are selectively logged forests worth protecting? (lecture 11)

Question 1

What is the extent of logging in tropical forests?

Answer 1

Asnet et al., 2009

• 2000-2005
• 20% tropical forests logged

Blaser et al., 2011
- 400 million hectares in permanent timber estate

• logged forests now dominate remaining tropical forest cover

Question 2

What is tropical logging?

Answer 2

• in temperate zone you get “clear cutting”
• in tropics: selective logging
• only large, marketable trees removed
• smaller or less desirable species left
• extent of damage depends on how much wood is cut

Question 3

How do selective logging management plans run? What does early re-entry logging do?

Answer 3

• cut trees above a certain DBH: 50-60cm
• harvest in rotations, ~40-70yrs apart
• early re-entry logging starting in some areas
• fish down the value chain
• reduced tree size ~40cm DBH
• reopen/create more logging roads
• further damages forest
• reduces future timber yields

Question 4

What is ecosystem functioning?

Answer 4

• biological, geochemical and physical processed that operate within an ecosystem, sustaining it and enabling it to supply ecosystem services
• nutrient cycling, seed dispersal, pollination etc
• interactions within/between ecosystem structural components
• biodiversity, water, soil etc

Question 5

What is the effect of logging on biodiversity?

Answer 5

negative

• logging changes species composition
• some species extinct in landscape
• logging harmful, relogging magnifies harm

positive

• substantial biodiversity persists
• including IUCN red-list specie e.g orang-utan
• less harmful than any other disturbance types (Gibson et al., 2011)

Question 6

What is the effect of conversion of tropical forest to agriculture on biodiversity?

Answer 6

• massive loss of biodiversity in oil palm converted land even compared to logged
• all species, espescially red list species

Question 7

What are the impacts of logging on species interactions?

Answer 7

• want to conserve whole network of life
• including species functioning
• functional diversity relates directly to ecosystem functioning
• involves array of traits e.g. feeding guilds, foraging behaviour, morphology
• shift of traits in logged forest
• ## big trait losses, small trait gainsoill palm
• birds: increase in granivorous, arrival of water related species, loss of bark gleaners
• dung beetles: absence of rollers, fewer diet generalists, more small bodied

Question 8

What are impacts on trophic (feeding) ecology?

Answer 8

• nitrogen isotopes of bird claw
• assimilate bird diet over 2-3 months
• determine how high individuals feed up the food chain
• measured trophic positions >1150 individuals of 73 species
• birds now feed higher up food chain

Question 9

What are impacts of logging on functioning?

Answer 9

• logged forest retains high diversity of functional traits (oil palm leads to dramatic loss)
• functional overlap in logged forest indicates resilience to further disturbance
• same species eat more insects than fruit in logged forest
• is this a sign of bad things to come, or sign that food web plasticity adds to community resilience against disturbance

Question 10

What are the impacts of logging on ecosystem services?

Answer 10

• tropical forests provide many ecosystem services
  e. g. carbon storage
• logging decreases C storage
• 47-97% range in C retained year after logging, variation in logging intensity
• average of 76%

Question 11

Are logged forests more vulnerable than primary forest?

Answer 11

• indonesian borneo
• rate of clearance same in logged forest/PAs
• active logging concessions protect forest
• clearance much higher in agriculture reclassifications from logging concessions
• revenue loss after logging make clearance attractive
• amazon
• rate of clearance of logging concessions same as primary forest <5 km and >25 km from roads
• 5-25 km from roads, logged forests 2-4 x more likely to be cleared

Question 12

How do roads for logging affect biodiversity?

Answer 12

• logging roads expanding
• 51,916km of logging road
• increasing 660km/yr since 2000
• increases accessibility & therefore bushmeat and roadkill
• elephant populations in african forest highest further from roads

Question 13

How does logging affect fires?

Answer 13

• canopy disruption and roads promote dessication
• fine slash from logging highly flammable
• susceptibility does diminish in a few years though

Question 14

Are logged forest worth protecting?

Answer 14

• vast in area
• logging is harmful to biodiversity
• but logged forests retain much biodiversity and carbon storage
• conversion of logged forests to agriculture causes bigger losses of both
• logging concessions need better management