(1992-1996). Abstract approved: AN ABSTRACT OF THE THESIS OF Susan Stevens Hunimel for the degree of Doctor of Philosophy in Forest Resources presented on June 6. 1997. Title: Stand Development of Cordia alliodora (Boraginaceae). a Neotropical Secondary F

Cordia alliodora is used for reforestation programs and farm income in northern Costa Rica. This study investigated: 1) responses of C. alliodora associated with stand density, or trees/ha (TPH), and 2) plant diversity and biomass in the understory of C. alliodora plantations. Three Nelder plots, 31 temporary plots and 6 plantations in northern Costa Rica were measured between 1992-1996. The plots included monocultures of C. alliodora (MONO) as well as polycultures of C. alliodora (POLY) planted with crops, pasture or other trees. Plot measurements included: tree height (HT), age (AGE), breast height diameter (DBH), height-to-crown (HToCR), and crown diameter (CD), site soil texture and pH. Understory measurements included the number of total plant species (SR) and aboveground biomass (UBIO). The HT of C. alliodora was related to AGE and DBH, but not to TPH. DBH was directly related to AGE and CD, and decreased with increasing TPH. The HToCR and volume/ha of C. alliodora were significantly associated with TPH, AGE and whether the plot was a MONO or POLY. The ratio of CD/DBH wa