Agricultural Intensification Flashcards
Food security
over the last 40 years major increase in production sees main grains produced 3x more in 50 years, and 4.5x more chicken, 2x more pigs
This is due to expansion of agricultural land and intensification of agriculture
Around 35% of global land is agricultural area
But hectares per capita is decreasing, yield increasing
5% increase per annum meat consumption in developing countries (livestock production causes 18% greenhouse gases)
2012 - 7 billion people; 2046 - 9 billion people
Prices for meat, cereal, and all foods
has increased dramatically over the last 20 years. Controversy with biofuels as it’s burning food
Food prices impacted by
Commodity trading
e.g. 2010 Russian wildfires & drought.
Yield reduced by <5%. Prices increased 50%
Increased oil prices
Climate trends were large enough in some countries to offset a significant portion of the increases in average yields that arose from technology, carbon dioxide fertilization, and other factors.
A third of food produced is wasted
But tackling waste not sufficient to meet demand
Developing countries 1/3 waste is on-farm, 1/3 through transport and processing Godfray et al. 2010 Science 327, 812-818
Developed countries 1/3 of waste is at home and municipal
AGRICULTURAL EXTENT
Globally humans acquire 30% of net primary productivity; 72% western Europe. Imhoff et al 2004 Nature 429, 870–873
Change in area of annual crops 1999-2008 increasing greatly in Africa and brazil and India
Land converted to crop and pasture has increased 50% in 300 years. Most of which are endemic bird areas
Pesticide and land use
are increasing a lot
AGRICULTURAL IMPACTS
20-25% of pre-agricultural bird numbers lost by 1990 Gaston et al 2003 Proc Roy Soc B 276, 1293-1300
Agriculture is the biggest threat to globally endangered bird species
Similar for other groups eg 80% of threatened vertebrates (amphibians and reptiles)
Increased yield and intensive productions lead to
decreased population in farmland birds
More plants become classified as rare or threatened
as yield increases and production is intensified
Intensification of agriculture and bees
Organic areas near to natural areas increase plant diversity but not when organic far from natural areas and not with conventional far from natural areas
Livestock and wild environments
livestock grazed lands have 10 times less total animal biomass than livestock-free lands, same for overall density
Cattle & zebra diets & habitat selection very similar Experiment Laikipia, Kenya (Young et al. 2005)
c. 10 cattle/km2 & 0 cattle/km2
excluding cattle increases zebra by 46%
Grass cover reduced by cattle & correlates +ve zebra Indirect facilitation - effects reduced by elephants
Wild game better adapted than livestock Fewer inputs & less habitat modification Britain: deer, rabbits etc.
BUT
Needs policy and legislative change
Setting quotas
Creates extra bushmeat demand? Enforcement
Strategy for policy change
Monitoring - Diagnosis - Design & test solutions - Deploy effective management - Monitor Outcome
Requires sound science, economic and environmental drivers, government, NGOs, Farmers and Industry, Effective technology transfer
Philpott et al 2008 Conservation Biology
Certification in coffee in costa rica
Cirl bunting distribution
Voluntary set-aside - RSPB stubble - Set-aside - Countryside stewardship special projects increased cirl population
Habitat requirements
• Weedycerealstubbles(winter)
• Mix of grassland (insects) & cereals (ripening grain) (summer)
• Winter & summer habitat close together
• Polarization of farmland & increased herbicide, insecticide and fertilizer use have all contributed to cirl decline
UK agri-environment schemes
Entry level stewardship: −Launched 2005 −Uptake relatively high −Clearly defined broad objectives −Evidence-based simple prescriptions
Higher level stewardship handbook -- Launched 2005 − Uptake lower − Clearly defined, narrow objectives −Evidence-based complex prescriptions − Geographical targeting − Project officers − Payments linked to delivery of habitat quality
Review of agri-environment schemes
5 European countries & 202 paired fields
Marginal to moderate benefits in all countries
Common species benefit more than rare ones Red data book species rarely benefit
More detailed tailoring of schemes required
RSPB Hope Farm Breeding Bird Index 2017
Skylark 10 to 35 pairs from 2000 to 2017 Grey partridge 0 to 7 pairs Starling 3 to 16 pairs
Linnet 6 to 22 pairs Yellowhammer 14 to 34 pairs
Average profit £60,000 per annum
Land sparing is best for most populations
aka by the highest permissible yield
But low intensity farming can be essential
30 globally endangered bird species rely on low intensity farming
Land-sparing core assumption
Intensification means inefficient farms are abandoned and rural to urban migration which lead to forest regeneration
Land-sparing model’s core assumption
Perfecto & Vandermeer 2010 PNAS 107, 5786-5791
El Salvador: local rural population density uncorrelated with forest recovery
Argentina: rural population declining, but forest cover also declining
Mexico: 16 of 17 studies conditions meet forest transition model, but still net deforestation
Costa Rica: intensification, rural to urban migration & ecotourism revenues, but forest fragmentation continues
SUMMARY
Much of the globe’s land is used for food production
Area of farmland and intensification will increase in the future
Agricultural expansion and intensification drive wildlife declines
But agri-environment schemes based on strong science can reduce the negative impact
Much debate regarding land-sharing vs sparing approaches
Reading list
Phalan et al 2011 Science 333, 1289-1291
Macedo et al 2012 PNAS 109, 1341-1346
Perfecto & Vandermeer 2010 PNAS 107, 5786-5791
