Understory development in young Cordia alliodora plantations

The biomass and composition of theunderstory plant community associated with Cordiaalliodora planted at 2 m × 2 m spacing arecharacterized for the first (1992) and fifth (1996)years after stand establishment. The study plantationscomprise three replicates each of C. alliodoramonocultures and C. alliodora interplanted withperennial monocots (polycultures), part of anexperiment located at the La Selva Biological Stationin northern Costa Rica. In the first year, there wasno significant difference in the mean abovegroundunderstory biomass between the monocultures of C.alliodora (7975 kg/ha) and the polycultures of treesand monocots (5427 kg/ha). After 5 years, theunderstory biomass in the monocultures increased(16,918 kg/ha), while in the polycultures it decreased(116 kg/ha). In contrast to the first year, therefore, by the fifth year the understory biomass differed significantly between the two types of plantations (p = 0.005, R² = 0.78, LSD = 5200 kg).In the first year, 109 plant species were present inthe understory of the C. alliodora monoculturesand polycultures. The dominant species in both themonocultures and polycultures was the monocot Tripogandra serrulata; Panicum polygonatum wasranked second. After 5 years, 20 species representing15 families were present in the monocultures. Thedominant species was Paspalum conjugatum,followed by Tripogandra serrulata. Only two newspecies were recruited, and both were woody shrubs:Nectandra membranacea and Vernonia patens.