Lecture 11 - Selective logging

Question 1

describe the prevalence of logging

Answer 1

• between 2000-2005, 20% of tropical forests were logged
• over 400 million hectares of tropical forest in permanent timber estate
• logged forests now dominate remaining tropical forest cover
• 22% of animals in tropical forests live in protected areas and 42% live in active or former logging concessions

Question 2

describe the difference between temperate and tropical logging

Answer 2

• in temperate zones = clear cutting
• in the tropics = selective logging = only large marketable trees removed - smaller or less desirable species left
• damaged forest remains
• damage depends on how much wood cut

Question 3

what are the impacts of selective logging

Answer 3

• reduced tree size
• creating more logging roads
• further damaged forest and reduced future timber yields

Question 4

what are concessions management plans?

Answer 4

• only cut trees above set DBH (50-60cm)
• harvest in rotations, typically 40-70yrs apart
  (re entry logging is starting in some areas)

Question 5

what is ecosystem functioning?

Answer 5

‘the biological, geochemical and physical processes that operate within an ecosystem, sustaining it and enabling it to supply ecosystem services’

Question 6

examples of ecosystem functions

Answer 6

structural components: nutrient cycling, seed dispersal, pollination
interactions within and between the structural components of ecosystems: biodiversity, soil, water etc

Question 7

3 effects of logging on biodiverstiy

Answer 7

1) species composition
2) ICUN red-listed bird species
3) % of unlogged species persisting

Question 8

how would you study birds, dung beetles and lead-litter ants

Answer 8

birds - point counts and understorey birds with mist nets
dung beetles - baited pitfall traps
leaf-litter ants - winkler traps

Question 9

when studying taxa what would you observe

Answer 9

study their key functional roles e.g. seed dispersal, nutrient recycling and predation

Question 10

what have studies shown to be the effects of logging on biodiversity

Answer 10

• species composition differs
• red-listed birds have significantly decline in once logged and twice logged forests
• most primary forest species persist

Question 11

what are the negatives of logging

Answer 11

• changes species composition
• some species apparently extinct in landscape
• logging is harmful, re-logging magnifies ham

Question 12

positives of logging

Answer 12

• substantial amount of biodiversity persists

- includes red listed species e.g. orang-utans (primary forest species)

Question 13

what is the biggest threat to logged forests

Answer 13

conversion to agriculture which causes a massive loss of biodiversity

Question 14

what is functional diversity?

Answer 14

• incorporates array of functional traits
  e. g. feeding guilds, behavioural forging strategies, morphological adaptations
• yields a single continuous measure
• directly relates to ecosystem functioning

Question 15

what is functional richness?

Answer 15

the maximum amount of function trait spread - so the greater the number of functional trait combinations the greater the volume fo functional space
- experiment showed this to be dramatically different between primary forest and oil palm for both birds and dung beetles

Question 16

describe functional diversity after agricultural conversion

Answer 16

• FD is similar in logged forest to primary but declines after conversion

Question 17

what can be a positive of twice logged forests

Answer 17

disturbance tolerant species in twice logged forest introduces additional functional traits

Question 18

describe how the balance of functional traits can alter as the community composition changes

Answer 18

• in some cases there is a direct replacement of one species for another
• in other cases there is a complete absence or addition of a particular trait
• some traits become more or less common

Question 19

give an example of shifts of functional traits

Answer 19

• in oil palm granivorous bird species increased in abundance
• addition of water related species which don’t occur in forest
• loss of bark gleaning species (e.g. woodpeckers)
• dung beetles were also absent in oil palm when they are highly abundant in forest
• the most abundant species were also smaller
• decline in number of diet generalist species

Question 20

how can they look at the impact of logging on trophic (feeding) ecology?

Answer 20

• experiment looking at the Nitrogen isotopes of bird claws - assimilate bird diet over 2-3 months - determine how high individuals feed up the food chain
• results show birds in degraded forest feed higher up the food chain

Question 21

what are the impacts of logging on functioning?

Answer 21

• logged forest retains high diversity of functional traits whereas oil palm results in a loss
• functional overlap in logged forest- resilience to further disturbance
• same species eat more insects than fruit in logged forest
• food web plasticity endows communities with resiliance to disturbance

Question 22

what are ecosystem services?

Answer 22

provides human society with many ‘services’

e. g. primary forests store billions tons of carbon - carbon sinks for 3+ decades, absorbing more carbon than they emit
- mitigates climate change

Question 23

what are the impacts of logging on ecosystem services?

Answer 23

• carbon storage declines after logging but an average of 76% of carbon is retained one year post logging
• 47%-97% range, reflecting variation in logging intensity

Question 24

3 points summarising effects of selective logging

Answer 24

1) logging is harmful to biodiversity but they do retain much biodiversity value
2) there are hidden impacts on functional ecology
3) logged forests store and absorb much carbon

Question 25

3 challenged for logged forests?

Answer 25

1) promotes clearance
2) roads and bushmeat hunting
- 38% of all roads are logging roads
- animals walk on roads = bushmeat
3) fires
- canopy disruption and roads promote desiccation
- fire stash from logging = highly flammable
- fortunately susceptibility to fire diminishes within a few years

Question 26

is logged forest more vulnerable than primary forest?

Answer 26

• in borneo that rate of clearance of logging concessions is same as protected areas
• active logging concessions protect forest
• when logging concessions reclassified for agriculture, clearance is much higher
• loss of revenues are logging makes clearance attractive

Question 27

rate of clearing in the Amazon

Answer 27

• rate of clearing of logging concessions is same as primary forest <5km and >25km from road but between 5-25km logged forests are 2-4 times more likely to be cleared - however it is unclear wether this is planned conversion

Question 28

future of logging

Answer 28

logged forests are worth protecting to prevent conversion into agriculture - need to better manage concessions