An e-publication by the World Agroforestry Centre

AN INTRODUCTION TO AGROFORESTRY

SECTION II
AGROFORESTRY SYSTEMS AND PRACTICES

Chapter 3
Classification of agroforestry systems

If we look at existing land-use systems using the broad definition and concepts of agroforestry given in Chapter 2, we find that various types of agroforestry combinations abound in all ecological and geographical regions of the world, but most distinctively in the tropics. Several descriptions of very promising land-use systems involving integrated production of trees and crops, as well as innovative scientific initiatives aimed at improving such systems, have been reported without the label of "agroforestry" before the arrival and acceptance of this new word. The extent and distribution of agroforestry systems are discussed in Chapter 4.

In order to understand and evaluate the existing agroforestry systems and to develop action plans for their improvement, it is necessary to classify them according to some common criteria. The most organized effort to understand the systems has been a global inventory of agroforestry systems and practices in developing countries undertaken by ICRAF between 1982 and 1987. This activity involved systematically collecting, collating, and evaluating data pertaining to a large number of such land-use systems around the world (Nair, 1987a). It assembled for the first time, a substantial body of information on a large number of agroforestry systems including their structures and functions, and their merits and weaknesses. This information was so comprehensive and broad-based that, on the one hand it provided an elaborate database for developing a widely-applicable classification scheme, and on the other hand, such a classification scheme became necessary to compile and process the information. Nair (1985a) used this information to develop the classification scheme described here.

The main purpose of classification should be to provide a practical framework for the synthesis and analysis of information about existing systems and the development of new and promising ones. Depending on the focus and emphasis of strategies for development of improved systems, the nature of a given framework will vary. Therefore, any classification scheme should:

  • include a logical way of grouping the major factors on which production of the system will depend;

  • indicate how the system is managed (pointing out possibilities for management interventions to improve the system's efficiency);

  • offer flexibility in regrouping the information; and

  • be easily understood and readily handled (practical).

The complexities of these requirements suggest that a single classification scheme may not satisfactorily accommodate all of them; perhaps a series of classifications will be needed, with each one based on a definite criterion to serve a different purpose. In the early stages of agroforestry development, several attempts were made to classify agroforestry systems (Combe and Budowski, 1979; King, 1979; Grainger, 1980; Vergara, 1981; Huxley, 1983; Torres, 1983). However, these were mostly exercises in concept development rather than aids in evaluating and analyzing agroforestry systems based on field data. While some of them were based on only one criterion such as the role of components (King, 1979) or temporal arrangement of components (Vergara, 1981), others tried to integrate several of these criteria in hierarchical schemes in rather simple ways (Torres, 1983) or more complex ones (Combe and Budowski, 1979; Wiersum, 1980).

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: refers to the composition of the components, including spatial arrangement of the woody component, vertical stratification of all the components, and temporal arrangement of the different components.

  • Functional basis: refers to the major function or role of the system, usually furnished by the woody components (these can be of a service or protective nature, e.g., windbreak, shelterbelt, soil conservation).

  • Socioeconomic basis: refers to the level of inputs of management (low input, high input) or intensity or scale of management and commercial goals (subsistence, commercial, intermediate).

  • Ecological basis: refers to the environmental condition and ecological suitability of systems, based on the assumption that certain types of systems can be more appropriate for certain ecological conditions; i.e., there can be separate sets of agroforestry systems for arid and semiarid lands, tropical highlands, lowland humid tropics, etc.

These broad bases of classification of agroforestry are by no means independent or mutually exclusive. Indeed, it is obvious that they have to be interrelated. While the structural and functional bases often relate to the biological nature of the woody components in the system, the socioeconomic and ecological stratification refers to the organization of the systems according to prevailing local conditions (socioeconomic or ecological). The complexity of agroforestry classification can be considerably reduced if the structural and functional aspects are taken as the primary considerations in categorization of the systems and socioeconomic and agroecological/environmental (as well as any other such physical or social) factors are taken as a basis for stratifying or grouping the systems for defined purposes. These approaches to classification of agroforestry systems are summarized in Table 3.1.


Table 3.1. Major approaches to classification of agroforestry systems and practices.

3_classification_of_agroforestry_systems
* See Figure 3.2. (on p. 27) for explanation of these terms
Source: Nair (1985a).