Final

Question 1

Explain why crop genetic diversity in important and relevant in changing physical and biological environments.

Answer 1

Genetic diversity can be both good and bad.

Good: resistance to diseases, drought, etc.

Bad: ununiformity of production.

Diversity is especially important in breeding programs. In fields, however, we want less diversity and more uniformity.

Question 2

Define ecosystem service and disservice.

Answer 2

Functions of natural and managed ecosystems that enhance human well being.

Functions of natural and managed ecosystems that negative affect human well being.

Question 3

What are direct and indirect energy uses in respect to agricultural production. Examples?

Answer 3

Direct: on farm uses, such as fuels (equipment), natural gas, energy (pumping water, etc.).

Indirect: “embodied;” energy used off-farm in the production/transport of external inputs (fertilizers, pesticides, seeds, machinery, labor, etc.)

Question 4

What are the biggest energy uses in agricultural production? Which is direct/indirect?

Answer 4

(#1) Fertilizer/agrochemical production (indirect).

(#2) Fossil fuels for machinery (direct).

Food waste is another big indirect.

Question 5

Which is more energy-efficient, grain or vegetable production? What does the energy-centric perspective ignore about this?

Answer 5

Grain production, as per energy density compared to energy used in production.

It ignores nutrition value, and potential externalities up and downstream.

Question 6

How can grazing enhance rangeland productivity?

Answer 6

Optimal intensity/duration grazing stimulates roots and increases exudation, can suppress invasive species and free up space for other species, and livestock wastes prime decomposition pathways.

Question 7

What are ways that energy costs related to equipment use and fertilization can be reduced? What tradeoffs and other areas of management are involved?

Answer 7

Reduced tillage, reduce external inputs.

Electric equipment/tractors, optimize equipment efficiency, reduced passes through technology. Tradeoffs include costs of new equipment/maintenance etc.

Decrease equipment use. Tradeoff includes increases labor requirements for weeding etc.

Cover crops/compost to substitute for fertilizer inputs. Tradeoffs include seed/compost costs (cover crops more expensive than fertilizers, when including management), management considerations of cover crops, nutrient synchrony, etc.

Question 8

What is a portfolio effect in the context of biodiversity and ecosystem services? How does it relate
to resilience as discussed in the lecture on regenerative agriculture?

Answer 8

The stabilizing influence of biodiversity on ecosystem processes and services.

Greater biodiversity -> greater stability/resistance -> greater resilience

Question 9

How can we use traditional crop breeding to get genes into existing high quality rice strains while avoiding negative genetic impacts? What is the name of this process?

Answer 9

Artificial selection.

Question 10

Two main categories of methane reduction strategies.

Answer 10

Absolute reduction (feed additives, optimized feed, methane inhibitors, etc.) and product-based reduction (breeding for greater efficiency).

Question 11

What is upstream cost? What does including it to the energy ratio do? Why?

Answer 11

Refers to the raw materials required for production, including transportation, fertilizers, water, labor, etc.

Including it in the energy ratio lowers the efficiency (more input compared to less output).

Question 12

Explain how domestication, dispersal, and modern breeding have affected crop genetic diversity.

Answer 12

Reduced genetic diversity compared to wild progenitors.

Question 13

Why are crop wild relatives used in breeding programs? What are possible benefits and tradeoffs?

Answer 13

Important in breeding specific resistances (drought, disease, etc.). Adapted to different environments/stressors. Source of useful alleles for crop improvement.

Tradeoffs: difficult to cross different species, linked traits may be undesirable.

Question 14

What stages of the food system use the most energy?

Answer 14

Processing, transport, retail, packaging.

Question 15

Regenerative agriculture in its full definition moves through 5 levels. What are these?

Answer 15

Increase efficiency, substitute inputs, redesign the agroecosystem, re-establish food system connections, new global food systems.

Question 16

For a given crop, what quantities go into calculating its energy output?

Answer 16

Calories per unit yield. (per bushel, hectare, etc.)

MJ/ha/yr

Question 17

Define domestication in the context of agricultural crops. Identify traits that were commonly selected for during domestication (at least 6). Examples?

Answer 17

Selection to facilitate cultivation by humans and improve edibility/palatability.

1. Seed dispersal (indehiscence in beans/peas, loss of shattering in wheat)
2. No toxicity, bitterness, off flavors (cucumber, brassicas)
3. Growth habit/branching (tomatoes, corn)
4. Gigantism (grain size in rice, wheat, maize, barley; fruit size in tomato; flower size in sunflower)
5. Shape/color (brassicas)
6. Seedling vigor (???)

