Abstract. Agroforestry is not likely to be accepted, particularly by small-holders, unless
it is proved superior to other forms of land use not only on ecological but also on
economic grounds. It is therefore argued that economic parameters concerning the
quantitative productivity of all agroforestry systems components have to be a matter of
concern to both research and development in agroforestry.
In the process of screening selected relevant literature and as a result of a search of
ICRAF's Multipurpose Tree and Shrub Data Base, the yawning gap between the high
level of knowledge 9n agricultural crops on the one hand and the low level on woody
perennials on the other is exposed as a serious obstacle to the analysis of agroforestry
systems and to the further development of agroforestry. The lack of knowledge on
woody perennials, as substantiated in this paper, concerns particularly quantitative
production data on trees and shrubs used in agroforestry systems.
It is also argued in support of the views cited from other authors that what little
there is by way of yield data on woody perennials is scattered and distributed over a
vast amount of literature, and thus often difficult to access and to retrieve, and often
difficult if not impossible to compare owing to different methods and parameters
employed in attaining the data.
Although the difficulties of yield assessment are appreciated, increased efforts to
obtain more - and more comparable - data on the productivity of woody perennials
are advocated. In support of this call for stepping up appropriate activities some pre-
Uminary suggestions are presented on how to standardize parameters of yield assessments
to achieve better comparability and how to increase accessibility of yield data and
promote retrieval of data by the establishment of supplementary data bases.