Longevity and Diversity – design

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STAND LONGEVITY AND LIFE-FORM DIVERSITY AS CONTROLS OF ECOSYSTEM FUNCTIONING

The main plots of the Huertos experiment contained two axes. One axis was stand-longevity, in which tree monocultures were cut and replanted annually, at four-year intervals, or left uncut. The other axis was a life-form diversity gradient, comparing uncut tree monocultures with polycultures containing plants of three life forms. The life forms consisted of a canopy tree species plus a palm (Euterpe oleracea) and a giant, perennial herb (Heliconia imbricata). Life forms were chosen on the basis of their relative contribution to the proven, evolutionarily successful local flora.

To reduce the likelihood of an idiosyncratic effect due to choice of tree species, the experiment was repeated with each of three tree species: Hieronyma alchorneoides (Phyllanthaceae), Cedrela odorata (Meliaceae), and Cordia alliodora (Boraginaceae). Those native tree species differ in architecture, phenology, and physiology, but all of them thrive on the nutrient-rich volcanic alluvium at the study site.

Three tree species x four treatments x three replications = 36 plots, which together with various ancillary treatments occupied about 8 hectares.