Lecture 12 - managing farming to reduce biodiversity loss

Question 1

what is the biggest driver of the global extinction crisis

Answer 1

extreme global expansion of tropical agriculture - primarily at the expense tropical rainforest (global imbalance in deforestation)

• resulting in massive loss of biodiversity
• 1980-2012 = 154 Mha converted

Question 2

why is agriculture such a big problem?

Answer 2

agricultural systems are vastly simplified compared to rainforests
- forest conversion is set to continue due to rapidly expanding population, more people =more mouths to feed (1.5 billion overweight/obese people)

Question 3

explain the issue of meat consumption

Answer 3

there is currently more meat consumption per capita but you can get 18x more protein Ha-1 from soy than beef - beef is less sustainable

Question 4

what is another use of agriculture other than direct food

Answer 4

increase in biofuel use - more US corn grown for biofuel than animal feed in 2010

Question 5

what is the future of agriculture production

Answer 5

in the next 40 years, agricultural production could grow by 60-100%

• may need to double farm output by 2050
• future of global biodiversity in hands of agricultural policy makers

Question 6

2 ways to manage agriculture expansion to minimise biodiversity loss

Answer 6

1) land sharing or land sparing farming

2) expand in low biodiversity areas

Question 7

describe land sharing

Answer 7

• farm at lower intensity
• organic farming
• set-aside strips
• hedgerows
• woodlots/fragments
• biodiversity protected within agricultural matrix

Question 8

describe land sparing

Answer 8

• farm at high intensity
• ‘industrial farming’
• use less land to meet demand
• biodiversity protected within remaining natural forest

Question 9

how do you calculate which method of agriculture is best for a species

Answer 9

• calculate the total abundance of each species across landscapes
• plot a density-yield curve
• shape of curve determines if land-sharing or land-sparing is best for a species
• land sharing best = concave curve
• land-sparing best = convex curve

Question 10

describe the oil palm experiment in Ghana looking at land sharing vs land sparing

Answer 10

• sampled birds and trees
• compare the abundance of each species under land-sparing and land-sharing
• divide them by winners and losers from farming

Question 11

what are the results fo the Ghana experiment

Answer 11

• in oil palm - land sparing is best - especially for species with small ranges
• potential role of surrounding landscapes - species could disperse into test landscapes from forest elsewhere - species could use resources from outside landscape

Question 12

what are source sink dynamics?

Answer 12

spillover of wildlife

Question 13

describe an example where landscape configuration has an impact on which agricultural strategy is best

Answer 13

cattle farming in the Andes - sample birds in cattle pastures and forest

• sample at a range of distances from contiguous forest
• total species richness decreases with distance from forest for land sharing but stays relatively constant for land sparing

Question 14

land sparing advantages

Answer 14

land sparing - best for biodiversity

• need adequate safeguards
• more species have higher abundance
• higher landscape-level species richness
• increasingly better further from contiguous forest edge
• best for carbon storage
• need to intensify existing tropical farmland

Question 15

describe management of agriculture expansion by expanding in low biodiversity areas

Answer 15

• using areas which have already been degraded across the tropics e.g. burned multiple times, erosion, converted farmland, imperata grasslands in SE Asia
• can meet 2020 oil palm demand without forest loss if we focus on degraded lands

Question 16

what two habitats dominate in the Llanos?

Answer 16

1) Anthropogenic/semi-natural grassland

2) natural forest patches

Question 17

describe the experiment investigating into development of oil palm at minimal cost to either habitat (anthropogenic/ semi natural grassland and natural forest patches)

Answer 17

• study taxa - ants, dung beetles, birds, herpetofauna
• study area
• look at 3 effects of oil palm on biodiversity
  1) species richness - differs
  2) species composition - differs
  3) occurence of forest species in oil palm and pasture - declines

Question 18

summary of llanos experiment?

Answer 18

• forest patches have most species
• oil palm more species rich than pasture
• forest species have higher occurence in oil palm than in pasture
• minimal biodiversity impacts of converting llanos pasture to oil palm but is vital to preserve forest patches

Question 19

describe sustainability labelling

Answer 19

• technique to persuade oil palm industry to develop in such areas
• media and consumer pressure
• advertising products that come from sustainable oil palm agriculture
• 400 global retailers cut al deforestation from supply chains by 2020
• deforestation free palm oil increases cost of production by what translates into mars bar price increase of 0.0001p

Question 20

what is the issue with expanding in low biodiversity areas

Answer 20

not enough forest free areas to meet demand beyond 2025

Question 21

what is a possible solution to meet high oil palm demand?

Answer 21

• higher yielding varieties - produce more crop per ha on existing land
• genome sequencing for producing pest and drought resistance - big forest saving potential

Question 22

what is the danger of yield increases?

Answer 22

• markets are globally interconnected, buyers can substitute one crop for another - transfer from temperate to tropics
• governments must zone areas for high-yielding crops coupled with forest estates
• without this safeguard land sparing could be in the temperate zone