Photosynthetically Active Radiation in the Clearcut Site at Harvard Forest since 2013

The purpose of these measurements was to capture the light attenuation of the canopy throughout the growing season, which can help in determining leaf area/canopy openness at the site. Measurements were done along a 50-m-long transect (one of the ones used for line-intercept vegetation surveys, on the side of the EC-tower). Eight measurement locations were established along the transect, equidistant, and marked with a bright orange flag. Measurements were taken with a LI-COR LI-191 Line quantum sensor (http://www.licor.com/env/products/light/quantum_sensors/), as described below. Before and after measurements along the transect, PAR-readings were taken in an open area (away from canopy cover) either at a log along the access road to the site or up on the fire tower nearby. At each location along the transect, two measurements were taken – one at the ground surface and one at a height of 1.3m (diameter at breast height).