Prevent monocultures while combating erosion through reforestation

A monoculture is the cultivation of one species (e.g. one variety of trees).  Limited to only one variety, this type of planting has a very bad influence on ecology.  If there is only one variety, only a few animals can live from it, and naturally complex lifecycles become impossible. This often results in plagues and infestations, as the system lacks natural enemies which normally balance excessive (and damaging) populations of other fauna (e.g. larger animals, smaller pathogens, etc.).

The current practice of planting large areas (i.e. 10's of 1000's of hectares) as a monoculture (e.g. only Eucalyptus, or only Acacia), will become a bigger disaster for the environment than savannas now are!  In the case of monocultures, it is better to have a 'barren' desert than a 'green' monoculture desert.

Solution

The establishment and productivty of forests can be much greater if we choose for a mix of ecologically and economically interesting trees:

  1. Ecologically interesting trees on areas where harvesting is difficult (i.e. gaps, ravines, escarpments, really poor soils);
  2. Economically interesting trees in combinations (e.g. fruit, nuts, wood products, varieties supporting wildlife, etc.);
  3. High-growing trees in combination with low-growing bushes and/or shrubs producing fruit;
  4. High-growing trees with 5 - 10 varieties all having naturally symbiotic growing qualities;
  5. High-growing trees divided into different rates of growth (e.g. fast, slower and very slow growing).  First harvesting the fastest, and finally, the slowest growing varieties;
  6. The slowest-growing should ideally be high-growing varieties, which enables other trees to grow below them.

Suitable trees for combined growing

The following is a list of trees suitable to prevent monocultures (Source document ‘Wood Energy’ FAO – Unisylva - editor T.M. PASCA):

Species Ecosystem Fw* Ti* L.f.w.* Other uses Method of propagation Annual rainfall and climatic/soils conditions

1. Acacia arabica

Windbreaks
Shade trees
Bush-fallow

XX

 

X

Pods as fodder

Direct seeding on mounds, strip or line

Alluvial or loamy soil; moist conditions

2. Albizzia falcataria

Shade trees
Regular planting in farm forestry

XX

XX

X

 

Direct seeding or seedlings raised in nursery

Wide range of soils, but prefer loamy soil and good rainfall

3. Bamboo (several spp.)

Live fencing
Regular plantations in farm forestry
Around houses

X

X

XX

Raw material for cottage industries
Shoots for food

Rarely from seeds
Shoot cuttings

Loamy or clayey soil; moderate to high rainfall

4. Calophyllum inophyllum

Shade trees for amenity (roadsides, around houses, public gardens)

 

XX

 

Burning oil

Seedlings to be raised in nursery

Loamy/clayey soil; moderate to very moist conditions

5. Cassia siamea

Shade trees in plantations

XX

X

   

Direct sowing of seed in lines

Heavy rainfall (poor growth in dry climate)

6. Casuarina equisetifolia

Agri-forestry systems
Windbreaks

XX

XX

X

Tannin bark

Seedlings raised in nursery. Planting (1.5- to 2-m spacing) or if too close, early thinning needed

Sandy soil; stand rainfall between 800 and 5 000 mm

7. Combretum quadrangulare

Rice field dikes

XX

 

X

Medicine

Seedlings raised in nurseries. Direct seeding possible

Loamy soil; slower growth on sandy soil; average rainfall 1500 2 000 mm over 5/6 months

8. Cordia alliodora

Agri-forestry systems
Shade trees in coffee plantations

 

XX

X

 

Direct seeding (mixed success)
Seedlings from nursery - wide spacing (unless early thinning)
Natural regeneration good

Moist, well-drained sites; rainfall 1500-2000 mm

9. Glyricidia spp.

Shade trees in plantations or as living stakes

X

 

X

 

Direct seeding or stumps

Alluvial or clayey soil; high rainfall or moist conditions

10. Grevillea robusta

Shade trees in tea and coffee plantations
Roadside trees

 

XX

   

Seedlings from nursery

Sandy soils; 700 to 1 500-mm summer rainfall

11. Leucaena glauca

Windbreaks
Shade trees
Planting around houses

XX

 

X

Fodder
Green manure
Nitrogen fixing

Direct seeding or cuttings

Neutral or alkaline soils, poor growth on acidic houses soil; rainfall 600-1 700 mm

12. Morus indica (M. alba)

Regular plantations for silkworm raising
Irrigated roadside or canal planting

X

X

 

Fruit leaves for silkworm raising

Direct seeding or branch cuttings

Light sandy soil. Moderate to high rainfall (18002 500 mm) or canal planting

13. Pithecellobium saman

Shade/amenity trees

XX

X

 

Fodder
Medicine

Direct seeding or seedlings from nursery

Clayey or loamy soil; high rainfall; moist conditions

14. Prosopis spp.

Plantations for fuelwood
Bush-fallow

XX

 

X

Fodder

Direct seeding (if irrigated) or stump planting

Dry soil, not excessive moisture; grows on rocky and saline soils

* Firewood, timber, light farm wood.

Downloads and links

Read all about preventing monocultures in this document from the FAO.

Read some articles about the negative effects of monocultures:

Monoculture tree plantations are ''green deserts'', not forests, say activists - by Jeremy Hance.

Fast-growing poplars may be a profitable way to reforest China, but artificial, single-species forests are unattractive and ecologically unsound, writes Jiang Gaoming.

'Sustainable' Green Deserts by Corporate Watch.