Question 18

What stages of the food system create the most GHG emissions?

Answer 18

Land use change, on-farm, and animal feed production.

Question 19

Negative impacts of overgrazing.

Answer 19

Loss of biodiversity, reduced water infiltration, topsoil erosion, compaction, waterway pollution, flooding.

Question 20

Tools to manage proper grazing.

Answer 20

Match number of animals to available forage, residual dry matter management, availability of water for animals (manages where animals go).

Also types of animals.

Question 21

Dietary gaps in world food/nutrition. How do they fit into importance of animals and animal products in different regions of the world?

Answer 21

Some regions have lower access to certain types of food that provide important nutrients and/or adequate caloric intake. Animal products can fill in important nutrient/calorie gaps in these regions, especially the global south.

Question 22

Define response diversity and provide an example of it. Explain how redundancy is an important
part of response diversity.

Answer 22

Refers to the variety of responses that different species or functional groups exhibit to environmental changes or disturbances. This diversity allows ecosystems to maintain their functions and services even when some species are lost or impaired.

Question 23

What is a landrace? Where in the historical timeline of domestication up through modern crop varieties do landraces fit in?

Answer 23

Landraces come after domestication. Initial dispersion from center of origin, recombination and adaptation to local environments.

Question 24

The main cause of high GHG emissions from ruminants in low income countries. How can it be mitigated?

Answer 24

Poor diet of animals. Increasing diet quality can reduce GHG emissions.

Question 25

Plant residue left at the end of the growing season (not eaten by livestock).

Answer 25

Residual dry matter.

Question 26

Which of the following characterize the type of diversity seen in crop rotation (planned, associated,
temporal, spatial). What are two separate ways this diversification promotes ecosystem service
(what is [are] the services it promotes)?

Answer 26

Planned and temporal (sometimes spatial if intercropping).

???

Question 27

Why is CA’s approach to mitigating GHG emissions from ruminants different than in low income countries?

Answer 27

Capital is available to invest in livestock efficiency. Reducing per capita GHG production. Breeding, high quality feeds, rumen modifiers, etc.

Question 28

Negative impacts of undergrazing.

Answer 28

Loss of biodiversity, invasive species takeover, increase fire load, lower productivity.

Question 29

Provide an example with associated biodiversity from lecture that illustrates complementarity and the sampling effect.

Answer 29

Complementarity: pollinators

Sampling effect: ???

Question 30

Where does promoting biodiversity at different scales fit into the framework of the five levels of regenerative agriculture?

Question 31

Residual dry matter.

Answer 31

Plant residue left at the end of the growing season (not eaten by livestock).

Question 32

For each of the traits commonly selected for during domestication, identify an advantage from a human perspective and a disadvantage from a plant’s perspective.

Answer 32

Reduced seed dispersal: easier to collect seeds; worse dispersal under wild conditions.

Reduced bitterness: better palatability; less pest defense.

Altered growth habit: better harvestable product; less total seed produced, worse photosynthetic potential.

Gigantism: better harvestable product; suboptimal resource allocation.

Shape/color: Desirable; suboptimal resource allocation.

Question 33

The relationship between biological diversity and ecosystem function is generally positive. What
are two mechanisms for why a single function (like NPP, pest management or pollination) would
increase with the diversity of organisms contributing to it?

Answer 33

Complementarity and the sampling effect (more likely to have high performing species)

Question 34

What is another challenge with GHG emissions in livestock production in CA (other than direct emissions from the animal). How is CA addressing it?

Answer 34

Animal wastes, manure. CA is moving away from lagoon management, towards biogas production etc.

Question 35

What is an energy efficiency ratio?

Answer 35

Energy output: energy input.

Question 36

How is lifecycle analysis used?

Answer 36

An analysis used to evaluate the environmental impact of a crop or livestock.

Question 37

Why did the formation of landraces lead to a genetic bottleneck? Why did an increase in diversity follow that bottleneck?

Answer 37

Desirable lines of existing landraces were preferentially dispersed resulting in new landraces with less diversity than the original (founder effects). ?????

Question 38

What is planned versus associated biodiversity with respect to agriculture? Explain how planned
biodiversity can also increase associated biodiversity?

Answer 38

Diversity in cropping elements vs. non-cropping elements.

Increasing planned biodiversity provides diverse resources for associated diversity to take hold.