Large Planting Stock Type and Mechanical Release Effects on the Establishment Success of Picea glauca Plantations in Quebec, Canada

Figure 7

Average percent of full sunlight (%PAR) reaching the upper half of large containerized and bareroot Picea glauca seedlings outplanted in south central Quebec (Canada) over eight growing seasons. %PAR was assessed based on the method described by Jobidon [30]. Treatments consisted of four intensities of vegetation management, including a control, mechanical release during the third growing season (REL3), and mechanical release during the fifth growing season (REL5). The fourth treatment (No competition; NC) was not included in the analyses, as by definition it consisted of the complete elimination of any competition for light, using repeated herbicide and mechanical release treatments. Values were therefore 100% under the NC treatment over the entire experimental period.