Jonathan, In reply to your question and to David Thomson's comments:
A quick search of the literature should provide an adequate level of fertilizer to provide your trees for the establishment period. Maybe more important questions relate to how your choice could impact your results, if you choose to keep up such a regime for more than a short period. A constant amount of fertilizer provided over time could cause significant time-related variation due to differing relative growth rates among species. That is, without ~native soil conditions or near optimum nutrition (adjusted for plant size/leaf area through the experiment), the populations, or species that grow the fastest during early ontogeny will tend to become increasingly nutrient-limited later in the experiment. Regarding tree biomechanics (which truly have little to do with the growth rate of great danes) - it is only occassionally that growth rate, by itself, significantly effects wood strength (MOE, modulus of elasticity). To the extent that some species growth rate is positively correlated earlywood/latewood ratio, wood with more earlywood will tend to have less strength. In the case of the oaks, though, fast growth rates tend to increase latewood production and hence increase density and MOE. Furthermore, saplings toppling over does not happen due to growth rate directly, but is more likely related to stem taper - as influenced by spacing and competition for light. If some species or individuals are intense competition for light (possibly species that grew the fastest when planted under a constant, but too small a spacing), they will tend to have less taper and will be less stable under mechanical loading. My overall points are these - 1)Please carefully consider the duration you expect to make your measurements for in order to be best matched with your nutrient, watering and planting regime. 2)Be aware that any of the above could interact to create somewhat artifical species-effects and this could influence the direction and/or the magnitude of the effects on a number of properties through direct or indirect effects. Cheers, Steve Voelker Oregon State University Wood Science & Engineering Forest Science
