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Trinity Term 1 > Agroecology: growing food sustainably > Flashcards

Agroecology: growing food sustainably Flashcards

1
Q

Agriculture covers … of the ice-free terrestrial earth surface

A

35-40%

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2
Q

… of agriculture is cropland

A

15,000,000 km2 (14%)

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3
Q

Describe cropland

A

‘arable’ + ‘permanent crops’

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4
Q

… of agriculture is pastures

A

30,000,000 km2

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5
Q

Most of the cultivatable land is…

A

already exploited

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6
Q

… of the planet’s terrestrial net primary productivity is appropriated by humans

A

~30%

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7
Q

What is agroecology?

A
  • application of ecological understanding and principles to agriculture
  • study of ecological processes that operate in agricultural production systems
  • can be applied to a variety of farming models
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8
Q

List some farming models

A

– organic
- conventional
- intensive
- extensive
- arable
- pastoral

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9
Q

What is the importance of agroecology?

A
  • make yields more sustainable
  • reduce impact of agriculture on biodiversity outcomes
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10
Q

What links yields and biodiversity

A

ecosystem service provision

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11
Q

Describe agricultural intensification

A

linked to the green revolution

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12
Q

Describe the green revolution

A

Increase production and productivity

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13
Q

Give some UK examples of agricultural intensification

A
  • land drainage
  • hedgerow removal
  • new crop types (e.g. oilseed rape)
  • ‘improvement’ of pasture
  • increased agrochemical inputs
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14
Q

Describe the policy underlying agricultural intensification

A
  • EU’s Common Agricultural Policy
  • subsidizes production and supports farmers’ income
  • costs ~€60bn/year (38% of the total EU budget), even though agriculture generates just 1.6% of EU GDP and employs only 5% of EU citizens
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15
Q

Describe some of the effects of agricultural intensification

A
  • fragmentation of natural and seminatural habitats
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16
Q

Describe fragmentation of natural and seminatural habitats

A
  • large populations with easy dispersal become small, fragmented extinction-prone populations
  • low connectivity inhibits recolonisation
  • induces range shifts in response to climate change
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17
Q

The food system is responsible for … of global greenhouse gas emissions

A

25 to 30%

18
Q

Give some examples of agricultural greenhouse gas emission

A
  • 5% from land conversion
  • CH4 from ruminants and irrigated rice
  • N2O from fertilisers
19
Q

Describe agriculture-dependent species

A
  • long history of agriculture
  • arable weeds
  • butterflies in early successional (grazed) habitats
20
Q

Describe the Adonis Blue butterfly (Polyommatus bellargus)

A

dependent on traditional grazing of chalk and limestone grasslands

21
Q

Describe the Shepherd’s Needle (Scandix pecten-veneris)

A
  • abundant until the 1950s
  • controlled as a weed
  • now conserved as a priority species through the UK Biodiversity Action Plan.
22
Q

Anthropogenic intensification reduces

A

the diversity of soil organisms

23
Q

Give some soil organisms that have been depleted due to anthropogenic intensification

A
  • nematodes in Cameroon
  • macrofauna in Peru
  • termites in West Africa
  • microbes in Wales
24
Q

Describe the general pattern for intensification on soil processes

A

alters the relative importance of bacterial versus fungal-based pathways of decomposition

25
Q

Describe the effect of intensive management (fertilizers, tillage) on soil

A
  • bacteria-dominated foodwebs
  • relatively inefficient nutrient use
  • more ‘leaky’ nutrient cycling
  • high carbon emissions
  • dependence on repeated inputs
26
Q

Describe the effect of low input management on soil

A
  • greater importance of fungi, earthworms and microarthropods
  • more similar to natural ecosystems
  • relatively efficient nutrient use
  • tighter recycling of nutrients
  • lower C emissions
  • less need for management inputs
27
Q

Describe the effect of intensification on pollination

A
  • erode above-ground ecosystem services
  • pollination increases with richness of wild bees and proximity to natural habitat
  • fruit set of open pollinated flowers is strongly positively correlated with bee species richness
  • number of social bee species is strongly negatively correlated with forest distance
28
Q

Describe organic farming

A
  • a form of agriculture that relies on ‘natural’ techniques
  • uses fertilisers and pesticides if they are considered ”natural”, but excludes or strictly limits the use of synthetic petrochemical fertilizers and pesticides
  • often regulated and legally enforced
  • 30% higher species richness than conventional farms
29
Q

Give some ‘natural’ agricultural techniques

A

– crop rotation
– green manure
– compost
– biological pest control

30
Q

Organic plots have…

A
  • more diverse microbial communities
  • correlated with more efficient functioning
31
Q

Describe earthworm biomass and abundance in organic plots

A

higher by a factor of 1.3 to 3.2

32
Q

Describe agroforestry

A
  • integration of existing or planted trees into crop farming systems
  • traditional part of many farming systems e.g. ‘home- gardens’
  • biodiversity benefits
33
Q

Describe the biodiversity benefits of agroforestry

A
  • (partial) replacement for forests – can support more than 2/3 of
    forest species
  • favourable matrix between forest remnants
  • livelihood benefits for local people
34
Q

Describe agri-environment schemes

A
  • farmers incentivized to farm in a wildlife-friendly way
  • entry level: ‘good agricultural and environmental condition’
  • higher level: more complex management; agreements are tailored to local circumstances
  • £400M/year to farmers in England
  • 60% of the land
35
Q

Give an example of an agri-environment scheme

A

Countryside Stewardship Schemes (Natural England)

36
Q

Describe the Environment Act 2021

A

Farmers and other land managers paid for delivering the following public goods:
* clean air
* clean and plentiful water
* thriving plants and wildlife
* protection from environmental hazards
* beauty, heritage and engagement with the environment
* reduction of and adaptation to climate change

37
Q

Describe land sparing

A

some land is farmed intensively to maximise yields while other land protected as a reserve

38
Q

Describe land sharing

A

All the land is farmed, but using wildlife-friendly techniques which may reduce yields

39
Q

Describe land sharing v land sparing

A
  • compared crop yields and densities of bird and tree species across gradients of agricultural intensity in southwest Ghana northern India
  • more species were ‘losers’ (negatively affected by agriculture) than ‘winners’ (benefiting from agriculture)
  • for most taxa in both countries, land sparing seems a more promising strategy
40
Q

Describe the problems with land sparing

A
  • lack the means to effectively protect areas in the long run
  • long record of sustainable land sharing
  • situations where both yields and biodiversity are high or where biodiversity depends on agriculture e.g. Mediterranean
  • vast regions with shallow soils or low rainfall are only suitable for non-intensive use
41
Q

Describe heterogeneity

A
  • loss of ecological heterogeneity is a universal consequence of agricultural intensification
  • the best predictor of biodiversity outcomes
  • future policy and management should aim to recreate
    heterogeneity as the best way of restoring and sustaining biodiversity in temperate agricultural systems.
42
Q

Agricultural diversification practices generally have a …

A

positive impact on biodiversity and ecosystem services, without compromising yield

Trinity Term 1 (38 decks)

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