Luquillo LTER

Ranked variables (Rock Cover, Litter Cover, Dead Wood Cover, Vine Cover) assume one of five states depending on the relative amount of cover (1 = 0-20%, 2 = 21-40%, 3 = 41-60%, 4 = 61-80%, 5 = 81-100%). Canopy openness was evaluated using a spherical densiometer positioned 0.5 m away from the point in each of the cardinal directions. The average of these four readings can be considered a description of canopy openness. A nail was driven into the forest floor 1 m from the point in each of the cardinal directions, the number of leaves obtained thus is used as an estimate of litter cover. Plant apparency (Cook and Stubbendieck 1986) for common species was also recorded. The number of foliar intercepts, defined as a species-specific count of vegetation touching a wooden dowel, was counted at each of 7 heights (0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 m) using a plant apparency device (Cary 1992, Secrest 1995). Four 0.5-m dowels were positioned at 90-degree angles at each height. The device was positioned 1.5 m from the central point in each cardinal direction, and the number of intercepts recorded. Blank cells in the data files indicate missing values or variables that were not measured during a sampling period.