Agroforestry Chapter 7 (Part 1): Selection of Tree and Crop Species and Multipurpose Trees (MPTs)
Agroforestry Notes · Chapter 7 · Part 1
Chapter 7 (Part 1): Species Selection and Multipurpose Trees
Climate-, soil- and biotic-wise choice of trees, desirable traits of agroforestry trees and crops, nitrogen-fixing trees, and MPT definitions, benefits and ideal characteristics.
1. Choosing trees by climate
Trees and crops compete for nutrients, moisture and light, so only compatible components should be combined. Three factors govern species selection: climate, soil and biotic factors (grazing, fire, insect pests).
| Climatic zone | Suitable trees |
|---|---|
| Hot desert | Prosopis cineraria, P. chilensis, Acacia tortilis, Capparis, Tecomella undulata |
| Cold desert | Populus nigra, P. ciliata, P. alba, P. euphratica, Salix alba, S. fragilis, Juniperus |
| Tropical semi-arid | Prosopis, Acacia tortilis, A. nilotica, A. senegal, Albizia lebbek, Eucalyptus camaldulensis, Azadirachta indica, Salvadora persica |
| Subtropical semi-arid | Pinus roxburghii, Acacia modesta, Albizia procera, Bauhinia variegata, Morus, Ficus |
| Temperate semi-arid | Pinus gerardiana, Juniperus macropoda, Corylus colurna |
| Tropical sub-humid | Eucalyptus tereticornis, Casuarina equisetifolia, Dalbergia sissoo, Leucaena, Populus deltoides, Moringa oleifera |
| Humid tropical | Tectona grandis, Terminalia, Gmelina arborea, Dipterocarpus, Cocos nucifera, Areca catechu, Artocarpus, Pterocarpus santalinus |
| Temperate semi-humid | Acacia mearnsii, Alnus nepalensis, Cedrus deodara, Juglans regia, Celtis australis |
| Humid temperate | Abies pindrow, Quercus, Robinia pseudoacacia, Pinus wallichiana, Alnus nitida, Populus ciliata, Cryptomeria japonica |
2. Choosing trees by soil
| Soil | Suitable trees |
|---|---|
| Desert soil | Prosopis cineraria, P. chilensis, Acacia tortilis, A. senegal, Salvadora |
| Recent alluvium (riverain) | Acacia catechu, Dalbergia sissoo, Bombax ceiba |
| Saline-alkali | Prosopis juliflora, Acacia nilotica, Azadirachta indica, Ailanthus, Eucalyptus, Tamarix, Pongamia pinnata |
| Coastal and deltaic alluvium | Casuarina equisetifolia, coconut, arecanut, Avicennia |
| Red soils | Tectona grandis, Madhuca indica, Mangifera indica, Leucaena, Pterocarpus marsupium, Dendrocalamus strictus |
| Black cotton soils | Acacia nilotica, A. leucophloea, Tectona grandis, Hardwickia binata, Tamarindus indica, Aegle marmelos |
| Laterite soils | Acacia auriculiformis, Tectona grandis, Eucalyptus, Azadirachta indica, Emblica officinalis |
| Peaty / organic soils | Syzygium cumini, Ficus glomerata, Bischofia javanica, Lagerstroemia speciosa, Gliricidia |
| Hill soils | Juglans regia, Alnus nitida, Toona serrata, Cedrus deodara, Quercus, Grewia optiva, Celtis australis |
Memory trick: Riverain colonisers K-S-S: Khair (A. catechu), Shisham (D. sissoo), Semal (Bombax). Black cotton = Hardwickia (anjan).
3. Desirable traits of trees and crops
Roots
- Deep taproot; low water need
- Roots explore layers different from crop roots
- Quick regeneration of laterals after transplanting
Crown
- Light branching so sunlight reaches crops
- Withstands pruning, lopping and pollarding
- Small, quickly decomposing leaves (broad leaves of teak, mango, banyan not preferred)
Soil
- Builds fertility; N-fixing legumes preferred
- Good nutrient cycling
- Free from allelochemicals
Growth and use
- Fast growth and short rotation (poplar, Casuarina, Leucaena)
- Palatable, digestible fodder
- Multiple uses and high yield potential (most important)
- Thin bark not shed regularly
Desirable traits of crops
- Short duration, quick growing and at least partly shade-tolerant.
