Tree-Based Agroforestry Systems Summer term 2007, rationale (June 17th)

Course Credit: 1 SWS (1.5 credits ECTS) within the Module Forest Protection & Agroforestry

Examination: Written, date 15. Aug. 2007

Lecture by: Dr. Uwe MuussCentre for Tropical and Subtropical Agriculture and Forestry (CeTSAF)Büsgenweg 137077 Göttingen, GermanyEmail: umuuss@gwdg.de

Global indicators 1950 2000 IncreasePopulation (billion) 2.5 6.1 > doubleEconomy (trillion $, 2001)

7 46 > seven-fold

Grain production (million tons)

640 1855 ~ Tripled

Area under cultivation(million ha)

603 660 9.5%(accounts for 30% of total increase)

Grain yield (Mg/ha) 1.06 2.79 160%

Agricultural Production, 1950 – 2000

Source: P.K. Nair, 2006

World Cereal Production, 1961 - 2004

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2500

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Total Production 1961 - 2004 0

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500

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Per Capita Production 1961 - 2004

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Total Yield Per Hectare 1961 - 2004 500

600

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800

1960 1970 1980 1990 2000 2010

Mill

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Total Area Harvested 1961 - 2004

Source: FAOSTAT data, 2005.

Per Capita Production

Total area Harvested

Total Production

Total Yield per Hectare

Areas Saved through Improved Technology – World Cereal Production (Borlaug)

Source: http://www.usda.gov/oce/forum/speeches/borlaug.pdf

World fertilizer use, 1950-99

Pesticide use in the world and the US

Degraded land in developing nations = ca 2.0 billion ha, 1/3 of total farmland

�Water erosion = 56%�Wind erosion = 28% �Physical deterioration = 12% �Chemical deterioration = 4%

High soil salinity levels in ~ a billion ha (7% of total land); an estimated 3 ha of land is becoming non-productive every minute because of salinity.

Degradation is slight in 38% of these lands, 40% are moderate, 15% severe, and 0.5% extreme.

Soil Degradation in Developing Countries

Source: Adapted from Scherr (1999)

Current situations are alarming in many countries of Africa and Asia

Pictures: PK Nair

Agriculture has a Vast Impact on the Earth

� Over two-thirds of human water use is for agriculture

� Crop and livestock production is the main source of water pollution by nitrates, phosphates and pesticides

� Agriculture, forestry and fishing are the leading causes of loss of the world's biodiversity

� Agriculture affects the basis for its own future through land degradation, salinization, the overextraction of water and reduction of genetic diversity

� The long-term consequences are difficult to quantify.

Is it great progress?

– But to succeed – farmers have to get bigger• UK: 200,000 farms lost in 50 yrs (11/day)• USA: 4 million farms lost in 50 yrs (219/day)

Modern industrialised farming looks good because it measures its own success narrowly - and ignores the costly side-effects

Source: PK Nair 2006

Food Production Per Person (1961 = 100) 1961 - 2000

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220

240

1960 1965 1970 1975 1980 1985 1990 1995 2000

Asia (developing)

Latin America and the Caribbean

Sub-Saharan Africa (excluding South Africa)

World

Food Production Per Person. Source: FAO, 2000 (modified).

Getting Hungrier?

The Gap is Widening

• In 1960 average per capita income in industrialized nations was nine times the average of Sub- Saharan Africa

• Today it is 18 times

Difference in magnitude

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5

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1960 2000

Sub-Saharan AfricaIndustrialized Nations

GLOBAL FORESTS:

Tragedy of the Commons?

World Forest Distribution

40.0%29.1%

10.9%

20.0%

Tropical Forest

Temperate Forest

Temperate Woodlands

Tropical Woodlands

Global Forest Area: Past and Present

Adapted from FAO: http://www.un.org/esa/population/publications/wpm/wpm2001.pdf

6511178Oceania3227826Excl. Russia

58427323Europe67395720L A C 78455819N. America

28144931Asia

3482330Africa

542648130World

% of original forest

% of land area

% of land area

Land area (mill. km2)

Total remaining forestOriginal forest

Are

a un

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fore

st (R

elat

ive)

Time

Unlimitedresource

No danger ofdepletion

Someclearancewelcomed

Reduction inarea Voices for

conservation Legislation,govt. action

Pattern of Forest Utilization in Time

1960 1970 1980 1990 2000

Exploitation

Plantations

Social Input

Agroforestry

CommunityForestry

Social Forestry

Urban Forestry

Environmentalconcerns

Climate Change

Biodiversity

NTFP

HabitatProtection

Tropical Forestry:Issues, Initiatives, Paradigms

? ? ?

