EGS Pippin 5. Biome boundaries of SA

Question 1

Fynbos Boundaries P1/4

What factors determine Fynbos boundaries?

Answer 1

• Fynbos Reproductive Ecology
• Fire
• Rain
• Soil

Question 2

Fynbos Boundaries P2/4

Fynbos Reproductive Ecology:

• Flower (); mostly () in () to () in (), along the ().
• Mostly () pollinated; some (); less ().
• Most rely on () linked to (), some ().
• () seeds account for () soil → rapid (), allowing it quickly () after ().
• () → ants harvest () from seed and then () it, which () seeds from ().
• These factors give it a () over other species.

Answer 2

• Flower variably; mostly Spring in West to Summer in East, along the rainfall gradient.
• Mostly insect pollinated; some wind; less birds/animals
• Most rely on seed germination linked to fire, some resprout
• Protein rich seeds account for low nutrient soil → rapid root production, allowing it to quickly establish after fire.
• Myrmecochory → ants harvest eliasome from seed and then bury it, which protects seeds from predation.
• These factors give it a competitive advantage over other species

Question 3

Fynbos Boundaries P3/4

Fynbos vs Forest
* Main:

• Fynbos () suitable for trees
• () & () keep trees out
• Forests emerge in ()/() & are protected from () → once () can () and be more () resistant → create () that can ().
• Forests can also change the () & influence () → ().

Answer 3

• Main: Fire but also low nutrient soil.
• Fynbos climate suitable for trees
• Infertile soils & fire keep trees out
• Forests emerge in kloofs/valleys & are protected from fire → once established can encroach & be more fire resistant → create forest patches that can retard fire
• Forests can also change micro-biome & influence surrounding areas → biome shift.

Question 4

Fynbos Boundaries P4/4

Fynbos vs Succulent Karoo

• Main:
• Karoo () replaces Fynbos when () is () on more () & () soils
• Karoo () tend to () when () is () due to low water availability bc. () tend to become () to ().
• Boundary btwn them is considered () & ().
• Another view: the boundary is determined by (), i.e. the () of () versus () & () bc. being () is () in terms of () & () versus () & (), which have a () in () environments.

Answer 4

• Main: Rain & Fire secondary
• Karoo shrubland replaces Fynbos when rain is less than 200-300 mm pa on more nutrient-rich & less acidic soils.
• Boundary btwn. them is considered patchy & dynamic.
• Another view: the boundary is determined by climate, i.e. the cost of evergreeness versus drought deciduousness & succulence, which have a competitive advantage in drier environments.

Question 5

Succulent Karoo Boundaries P1/3

What factors determine Succulent Karoo boundaries?

Answer 5

• Duration of Growing Season
• Temperature
• Rain
• Succulent Karoo Reproductive Ecology

Question 6

Succulent Karoo Boundaries P2/3

Duration of Growing Season & Temperature:

• Enjoys a () & () growing season, with () but very (), () rainfall.
• vs Nama Karoo growing season =
• vs Savanna growing season =
• vs Desert growing season =
• vs Fynbos growing season =

Answer 6

• Enjoys a short & cool growing season, with low but very predictable, winter rainfall.
• vs Nama Karoo growing season = short & warm
• vs Savanna growing season = long & warm
• vs Desert growing season = lower & less reliable rainfall
• vs Fynbos growing season = more rainfall & cooler summers

Question 7

Succulent Karoo Boundaries P3/3

Succulent Karoo Reproductive Ecology:

• Plants tied to (); () → () quickly to ().
• () pollination critical; high () diversity; low () pollination
• () → () demand on () at one time.
• Seeds () dispersed; mechanisms () dispersal until ().

Answer 7

• Plants tied to seasonal rainfall; Short roots → respond quickly to surface rain water
• Insect pollination critical; high insect diversity; low self-pollination
• Sequential flowering → limits demand on pollinators at one time
• Seeds wind/water dispersed; mechanisms delay dispersal until favourable.

Question 8

Forest Boundaries P1/2

What factors determine forest boundaries?

Answer 8

• Rain
• Fire

Question 9

Forest Boundaries P2/2

• (), meaning they have () boundaries
• Can () in other biomes
• Boundary is determined on (), () () & lack of ().
• Forest vs Fynbos, determing factor =
• Forest vs Grassland, determing factor =

Answer 9

• Atonal, meaning they have hard to define boundaries.
• Can pop up in other biomes
• Boundary is determined on high volume, non-seasonal rainfall & lack of fire.
• Forest vs Fynbos, determing factor = lack of fire -> encroachment
• Forest vs Grassland, determing factor = lack of fire -> encroachment

Question 10

Savanna Boundaries P1/4

What factors determine Savanna boundaries?

