Thought experiments can provide insight into complicated systems. This one may provide an interesting way of looking at agroforestry research. Imagine three groups of researchers: the first is composed entirely of horticulturists specializing in tree crops (A), the second of silviculturists (F), and the last a mixture of individuals from both groups (AF). All individuals in the experiment are selected for their ability to collaborate both across and within professions. We give each of the three groups the identical assignment of constructing a cropping system. The only rules for constructing the cropping system are that it must consist of a mixture of tree and non-tree crops and that it is integrated, intensive, intentional and interactive (the four I’s of agroforestry). We then replicate the experiment many times. That is, we maintain the A, F, and AF groupings, keep the same assignment, but use new personnel with each replication.
The important questions to ask about this thought experiment are:
- What criteria should be used to compare the cropping systems developed by each group?
- Is there a similarity in the cropping systems constructed from within a group?
- Conversely, can we detect meaningful betweengroup differences in the cropping systems constructed?
Cropping system differences may be found in the type of agroforestry (e.g., alley cropping, forest farming, etc.), the choice of crops, the complexity of the system, and the reliance on external inputs. For example, we may find that the A group hesitates to consider using forest species such as oaks, pines or black walnut. Perhaps, they would intercrop a vegetable or hay crop within a traditional orchard crop (almond, apple, peach, etc.) and try to reduce the competition effects between these crops through irrigation, fertilization and spacing.
The F group may be more willing to use nontraditional crops (e.g., ginseng) and look to species like oaks, pines or black walnut. They may be more likely to reduce competition between crops by choosing crops that occupy different ecological niches or that interact positively before relying on supplemental inputs as a remedy.
If we answer questions 2 and 3 positively then we are postulating that the cropping systems are not samples from a single population. That is, we are expecting the groups to produce different cropping systems and therefore we should not pool them together. However, if we maintain that we should answer questions 2 and 3 negatively then our expectation is that they are samples from a single population.
If we believe important differences in the cropping systems constructed would exist, then we need to decide whether the cropping systems from each group should be considered agroforestry. Also, our description of agroforestry research should make these potential differences apparent.
In particular, how does the placement of both horticulturists and silviculturists within the same group affect the cropping system constructed? And, do these cropping systems have attributes that make them more desirable than those constructed by the other two groups? If so, then we are inferring that agroforestry is an integration of professions as much as it is an integration of plant species. Perhaps it is time to consider the nature of the working relationships between these two professions in developing agroforestry.
Thought experiments are necessarily speculative and they generate no data. However, they do provide a good means of checking our logic for internal inconsistencies, developing hypotheses, and suggesting strategy. As in real experiments, worthwhile thought experiments require skill to conduct. In our experiment we examine the roles of horticulturists and silviculturists in agroforestry, therefore the minimum required skills are expertise in our own field and the ability to dialog meaningfully with those in other fields. Each of these professions has its own philosophy for managing plant productivity. Recognizing professional differences is the first step toward working together for a common cause.
An excellent way to begin the dialog is to encourage horticulturists to join AFTA and for silviculturists interested in agroforestry to join the American Society for Horticultural Science and establish an agroforestry working group within this organization.