Forest/timberCertification

Ecotourism

For most policy makers, forest means timber

But forest and forestry mean much more than that …

Global Forest Goods and ServicesCommodities and Products

TimberFuelIndustrial products

Non-timberEdible plants, nuts, etc.Medicinal productsFloral productsAnimal productsOther fiber productsForage

ServicesEnvironmental

LocalSoil protectionWater qualityGenetic and biotic

ConservationPollution bufferingGlobalCarbon storageGenetic & biotic cons.

Leisure and other Outdoor recreationAestheticsOther intangibles

Plantation Forests

A forest raised artificially � Usually of a regular shape� Intensively managed� No. of species less, often one� Biologically less complex, but

economically more attractive� Only 5 % of world’s forest, but provides

about 50% of the world's wood

Teak (Tectona grandis) in southeast Asia

Sal (Shorea robusta) in India

Eucalyptus in Brazil

Plantations: a major form of forestry development

Cryptomeria pix from Kitayamasugi taken from web

sites, addresses sent by Maasaki Yamada

Japanese cedar, Cryptomeria japonica: Perhaps the highest intensity silvicultural operation in the world

HIGH INTENSITY FORESTRY, Dehra Dun, India

Tropical Forestry:The Conservation / Production Dilemma

Forests in wilderness

areas

Conservation reserveforests

Managed old growth forests

Intensively managedregrowth forests

Plantation andfarm forestsC

onse

rvat

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Valu

e

Production Value

Max

. ----

Mgt

. ----

Min

.in

tens

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Fuelwood

More than 50 % of the wood produced globally is used as firewood/charcoal

“Small timber”: not a part of global trade

Zimbabwe Haiti

Fodder

Cattle, an asset in many societies, are supported by tree fodder

Disturbance, conversion, or destruction

Rates:� 1850-1980: 15%, globally� Currently, tropical deforestation (15 million

ha/yr; 1%) is a matter of great concern

Deforestation

Sustainability …

� not compromising future generations’ needs

� balance between ecology, economics, social justice

Many modern land-use systems of agriculture and forestry do not meet the sustainability criteria

Furthermore, high-input land-use systems have bypassed resource-poor conditions and ignored multiple benefits of traditional land-use systems

“The significant problems we face today cannot be solved at the

same level of thinking we were at when we created

them.”

The Way Ahead

Albert Einstein

TIME’s Person of the Century

AGROFORESTRYAn interface between

agriculture and forestry

… the purposeful growing of trees and crops and/or animals in interacting combinations for a variety of objectives.

Nair, 1984.

“Miracle trees” are grown on

farmlands, Africa.

Faidherbia albida in crop fields in West African

drylands

Intercropping: Acacia trees and rice + sesame; India

The Taungya System: Eucalyptus and rice; Thailand

Integrated multi-species land-use systems; Kerala, India

Homegardens: the epitome of sustainability

Tree fruits are a significant source of food and nutritional security

Bahia, Brazil: traditional land-use systems are a way of life in many societies

Shaded perennial system: coffee under shade; Costa Rica

Sun vs. Shade-grown CoffeeShade Sun

Av. yield (kg ha-1) 800 1200Plants/ha 1000 – 2000 > 2000Lifetime (yr) 25 – 30 12 – 15 Flavor (bitter) Less MoreProducers Small holders Large-scale# Bird species 150 20 – 50 Mid-size mammals 24 Almost noneOther species Abundant LessAgro-chemical use None or less HigherIrrigation Lower HigherSoil deterioration None/Lower Higher

http://www.ems.org/shade_grown/facts.html

Coffee~ 3300 cupsconsumedper second worldwide;US 33%.

The second most widely tradedcommodity(next to oil).

A multistrata system of peach palm (Bactris gasipaes), black pepper (Piper nigrum) and cacao (Theobroma cacao) in Bahia, Brazil

Under-exploited TreesA large number of underexploited trees that provide a variety of products are used in indigenous farming systems throughout the world

� Food (Fruit trees)

� Fertilizer (Nitrogen-fixing trees)

� Fodder (Fodder trees)

� Fuelwood (Firewood species)

� Medicinal and aromatic products

Alley cropping: tree hedgerows + crops; Africa

Fertilizer Trees African farmers interplantnitrogen-fixingtrees with crops to provide nutrients to crops and reducedependence on costly fertilizers

Olive trees + barley; Italy

Paulownia trees + wheat; China

Agroforestry Practices in North America Alley cropping Trees planted in single or grouped rows with

herbaceous crops in the wide alleys between the tree rows

Forest farming Utilizing forested areas for producing specialty crops that are sold for medicinal, ornamental, or culinary uses

Riparian buffer strips

Strips of perennial vegetation (tree/shrub/grass) planted between croplands/pastures and streams, lakes, wetlands, ponds, etc.