Answer 10

• Summer rainfall
• Warm, dry winters
• Herbivory
• Fire
• Frost (temp.)
• Moisture
• Human activity

Question 11

Savanna Boundaries P2/4

Savanna vs Grassland:

• () boundary associated w. (), where during (), Grasslands experience ().
• () decrease w. an increase in () -> too () for () & thus a () marks the boundary btwn. them.

Answer 11

Savanna vs Grassland:
* SE boundary associated w. dry season temps, where during winter, Grasslands experience frost
* Temps. decrease w. an increase in altitude -> too cold for trees & thus a temperature gradient marks the boundary btwn. them.

Question 12

Savanna Boundaries P3/4

Savanna vs Nama Karoo:

• Savannas () into () of Nama Karoo in the () & () & ().
• As () decreases, () tend to () of the landscape, and become () only to (), thus there is a ().

Answer 12

• Savannas grade continously into arid shrubland of Nama Karoo in the Eastern & Northern Cape & Namibia.
• As water availability decreases, trees tend to drop out of the landscape, and become confined only to drainage lines, thus there is a moisture gradient/boundary.

Question 13

Savanna Boundaries P4/4

Savanna vs Forest:

• To the () of the Savanna biome, () savannas () into () & open () forest.
• Where savannas border () onto (), savannas usually () & () through () means.
• Pockets of forests in savannas occur in areas of () or ().

Answer 13

• To the north of the Savanna biome, moist savannas grade into woodland & open semi-deciduous forest.
• Where savannas border directly onto Evergreen Tropical Forest, savannas usually secondary & maintained through human means.
• Pockets of forests in savannas occur in areas of higher rainfall or moisture.

Question 14

Grassland Boundaries P1/2

What factors determine grassland boundaries?

Answer 14

A subtle interplay between climate, topography (altitude), fire and grazing

Question 15

Grassland Boundaries P2/2

• () balance of () & () = () grasses
• Why No Trees?
  • () → ()
  • soil too (), ()
  • poor () → grassland either too () or too ()
  • () at ()
  • ()

Answer 15

• Fine balance of moisture content & temp. = happy grasses.
• Why No Trees?
  • anthropogenic artifact → false
  • soil too shallow, impervious
  • poor drainage → grassland either too water logged or too dry
  • Frost at high altitudes
  • Fire

Question 16

Nama Karoo Boundaries P1/2

What factors determine Nama Karoo boundaries?

Answer 16

• Low rainfall
• Rainfall uncertainty
• Soils (to a lesser extent)
• Role of land management & grazing debated

Question 17

Nama Karoo boundaries P2/2

Nama Karoo Hypothesis:

• Proposed by:
• Idea:
• () through () was causing the Nama Karoo to move () & (), with encroaching () from the ().
• Argument on the basis that () induced () drive () that confuse the () of (), () them.
• In the case of Nama Karoo & () shifts, () or () () can () the proportions of () & () and () ()
• However, the hypothesis remains ().

Answer 17

• Proposed by: John Acocks
• Idea: Nama Karoo was encroaching on Grassland
• Degradation through over grazing was causing the Nama Karoo to move north & east, with encroaching desert from the north.
• Argument on the basis that management induced changes drive shifts that confuse the seperation of boundaries, blurring them.
• In the case of Nama Karoo & Grassland shifts, heavy or sustained grazing can increase the proportions of succulents & shrubs and reduce grassiness.
• However, the hypothesis remains unproven

Question 18

Desert Boundaries P1/3

What factors determine Desert boundaries?

Answer 18

2 Gradients:
* North-South that runs from tropical to temperate

• Coastal-Inland on an East-West axis.

Question 19

Desert Boundaries P2/3

North-South Tropical to Temperate gradient:
* Bounded @ the () extreme by the () () which is the () end of this gradient, w. () temps & () relative humidity & associated () ().

• @ () extreme, the biome () into () () conditions, w. () potential ().

Answer 19

• Bounded @ the southern extreme by the winter rainfall Succulent Karoo, which is the wetter end of this gradient, w. mild temps & higher relative humidiity & associated low evapotranspiration.
• @ northern extreme, the biome grades into summer tropical rainfall conditions, w. high potential evapotranspiration.

Question 20

Desert Boundaries P3/3

Coastal-Inland East-West gradient:

• () of the 2 gradients.
• The () present () temps & () humidity w. (), while () has much () temps & () humidity.
• The 2 gradients ().

Answer 20

• Steeper of the 2 gradients.
• The Coast presents milder temps & higher humidity w. fog, while Inland has much hotter temps & low humidity.
• The 2 gradients amplify each other.