O level Notes : Agriculture Forestry (Agroforestry) and wildlife

Agroforestry is the deliberate or planned growing of carefully chosen woody perennials on the same piece of land blended with agricultural crops and or animals.

The arrangement can either be in form of a spatial mixture or a sequential pattern. Agroforestry has been practiced for centuries in African and Zimbabwean traditional farming practices. This is a form of land use system which can give high agricultural productivity over a small or limited area.

The benefits derived from practicing agroforestry include harvest of both wood and food, animal fodder, wood for fuel, and utilization of a deeper soil volume through nutrient recycling where deep rooted leguminous trees are included. A carefully planned and blended tree crop and or animal production system in agroforestry practices can improve ecosystems, rehabilitate ecosystems and create sustainable productive ecosystems. There are many other benefits associated with agroforestry practices. However, if not properly planned, agroforest tree, crop, and livestock interactions may be negative. This results in reduced productivity of the land. The International Council for Research in Agroforestry (ICRAF) established in 1977 has made a lot of progress in research on agroforest components and interactions. Accurate information can now be obtained for planning and establishment of agroforestry systems. It is very important to make all necessary considerations for establishing an agroforestry system based on correct and accurate knowledge of the suitable tree, crops or animal interactions.

Wildlife commonly refers to a natural setting of wild animals in natural forests that are not negatively influenced by human activities. However, there are times when humans and wild life clash on their interests and needs resulting in conflicts. Conflicts between humans and wildlife normally arise when humans have some interests in the wildlife resources and animal habitat areas. Conflicts may also arise when wild animals encroach human settlement areas and interrupt activities or pose danger to life. The government of Zimbabwe has passed environmental laws to protect and promote sustainable utilization of wildlife resources and to minimize possible conflicts between humans and wildlife. The government is assisted in managing wildlife, carrying out citizen awareness or empowerment projects on wildlife by some voluntary organizations. The international conventions on wildlife management also help to set international regulations and agreements on wildlife resource management and challenges.

Agroforestry

Agroforestry, which is the integration of conventional crop production, livestock production and multipurpose forest or woody perennial trees is classified into systems basing on the functions or products of the integrated components. In the agroforest systems, the basic systems are silviagricultural systems, agrosilvicultural systems, silvopastoral systems and agrosilvopastoral. There are other tree animal systems such as trees with bee keeping (apiculture), trees with aquaculture (fish farming) and trees with insects such as Mopani worms. A lot of benefits can be derived from practicing agroforestry with the ever increasing population pressure on land.

The importance of Agroforestry practices

The integration of woody perennial trees, crops and animals results in environmental benefits, socio and economic benefits, depending on choices of component trees, crops and animals in the agroforestry system.

Products from agroforestry systems

• Wood and timber products
• Green manure and mulch
• Fruits and nuts
• Medicines
• Edible and industrial oil
• Charcoal
• Fruit or sap beverages
• Honey and beeswax
• Gum and resin
• Vegetables

Benifits of agroforestry system

Economic benefits

Agricultural enterprises should be sustainable and profitable. The practice of agroforestry greatly improves productivity of the land in a number of ways. These include:

• reduction of cropping system inputs such as fertilizers and weeding costs
• increased output of valuable tree products
• improved yields of crops in the system
• increased labor efficiency

Environmental benefits

• The agroforest trees take part in carbon sequestration which is the removal of carbon dioxide from the atmosphere. Forests act as carbon sinks.
• The woody tree component of the system provides shading and organic matter which assist in water conservation.
• Soil conservation is greatly enhanced in agroforest systems. This is so because the tree component provides leaf canopy and leaf litter which adds organic matter to the soil as well as reduce ground surface runoff. Soil erosion is reduced and soil fertility is maintained through efficient nutrient recycling.
• Agroforestry practice can be used to reclaim poor degraded soils and environments when suitable multipurpose trees are included.

Other benefits of an agroforestry set up

• Services provided by an agroforestry set up include aesthetic value from some trees that are ornamentals.
• Some component trees provide shade for humans and livestock.
• Trees planted bordering crop fields act as wind breaks and shelterbelts.
• Trees in some systems serve as live fences.

