Agroecology: growing food sustainably

Question 1

Agriculture covers … of the ice-free terrestrial earth surface

Answer 1

35-40%

Question 2

… of agriculture is cropland

Answer 2

15,000,000 km2 (14%)

Question 3

Describe cropland

Answer 3

‘arable’ + ‘permanent crops’

Question 4

… of agriculture is pastures

Answer 4

30,000,000 km2

Question 5

Most of the cultivatable land is…

Answer 5

already exploited

Question 6

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

Answer 6

~30%

Question 7

What is agroecology?

Answer 7

• 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

Question 8

List some farming models

Answer 8

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

Question 9

What is the importance of agroecology?

Answer 9

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

Question 10

What links yields and biodiversity

Answer 10

ecosystem service provision

Question 11

Describe agricultural intensification

Answer 11

linked to the green revolution

Question 12

Describe the green revolution

Answer 12

Increase production and productivity

Question 13

Give some UK examples of agricultural intensification

Answer 13

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

Question 14

Describe the policy underlying agricultural intensification

Answer 14

• 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

Question 15

Describe some of the effects of agricultural intensification

Answer 15

• fragmentation of natural and seminatural habitats

Question 16

Describe fragmentation of natural and seminatural habitats

Answer 16

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

Question 17

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

Answer 17

25 to 30%

Question 18

Give some examples of agricultural greenhouse gas emission

Answer 18

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

Question 19

Describe agriculture-dependent species

Answer 19

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

Question 20

Describe the Adonis Blue butterfly (Polyommatus bellargus)

Answer 20

dependent on traditional grazing of chalk and limestone grasslands

Question 21

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

Answer 21

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

Question 22

Anthropogenic intensification reduces

Answer 22

the diversity of soil organisms

Question 23

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

Answer 23

• nematodes in Cameroon
• macrofauna in Peru
• termites in West Africa
• microbes in Wales

Question 24

Describe the general pattern for intensification on soil processes

Answer 24

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

Question 25

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

Answer 25

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

Question 26

Describe the effect of low input management on soil

Answer 26

- 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

Question 27

Describe the effect of intensification on pollination

Answer 27

- 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

Question 28

Describe organic farming

Answer 28

- 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

Question 29

Give some 'natural' agricultural techniques

Answer 29

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

Question 30

Organic plots have...

Answer 30

- more diverse microbial communities - correlated with more efficient functioning

Question 31

Describe earthworm biomass and abundance in organic plots

Answer 31

higher by a factor of 1.3 to 3.2

Question 32

Describe agroforestry

Answer 32

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

Question 33

Describe the biodiversity benefits of agroforestry

Answer 33

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

Question 34

Describe agri-environment schemes

Answer 34

- 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

Question 35

Give an example of an agri-environment scheme

Answer 35

Countryside Stewardship Schemes (Natural England)

Question 36

Describe the Environment Act 2021

Answer 36

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

Question 37

Describe land sparing

Answer 37

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

Question 38

Describe land sharing

Answer 38

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

Question 39

Describe land sharing v land sparing

Answer 39

- 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

Question 40

Describe the problems with land sparing

Answer 40

- 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

Question 41

Describe heterogeneity

Answer 41

- 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.

Question 42

Agricultural diversification practices generally have a ...

Answer 42

positive impact on biodiversity and ecosystem services, without compromising yield