- Mostly from Leguminosae; respond to high-density tree planting.
- Tolerate water stress or excess water; return organic matter to the soil.
- Common shade-tolerant crops under trees: turmeric, ginger, colocasia, cowpea and fodder grasses.
Nitrogen-fixing trees (from the e-course list of 46)
- Acacia: A. albida, A. auriculiformis, A. catechu, A. mearnsii, A. nilotica, A. senegal, A. leucophloea, A. melanoxylon, A. dealbata.
- Albizia chinensis, A. lebbek, A. procera; Alnus nepalensis, A. nitida (non-legumes, Frankia).
- Bauhinia variegata, Butea monosperma, Cassia fistula, C. siamea, Casuarina equisetifolia (non-legume, Frankia).
- Dalbergia latifolia, D. sissoo, Delonix regia, Gliricidia sepium, Hardwickia binata, Leucaena leucocephala.
- Moringa oleifera, Ougeinia oojeinensis, Parkinsonia aculeata, Peltophorum, Pithecellobium dulce.
- Prosopis alba, P. chilensis, P. cineraria, Robinia pseudoacacia, Samanea saman, Saraca indica, Sesbania spp., Tamarindus indica.
Exam point: This is the e-course’s list as given; it also names a few trees (Cassia, Tamarindus, Moringa) whose nodulation is doubtful in other sources. Quote the e-course in course exams.
4. Multipurpose trees (MPTs)
Multipurpose tree species (MPTs)The multipurpose tree species (MPTs) is a plant species that is purposefully grown so as to provide two or more than two products and also service function like shelter, shade, land sustainability of the land-use system. Many woody perennial species may be ‘multipurpose’ in one kind of system but ‘single purpose’ in another.Source: ICAR e-course, Introductory Agroforestry
Multipurpose trees (Nair, after Burley and Wood, 1991)"those trees and shrubs which are deliberately kept and managed for more than one preferred use, product, and/or service; the retention or cultivation of these trees is usually economically but also sometimes ecologically motivated, in a multiple-output land-use system."Source: Nair (1993), An Introduction to Agroforestry, Chapter 12
PhreatophyteIs a deep-rooted plant that obtains a significant portion of the water that it needs from the phreatic zone (zone of saturation) or the capillary fringe above the phreatic zone.Source: ICAR e-course, Glossary
Nair: “All trees are said to be multipurpose; some, however, are more multipurpose than others.” The MPT is the most distinctive component of agroforestry. Sources of MPT data include the NAS “Firewood Crops” (1980, 1983), von Maydell (1986) for dryland Africa, and ICRAF’s MPT database.
| Benefit | Examples |
|---|---|
| Food | Human food, livestock feed; fertiliser trees through N-fixation, deep rooting, higher CEC |
| Water | Better moisture retention, regulated stream flow; phreatophytes drain waterlogged or saline soils |
| Energy | Firewood, pyrolysis products, producer gas, ethanol from fruits, methanol from wood, oils and latex; trees can boost wind power by a venturi effect (power ∝ velocity³) |
| Shelter | Building material, shade, windbreaks, shelterbelts, living fences |
| Raw materials | Craft wood, weaving fibre, fruits and nuts, tannins, essential oils, medicines |
| Cash and social | Direct and indirect income; social uses such as bride price and ceremonial foods |
Characteristics of an ideal MPT
- Wide adaptability and a thin, sparse crown letting light into the system.
- Withstands coppicing, lopping and pollarding; sprouts quickly.
- Productive: poles, wood, food, fodder, medicines.
- Leaf litter releases nutrients in time with the crop cycle.
- Few shallow (prunable) laterals and a deep thrusting taproot.
- N-fixation; tolerance of drought, flood and soil variability.
- Easy to manage, cheap to establish, good market demand.
