Habitat Fragmentation

Question 1

How much of world’s forest 100m near an edge?

Answer 1

20% within 100m of an edge: especially proximally to agricultural, urban or other modified environments.

Question 2

How much world’s forest within 1km of a forest edge?

Answer 2

70%

Question 3

What are typical effects of fragmentation?

Answer 3

Edge effect, more susceptible to alteration of microclimates, human activity and non-native species.

Question 4

How do populations respond to fragmentation?

Answer 4

Decreased animal residency within fragments, reduced movement among fragments thus fragment recolonization after extinction.

Question 5

How are population dynamics impacted by fragmentation?

Answer 5

Release from predation and competition changed abundances, overall reduced.

Question 6

What is extinction debt?

Answer 6

Future extinction of species due to events in the past

Question 7

How may fragmentation affect species relative to their life-history traits?

Answer 7

Pioneer species favoured, leading to loss of large and old trees (thus impacting insects).

Question 8

What ecosystem services are impacted by fragmentation?

Answer 8

Reduced carbon and nitrogen retention, productivity and pollination.

Question 9

What are examples of function debt?

Answer 9

Delayed nutrient cycling and plant/consumer biomass changes.

Question 10

What may cause function debts?

Answer 10

Loss of biodiversity simplifies food webs, with nutrient loss and decomposition reduction.

Question 11

How can the Island Biogeography Model be used to describe fragmentation?

Answer 11

Islands representative, surrounded by a sea, as fragments unsuitable that may not be suitable for species.

Question 12

What are important questions regarding fragmentation?

Answer 12

How impacted by climate change, evolutionary responses of species and ecosystem services impact.

Question 13

How might fragmentation alter local biophysical condition variability?

Answer 13

Relatively unimportant drivers in intact systems may dominate, like increase wind shear, reduced fire frequency… Altered disturbance regimes.

Question 14

What are the forms of evolutionary adaptation to fragmentation?

Answer 14

This can occur on ecologically short time scales: local adaptations of phenotypic plasticity and evolutionary change.

Question 15

What models can be used to assess fragmentation?

Answer 15

Island biogeography models, however doesn’t account individual species, so metapopulation models

Question 16

What is edge contrast?

Answer 16

Similarity/dissimilarity between habitat and non-habitat areas and matrix quality in an absolute sense can affect both individual organisms and material fluxes.

Question 17

Why might habitat fragmentation impact BEF relationship through multiple pathways?

Answer 17

Fragmentations relationship with abiotic environment and biodiversity is established, but variable spatially and temporally.

Question 18

What are examples of fragmentatino impact on BEF relationship?

Answer 18

Non-random species loss of high ecosystem functioning species, and reduction of complementarity.

Question 19

Why might fragmentation impacts take long times to become apparent?

Answer 19

Affects long-term and scale dependent processes.

Question 20

What is the sampling effect?

Answer 20

This is the increasing chance of including a species of greater inherent productivity with increasing diversity.

Question 21

What is an example of non-random impact of fragmentation on BEF?

Answer 21

Large, old and later successional trees suffer more from edge effects due to canopy tree desiccation and promotes hyper abundance of alien pioneer species, pushing towards proliferation of fast growing and alien species.

Question 22

What is a consequence of large, older trees disproportionately suffering from the edge effect?

Answer 22

Large trees with higher wood density contribute most to aboveground biomass.

Question 23

How might this fragmentation lead to reduced complementarity?

Answer 23

Biotic homogenization with communities dominated by light-demanding and drought tolerant species, increased competition and decreased diversification.