Lecture 14: Fragmentation

Question 1

forest clearance is rarely wholesale and after ______ are retained in the landscape

Answer 1

fragments of forests

Question 2

habitat fragmentation:

Answer 2

a large expansion of habitat is transformed into a number of smaller patches isolated from each other by a matrix of habits unlike the original

Question 3

3 stages to fragmentation procesS:

Answer 3

1) initial habitat loss
2) isolation of blocks of habitat
3) increased isolation due to further land-use changes

Question 4

deforestation is usually =

Answer 4

NON RANDOM

• -some habitats cleared preferentially
• –geog
• –physical accessibility

Question 5

some species are poorly represented or absent in fragments from

Answer 5

outset = sample effect

Question 6

ecological foundations to fragmentation research =

Answer 6

species-area relationships and island biogeography theory

Question 7

what do islands & mountain tops have in common?

Answer 7

they both demonstrate relationships between area of habitat and number of species that survive in that area

Question 8

species-area relationship curve=

Answer 8

S=cA^z 
species richness
area
c = species richness factor 
z = species accumulation factor

Question 9

the theory of island biogeography:

Answer 9

MacArthur & wilson 1967
oceanic islands were viewed as relatively static in species composition
-no. of species was a dynamic equilibrium between extinction and colonisation

Question 10

IBT: (island biogeograhoy theory)

Answer 10

• local extinction rate is a function of island size
• colonisation rate is a function of island isolation from the mainland
• -> if these r true, no. of species is largely determined by its size and isolation

Question 11

rapid loss of species with large area reuiqrements:

Answer 11

• predators
• large bodied species
• elevational migrants
• -and forest-interior specialists

Question 12

increasing distance from contiguous forest means than fragments are more

Answer 12

isolated

Question 13

what is the habitat matrix?

Answer 13

habitat that surrounds forest fragments and ‘connect;s them to other or closest forest

• can support populations of some species found in forest
• fragments conncectd for these species

Question 14

matrix not suitable for species

Answer 14

• colonisation rates decline

- useable habitat shrinks vice versa =if hospitable

Question 15

extinction debt =

Answer 15

long term issues, at first many species remain.

• • overtime many species go extinct
• -future ecological cost of current habitat destruction

Question 16

reduce extinction debt

Answer 16

-increase fragment size ( but lots of area required)

Question 17

edge effect =

Answer 17

disturbance that penetrates into a fragment

Question 18

abiotic edge effects =

Answer 18

light
temp
wind
humidity

Question 19

biotic edge effects

Answer 19

predation
soil
transpiration rate
species turnover

Question 20

edge effects can extend how far into forests

Answer 20

up to 400 m v far

Question 21

ecosystems function: effect of fragmentation, large predator lost=

Answer 21

increase in herbivores, increase in seed predators–> resulting in reduce number of saplings

• reduced seed dispersal
• reduced wood density

Question 22

what does fragmentation tell us about protected area management

Answer 22

-maintaining connectivity (IBT stresses importance) –> corridor

Question 23

value of corridors

Answer 23

• linear habitat remnant surrounded by the modified matrix, wildlife movement
• -wider and better quality corridors, but value degrades with distance

Question 24

fragment + corridors =

Answer 24

biodiversity

-wider & higher quality is better