5. More on MPTs from Nair (Chapter 12)
- Nair defines agroforestry species by their amenability to intercropping, and uses MPTS for multipurpose trees and shrubs.
- Information sources: NAS “Firewood Crops” (1980, 1983), prepared by a BOSTID panel; ICRAF’s MPT database (von Carlowitz, 1991) on about 1,100 species; Winrock’s MPT compendium for Asia (Lantican and Taylor, 1991); von Maydell (1986) for dry Africa.
- About 50 MPTs are widely used in agroforestry, whereas about 30 food species feed most of the world (Borlaug and Dowswell, 1988). Homegardens hold about 250 woody species (Fernandes and Nair).
- Le Houérou (1980) called woody fodder plants “trubs”. The main nutritive value of tree fodder is its protein (Torres, 1983).
| Fodder tree | Crude protein (% of dry matter) |
|---|---|
| Erythrina poeppigiana | 32.0 |
| Gliricidia sepium | 27.6 |
| Sesbania grandiflora | 26.9 |
| Sesbania sesban | 26.4 |
| Erythrina variegata | 25.7 |
| Paraserianthes falcataria | 24.0 |
| Albizia lebbek | 22.1 |
| Leucaena leucocephala | 22.0 |
| Cajanus cajan | 21.7 |
| Robinia pseudoacacia | 20.7 |
| Dalbergia sissoo | 16.6 |
| Azadirachta indica (neem) | 15.0 |
| Faidherbia albida | 14.3 |
| Prosopis cineraria | 13.9 |
| Acacia nilotica | 13.6 |
| Terminalia arjuna | 10.0 |
NDF (neutral detergent fibre) = hemicellulose + cellulose + lignin; ADF (acid detergent fibre) = cellulose + lignin
Ideotypes
An ideotype is “a form denoting an idea” (Donald, 1968): the ideal plant type for a given use. For MPTs the idea was developed by Dickmann (1985) and Wood (1990). Nair gives an ideotype of Acacia tortilis for semi-arid areas, ranked fodder first, then fuel and food. Budelman (1991) described an ideotype for yam-stake trees. On exotics vs natives, Wood (1990) says choose the most suitable species, whatever its origin.
Palms in agroforestry
- Coconut, arecanut
- Babassu (Orbignya), Brazil
- Carnauba wax palm (Copernicia prunifera), north-east Brazil
- Pejibaye or peach palm (Bactris gasipaes)
- Johnson (1984) listed 52 useful palm species
Lesser-known fruit trees
- Brazil nut, guarana, cupuaçu (Amazon)
- Durian (South-East Asia)
- Tomé-Açu (Brazil): 32 fruit species in agroforestry
- FAO (1983): about 700 food species for emergencies
Memory trick: Highest crude protein: Erythrina poeppigiana 32; lowest in the table: Terminalia arjuna 10. Leucaena is about 22.
6. Quick revision box
- Selection factors: climate, soil, biotic.
- Cold desert: Populus, Salix alba; hot desert: Prosopis cineraria, Tecomella.
- Temperate semi-arid: Pinus gerardiana; coastal: Casuarina; black cotton: Hardwickia; laterite: A. auriculiformis.
- Most important tree trait: high yield potential; broad leaves (teak, mango, banyan) not preferred.
- Crops: short-duration, shade-tolerant, mostly legumes.
- Non-legume N-fixers: Alnus, Casuarina (Frankia).
- MPT: two or more products + service; Burley and Wood (1991) definition in Nair.
- Phreatophyte draws water from the zone of saturation; wind power ∝ v³.
- ICRAF MPT database (von Carlowitz 1991) ~1,100 spp; NAS “Firewood Crops” (BOSTID).
- Crude protein: Erythrina poeppigiana 32, Gliricidia 27.6, Leucaena 22, D. sissoo 16.6, neem 15, T. arjuna 10.
- NDF = hemicellulose + cellulose + lignin; ADF = cellulose + lignin. Ideotype: Donald (1968).
7. Interactive MCQ Quiz
22 questions. Tap an option to see the answer and explanation, then go to the next question.
Comments
Post a Comment