Ben-Gurion University of the Negev · Ben-Gurion University of the Negev Prof. Bertrand Boeken The Wyler Dept. of Dryland Agriculture Jacob Blaustein Institute for Desert Research
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Agroecology Ecological understanding of farming systems
Ben-Gurion University of the Negev
Prof. Bertrand Boeken The Wyler Dept. of Dryland Agriculture Jacob Blaustein Institute for Desert Research Ben-Gurion University of the Negev Sede Boqer Campus 84990 Israel Office 08-659 6893 Mobile 052-3847603
• Fertilizer application • Pest control • Harvesting
11
Historical perspectives
Increasing trends • Global and local human population size • Control over food production
• Dependence on technology, transport
Time-line (yrs) Archaic Homo sapiens -250,000 hunting-gathering, nomadic
Prehistoric -15,000 domesticated plants and grazers
Ancient -5,000 soil cultivation, irrigation
Medieval -1,500 deep plowing, manure, selection, profit
Modern -200 scientific approach
Contemporary -60 industrialization, alternative approaches, ecological sustainability (?)
12
Early human foraging
250,000 years ago • Nomadic hunter-gatherers
• Small communities in open landscapes
• Human evolution and early cultural development
http://www.archaeologyinfo.com/homosapiens.htm
Social structure: clan/family groups Food: grains, nuts, berries, tubers, vertebrates, insects Problems: predators, resource depletion, adverse selection, rival clans Innovations: clothing, domestication of dogs
13
Adverse selection Gathering of wild cereal grain
• Normal retention frequency distribution
• People collect seeds remaining on the plants • Moves population mean to genotypes with
lower retention
• In short time local populations become costlier to collect
Seed retention
Freq
uenc
y
Seed retention
Freq
uenc
y
Harvested
www.flickr.com
Assumptions • Essential or important food source • Abundant population • No overharvesting by reducing
abundance (no seed limitation of recruitment)
Consequences (Based on optimal foraging decisions by humans) • Diversity of food sources (“prey switching”) • Migration (nomadism)
14
Prehistoric agriculture
www.sanford-artedventures.com
Social structure: larger clan/family groups Food: wild animals and plants, local produce Problems: predators, resource depletion, rival clans Innovations: tools, domestication of grains, herbivores
Started 15,000 years ago • Small semi-sedentary
communities
• Stone tools
• Early agriculture
• Early art
15
Domestication Cultivation of cereal grain
• Wild populations have normal retention frequency distribution
• Planting of grains remaining in ears • Crop population mean with higher retention
• Crop populations become more profitable to collect www.geog.ucsb.edu
Seed retention Fr
eque
ncy
Consequences • More control over food supply and quality • Larger, sedentary human populations • Reliance on resources, technology and knowledge • Danger of resource depletion (and over-harvesting in non-seed crops)
Seed retention
Freq
uenc
y
Harvested
16
Ancient agriculture
Started 5,000 years ago • Larger villages, cities
• Large-scale agriculture
• Metal tools
• Soil cultivation, irrigation
• Food storage
• Burocracy www.touregypt.net
Social structure: large non-family groups Food: local produce, storage Problems: predators, resource depletion, rival clans Innovations: domestication of vegetables, fruit trees, cats
17
Medieval agriculture
http://medieval.ucdavis.edu
Started 1,500 years ago • Feudal relations
• Large cities, manors
• Large-scale agriculture
• Sustenance and profit
• Plowing, fertilization
Social structure: feudal (serfdom) Food: local produce, storage, import Problems: food shortage, desease Innovations: selection, work
differentiation
18
Modern agriculture
www.stolaf.edu
Started 200 years ago • Population increase
• Land development
• Production maximization
• Mechanization
• Profit
Social structure: family business Food: local produce, storage, import, industrial processing Problems: pests, pollution, subsidies, capital investment, scale enlargement, uniformity Innovations: science-based, hybrid crops
Crop trait selection
19
http://www.doctortee.com/
Genotype-environment interactions (G×E)
• Reaction norms for 2 phenotypic traits (a,b)
• Trade-off between the traits (c) • Physical/physiological trade-offs:
Limitation of selection (d)
Selection for desired phenotypic traits • Crop diversity • Market value • Genotypes adapted to different