforestation.

Question 7

What species are most vulnerable to fragmentation (not specific species - but traits)

Answer 7

Large predators/megafauna which require large areas.
species reluctant to cross small gaps
Specialists in forest interior habitats - often require more than 3-4 ha and are reluctant to cross roads greater than 30m.

Question 8

What are the short-term consequences of forest fragmentation?

Answer 8

Large mammals migrate away
Small non-flying mammals increase
Primate species richness declines
Bird biodiversity initially increases then dramatically declines.
Dung beetles decline
Euglossine bees will not fly between fragments which reduces pollination.

Question 9

What are the long-term consequences of fragmentation?

Answer 9

Absence of seed dispersers and pollinators
Prevention of species reproducing
long-term change in community composition.

Question 10

What is matrix sustainability?

Answer 10

Provides connectivity between forest fragments.

Question 11

What are edge effects?

Answer 11

The recolonizations of fragmented forest edges by successional tree species.
Seed rain from surrounding matrices containing successional species can prevent further edge effects and allow recolonization of the same forest species when successful species die.

Question 12

What is a secondary forest?

Answer 12

Pastures abandoned within a few years of deforestation.

Question 13

What are the impacts of fire-positive feedback?

Answer 13

Initial fires tend to be of low-intensity
Burns the understory only m
Kills off thin baked trees opening up canopy
raises temperatures dries leaf litter and adds combustible material.

Question 14

How is climate change affecting deforestation?

Answer 14

Brings high temperatures and drought
increases the frequency of fires in El Nino years.

Question 15

What species are most sensitive to logging?

Answer 15

Evolutionarily ancient that evolved in the Miocene or early Pliocene.

Question 16

What are the consequences of overhunting for forest community composition?

Answer 16

Large frugivores tend to be targeted, this reduces seed dispersal which decreases overall tree species richness. The density of plants dispersed by megafauna decreases as well.