Introductory Agroforestry

Different Agro-forestry Systems

Different types of agroforestry systems exist in different parts of the world. These systems are highly diverse and complex in character and function. Classification of agroforestry systems is necessary in order to provide a framework for evaluating the systems and developing action plan for their improvement. Several criteria can be used in classifying them but most common includes the system structure, function, socioeconomic scale of management, ecological spread etc. According to the potential, there are many different systems of agroforestry. In agroforestry the terms like system, sub-system and practices are commonly used. Therefore, these terms require proper definitions in agroforestry languages:
System:

• System refers to a group of physical components, i.e. an assemblage of objects connected or related in such a manner so as to form and/or act as a unit; e.g. ecosystem which consists of living organism and their non-living environment with which they are inseparably interrelated.
• In land use terms, a system refers to a type of land use specific to an area and described according to its biotechnical composition and arrangement, level of technical management of socio-economic features; e.g. rice production system, plantation crop systems.
Sub-system:

• Sub-system indicates a lower order hierarchy of the system.
• It refers to a part of system, with more or less restricted role, content and complexity than the system itself.
• A sub-system produces a defined ‘basic needs’ as its major output, so that there can be a food sub-system, an energy production sub-system and cash sub-system.
Practices:

• Practices in agroforestry denote specific land management operations of any nature, carried out on a farm or other management unit.
• Such practices are involved in the constitution and maintenance of an agroforestry system; e.g. alley cropping, boundary plantations of trees and shrubs, shelterbelts and windbreaks, etc.
Why classification:

• It includes logical way of grouping the major factors on which production of the system will depend
• It indicates how system is managed
• It offers flexibility for regrouping the information
Criteria/Basis for Agroforestry System Classification

Combe (1982) proposed 24 agroforestry systems based on three type of association of the trees with crops, with pastures and with both crops and pastures); two major functions of the tree components (production and protection); two spatial arrangements (regular and irregular); and two types of temporal association (temporary and permanent).
The most obvious and easy-to-use criteria for classifying agroforestry systems are the spatial and temporal arrangement of components, the importance and role of components, the production aims or outputs from the system, and the social and economic features. They correspond to the systems' structure, function (output), socioeconomic nature, or ecological (environmental) spread. These characteristics also represent the main purpose of a classification scheme. Therefore agroforestry systems can be categorized according to these sets of criteria:

• Structural basis
• Functional basis
• Socioeconomic basis
• Ecological basis



Fig. 3.1(a) Agroforestry systems classification, Combe (1982)

Fig. 3.1(b) Agroforestry systems classification, Combe (1982)

Fig. 3.2 Agroforestry system on relative allocation of land for components

Vergera (1982) considered the relative allocation of land, trees, crops, pastures in various agroforestry systems.


Fig. 3.3 Agroforestry systems on basis of relative dominance of components

Tejwani (1987) suggested a classification which among the other things also took into account relative dominance of trees or crops/pastures


Fig. 3.4 Agroforestry systems based on different criteria