Lecture 12 - managing farming to reduce biodiversity loss Flashcards
what is the biggest driver of the global extinction crisis
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
why is agriculture such a big problem?
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)
explain the issue of meat consumption
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
what is another use of agriculture other than direct food
increase in biofuel use - more US corn grown for biofuel than animal feed in 2010
what is the future of agriculture production
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
2 ways to manage agriculture expansion to minimise biodiversity loss
1) land sharing or land sparing farming
2) expand in low biodiversity areas
describe land sharing
- farm at lower intensity
- organic farming
- set-aside strips
- hedgerows
- woodlots/fragments
- biodiversity protected within agricultural matrix
describe land sparing
- farm at high intensity
- ‘industrial farming’
- use less land to meet demand
- biodiversity protected within remaining natural forest
how do you calculate which method of agriculture is best for a species
- 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
describe the oil palm experiment in Ghana looking at land sharing vs land sparing
- sampled birds and trees
- compare the abundance of each species under land-sparing and land-sharing
- divide them by winners and losers from farming
what are the results fo the Ghana experiment
- 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
what are source sink dynamics?
spillover of wildlife
describe an example where landscape configuration has an impact on which agricultural strategy is best
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
land sparing advantages
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
describe management of agriculture expansion by expanding in low biodiversity areas
- 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