Types of agroforest systems

Agroforest systems are classified according to their function, nature of components and how these components are arranged in a system. The main basic agroforest systems are agrosilviculture, agrosilvopastoral, silviagriculture and silvopastoral.

There are other systems where trees can be blended with apiculture, aquaculture and insect breeding. Basing on component (trees, crops or livestock) arrangement, are simultaneous and sequential systems. An agroforestry system can exist as a simultaneous system where both components are present, the woody and non-woody components existing at the same time in the same field.

In sequential systems, woodlot phases are rotated with cropping phases such as in traditional shifting cultivation, where land was cleared of trees and cropped for some years and then left fallow for years to regenerate its vegetation and regain its fertility.

Agrosilvipastoral systems

In this system, there is integrated production of crops, trees and livestock. Most farm homesteads can have fruit trees, leafy vegetables and rabbits. There are set ups where tree bordering crop fields are combined with apiculture (bee keeping), aquaculture (fish farming) and mopani worm production or silk worms. Cattle can also be raised on stover and crop remains with some multipurpose trees included.

Trees and crops can have severe competition if not properly managed. The trees may need to be pruned or should be fed on by browser animals such as goats to minimize shading of crops in simultaneous systems (crops and trees established together). One method of minimizing competition between crops and trees is to use the sequential system where trees are alternated with crops in phases of 2-3 years, where land is not limited.

Agrosilvicultural systems

Agrosilvicultural systems involve the integrated production of crops and trees. The choice of the tree will depend on the function of the system. The trees may be for soil fertility management, to serve as wind breaks and shelterbelts around cropped lands in areas of high wind activities.

Multipurpose trees are planted in a linear arrangement bordering cropping lands. The trees will also suppress weed growth and reduce weed seed banks. This greatly improves weed management at a low cost.

Silviagricultural systems

In silviagricultural systems, trees are the dominant component with some crops. Established tree plantations are undersown with some crops. The choice of the crop must be a crop that is tolerant to shading or the plantation trees may be of the type that shade their leaves during crop growing period. Tree species such as Faidherba albida, which shades its leaves in summer, may be ideal for intergrating with summer grown crops.

Silvopastoral systems

Silvopastoral system is characterized by the integrated production of woody perennial trees and animals such as beef or dairy cows. The set up can be made of pasture lands, woody perennials that may be used as fodder feed for animals or the woody perennials may provide other wood products.

Agroforestry structure

Agroforestry structure refers to the arrangement and time of existence of components such as the trees and crops. There are two basic structural arrangements of components which are sequential and simultaneous.

Example

Sequential

Crops and trees do notexist at the same time.

• There is minimized direct competition between crops and trees. Crops and trees are planted in alternating
• successive phases.
• Shifting cultivation
• Woodlots are raised for some years and harvested, crops are then planted for 2-3 years on the same field and the cycle is repeated

Simultaneous

Crops and trees exist at the same time. Competition between trees and crops can be negative if not properly

managed and set up.

• Trees and crops existing in a mixed arrangement which can be dense or sparse
• A boundary arrangement of trees, with trees planted bordering cropping fields
• Linear arrangement where alternating rows or strips of trees and crops are established together Simultaneous agroforestry systems

Much attention should be given to simultaneous systems because if not properly arranged, interaction factors can negatively affect production.

Mixed arrangement of trees and crops

Mixed arrangement of trees and crops works well when the crops do not compete for resources or negatively affect each other.

Border arrangement of trees and crops

Growing trees bordering crops helps to reduce shading of crops and competition between crops and trees.

The bordering trees can be legumes which are pruned periodically adding organic matter to the soil. Trees planted at the crop field borders can also serve as wind breaks which reduce wind speeds that may harm crops.

Linear arrangement of trees and crops

Alternating crops and trees in strips helps to reduce competition and reduce negative interactive effects. This is so because the plants exist as individual stands.

Identifying agroforest systems and components In most smallholder farms and homesteads, some form of agroforest system is practiced but without much careful planning and emphasis. However, the agroforest systems already in existence in your community can be identified and be classified according to the identified components making the system.