The main research objectives of the Douglas fir chronosequence sites have been to study the mechanisms of CO2 exchange in Canada’s most productive forest zone, and determine the effect of forest management practices and harvesting on C sequestration and loss. The coastal forest site near Buckley Bay, BC is the only remaining active site of a larger Douglas-fir chronosequence dataset on Vancouver Island, consisting of multi-year datasets measured by UBC tower platforms above clearcut harvested stands (HDF00, HDF11), an intermediate-aged stand from when it was 49 years old until it was harvested at 62 years old (DF49) and the current early-age stand at Buckley Bay (HDF88).
All sites have contributed data between since 1998. At HDF88, a 21 m EC-tower is located in a forest that was planted in 1988 with a stand density of 1240 stems ha-1. EC-flux and climate measurements at this site have continued uninterrupted since 2001 with support from Timber West and Island Timberlands. In collaboration with forest industry partners, in an NSERC Strategic Research Grant project, the stand was fertilized with urea at 200 kg N per ha-1 in January 2007. Fertilization resulted in a remarkable increase in forest productivity (150-300 g C m-2 y-1), which
has continued through 2012. The data from HDF88 have been used in national and international C flux syntheses (including those sponsored by the North American Carbon Program) and resulted in 91 peer-reviewed publications to date. It has also been used in the testing and
calibration of forest C balance models including CCLASS, ecosys, EASS and CBM-CFS3. The latter model is being used to assess forest C credits associated with different management scenarios. Industry foresters and modelers would like to see the gap in medium-aged flux data filled in order to have reliable totals of C sequestration over the entire lifetime of a stand (Coursolle et al., 2012).
In January 2011, a 77 ha section of forest surrounding the DF49 flux-tower was commercialy harvested. The clearcut that resulted was replanted in April 2011 and the site was renamed from DF49 to HDF11. Carbon, water and energy flux-measurements were continued from a smaller scaffold tower; the analysis of those data provided a unique opportunity to assess the space-for-time approach employed in chonosequence flux-tower studies (Paul-Limoges, 2013: M.Sc thesis).
