L2 Flashcards

Question

Competitive exclusion

Answer 1

- Species that lack adaptations but are competitive outcompete specialists - Cold or dry species are excluded from warmer, wetter climates by competition

Answer 2

- Roles of climate and soils in determining biome distributions - Emphasis on forests as potential and most important vegetation - View of open landscapes as being degraded by fires and deforestation - Lead to ideas that open landscapes being degraded landscapes?

Answer 3

- Tree-grass coexistence - Continuous ground layer of grasses and varying tree cover - Grasses are C4 as in hot environments

Answer 4

- Deforestation and fires in tropical forests can lead to savanna-like vegetation - Often referred to as 'savannisation' - This looks like savanna according to its definition but is not

Answer 5

No it looks like savanna but is not

Answer 6

Degraded ecosystems

Answer 7

- Widespread perception that savannas are unnatural, arising from deforestation and fires lit by people - PROBLEM - large areas of savanna are targeted for restoration programmes for degraded land

Answer 8

- Many grass flora are adapted - Grazing- adapted species evolved in response to now-extinct megafauna - Grazing-adapted communities are today maintained by domestic cattle - We can work out fire adapted/ grazing adapted savannas based on characteristics of plants growing

Answer 9

Based on the characteristics of plants growing there

Answer 10

Fire and herbivory

Answer 11

Fire and herbivory

Answer 12

The tree must reach a set height to survive fires

Answer 13

Frequency of fires and rate of tree growth

Answer 14

Protection from herbivores If animals can reach growing tips they can stop tree growth

Answer 15

- Previous ecosystems characterised as forest can be defined as savannas based off the functional definition - Even savannas with high tree cover have dense ground cover and fire adapted trees - They all have a deep layer for continuous grasses and fire adapted trees

Answer 16

By fire-promoting grasses and fire-tolerant trees

Answer 17

- Forests maintained by shading which excludes shade intolerant grasses - Forests have no light for grass to establish so no fuel for fire

Answer 18

- Not climatically determined - Sharp boundaries between savanna and forest - Savannas are maintained by fire-promoting grasses and fire-tolerant trees - Forests maintained by shading which excludes shade intolerant grasses - Forests have no light for grass to establish so no fuel for fire - Forests and savannas coexist in the same climate, with abrupt transitions

Answer 19

- Long history of savanna use and management (old vegetation types) - When colonisers came and saw mosaics they presumed these were degraded ecosystems so planted trees - In reality this is misclassification and leads to miss management - Fire and grazing suppression in 'dry forests' - Leads to elimination of fire tolerant vegetation and forest establishment

Answer 20

- Fire and grazing suppression in 'dry forests' - Leads to elimination of fire tolerant vegetation and forest establishment

Answer 21

Savanna trees Tree growth and root storage depends on atmospheric CO2 Trees escape fire at high CO2, therefore reach escape height quicker, therefore reaching higher tree density

Answer 22

Rising CO2 promotes growth of savanna trees - Savanna trees are C3 - Grasses in savannas are C4 - Tree growth and root storage depends on atmospheric CO2, - Trees escape fire at high CO2, therefore reach escape height quicker, therefore reaching higher tree density - Rising CO2 benefits C3 trees more than C4 savanna grasses - Promotes growth of trees over grasses

Answer 23

Growth of trees over grasses

Answer 24

- Woody plant encroachment into savannas - Open savanna is covered in greater tree cover compared to less CO2 - Woody plants deplete savanna groundwater and threaten soil carbon stocks

Answer 25

- Less pasture for grazing domestic animals - Some charismatic animals require open landscapes - Firewood harvesting and charcoal production - Trees are often spiky and sharp, this is not good for cattle - Land cannot therefore be used for grazing

Answer 26

- Tropical forests are rich everywhere - Tree removal doesn’t suddenly result in rich ground flora - In an open savanna tree there is poor canopy diversity etc however ground flora is diverse - When savanna is encroached/ planted, diversity of ground layer is reduced and replaced with species poor trees etc - If tall trees grow or invade, this grassy layer is then competitively excluded to form a species poor canopy

Answer 27

- Fires and herbivores have ancient roles in maintaining savannas - Tree encroachment or planting in savannas degrades ecosystem functions and services - Colonial misclassification of these ecosystems led to mismanagement