Silvopasture Combining trees with forage and livestock production

Windbreaks Row trees planted around farms and fields and managed as part of crop or livestock operation to protect crops, animals, and soil from wind hazards

Alley Cropping: Trees planted in single or grouped rows in herbaceous crops in the wide alleys between the tree rows

Ornamentals Specialty crops; Ginseng

Forest Farming; NY, USA

Silvopasture:Animals with trees

With pecan trees

With pines

Cattle and pasture under pines

With pines

Riparian buffer; IA,USA

“Before” “After”

Trees as windbreaks; NE, USA

The Coming of Age of Agroforestry

• Agroforestry has come of age during the past 25 years

• The traditional practices have been transformed into robust, science-based technologies

• AF is no longer “a practice in search of science”; it is based on scientific foundation

Eucalyptus + maize intercropping, Brazil Photo courtesy: Laercio Couto

Silvopasture (E. grandis) in Uruguay: Cofusa (Compania Forestal Uruguaya S.A.).

Photo courtesy: Timothy White.

The Dehesa of the western Mediterranean region: An extensive silvopastoral system (Animal grazing under scattered oak trees)

On-farm production of Eucalyptus grandis formeeting energy needs of tea factories in Kenya

Intercropping fruit trees (eg, mangosteen) and other valuable species (eg, sandalwood) with oil palm in Sabah, Malaysia

Sustainability and Agroforestry Systems

Ecological, Economic, and Social Factors

Ecological Sustainability• Enhancing productivity

� Soil Physical Conditions

� Soil Fertility

• Providing Ecosystem Services

� Biodiversity

� Carbon sequestration

� Water quality enhancement

Maintaining variation in genetic composition and a variety of species

For the purposes of conserving diversity through agroforestry systems, both geneticdiversity and speciesdiversity are important

Biodiversity

Carbon Sequestration• Extent of original C stock of the cleared forest regained

through land-use systems in the tropics:AF systems = 35 %; Croplands and pastures = 12 % (Palm et al., 2004).

• An increase of 1 Mg of soil C pool of degraded cropland soils may increase crop yields by 20 to 40 kg ha-1 (Lal, 2004).

• Projected C stocks for smallholder agroforestry systems:C sequestration rates of 1.5 to 3.5 Mg C ha-1 yr-1;Tripling of C stocks in a 20-yr period, to 70 Mg C ha-1.(Palm et al., 2004).

•Global deforestation, estimated to occur @ 17 mill ha yr-1, is expected to cause the emission of 1.6 Pg C ha-1 yr-1.

Carbon Sequestration in Soils: Silvopasure vs Treeless Pasture

• Total C greater in surface soils and less in deeper profile of pasture (bahiagrass) soils

• Little contribution by C3 plants in surface soils of bahiagrass pasture in the Spodosol

% of C contribution from C3 plants0 20 40 60 800

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Silvopasture

Treeless pasture

Studies on Spodosols in two counties of Florida, USA

Water Quality Enhancement• Nutrient-leaching rates from soils under AFsystems can be lower than those from treeless systems.

• The “safety-net” effect: The deeper and more extensive tree roots will take up more nutrients from the soil compared to crops with shallower root systems.

• The reduction of nutrient loading leads to water- quality enhancement in heavily fertilized agricultural landscapes. Consequently,

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Treeless (Alachua)

Silvopasture (Suwannee)

Treeless pasture (Suwannee)

Water soluble P (WSP)concentrationsby depth in silvopasture and treeless pasture sites on Spodosols in two counties (Alachua and Suwannee) in Florida, USA.

Riparian buffers for reclamation

of degraded croplands

Degraded cropland

… the same site, 15 years later

� Poverty Alleviation

� Food Security

� Deforestation

� Fodder- and Fuelwood Shortages

� Environmental Protection

� Land Degradation

� Income Generation

� Biodiversity Conservation

� Water Quality

� Social Quality of Life

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Agroforestry and the Top Ten Land-Use Challenges

Not a panacea … Agroforestry is certainly not a “cure-all” solution nor a substitute for commercial agriculture and forestry.

But, it is an appropriate approach in some situations, especially under low- input conditions.

Sustainable Agroforestry Systems for EnhancingProduction Benefits and Ecosystem Services

Sustainability

Ecological Factors Social Factors Economic Factors

and Agroforestry Systems

ENHANCINGFOOD and FIBER

PRODUCTION

N2 Fixation

NutrientCycling

Deep Capture of Nutrients

Improving Soil Physical Conditions

PROVIDINGECOSYSTEM

SERVICESSoilConservation

Carbon StorageWater Quality Enhancement

BiodiversityConservation

Agroforestry is an idea whose time has come …

As Mark Twain said:

“Twenty years from now, you will be more disappointed by the things you didn’t do than by the ones you did.”