Growth of five species of trees on experimental plots on sand tailings left after mining for rutile in Sierra Leone

Data consists of the height of five species of trees after 2.5 years of growth; the five species are:
? Gmelina (Gmelina arborea),
? mango (Mangifera indica),
? cashew (Anacardium occidentale),
? citrus (Citrus sinensis) and
? monkey apple (Anisophyllea laurina).
Trees were planted on the sand tailings which consit of a very coarse quartz sand (silts and clays are dumped separetly during the processing of the rutile in the ?wet plant?). The lack of