Plume Dispersion in Four Pine Thinning Scenarios: Development of a Simple Pheromone Dispersion Model

Abstract

A unique field campaign was conducted in 2004 to examine how changes in stand density may affect dispersion of insect pheromones in forest canopies. Over a 14-day period, 126 tracer tests were performed, and conditions ranged from an unthinned loblolly pine (Pinus taeda) canopy through a series of thinning scenarios with basal areas of 32.1, 23.0, and 16.1 m2ha-1. In this paper, one case study was used to visualize the nature of winds and plume diffusion. Also, a simple empirical model was developed to estimate maximum average concentration as a function of downwind distance, travel time, wind speed, and turbulence statistics at the source location. Predicted concentrations from the model were within a factor of 3 for 82.1 percent and 88.1 percent of the observed concentrations at downwind distances of 5 and 10 m, respectively. In addition, the model was used to generate a field chart to predict optimum spacing in arrays of anti-aggregation pheromone dispensers.