Rotoehu Forest
Rotoehu Forest is 8875 hectares of production forestry between 1 and 4 harvest rotations managed by Timberlands Ltd. Lynda had been providing advice about archaeological sites at Rotoehu Forest since the days when it was under NZ Forest Service management, and had subsequently been engaged by Timberlands to help manage archaeological sites in a few forest compartments that were due for harvest.
At the time, there were 40 archaeological sites recorded across the 116 compartments. The surrounding landscape beyond the forest boundary has a dense distribution of archaeological sites. For many years Rotoehu Forest had been identified by archaeologists as a potential survey ‘gap’ and, as harvesting activity increased in the forest, it became clear that there were in fact many unrecorded sites present. In addition, most of the recorded sites had not been accurately located and it was vital to improve the quality of data prior to harvest activity so that accidental damage could be avoided.
Timberlands were keen to trial an initial desk-based approach to archaeological fieldwork and were able to give us access to recently captured LiDAR data.
We ‘removed’ the tree canopy from the LiDAR data to enable visibility of any recorded or potentially unrecorded archaeological sites. We then looked for indications of the previously recorded sites, updating the location and site extent if it was inaccurate. The results were field tested by targeted survey to identify and record potential archaeological features seen on the LiDAR.
LiDAR imagery showing the forest with canopy cover (left) and with the LiDAR data cleaned to remove canopy cover, revealing archaeological features (right). Both images were made prior to harvest.
During the desk-based inspection of the LiDAR we identified 191 areas of interest. To date, 69 of these have been confirmed as archaeological sites during subsequent fieldwork and have been entered into ArchSite and the Timberlands GIS.
Overall, 56 of the 116 forestry compartments contained recorded archaeological sites or areas of interest. 60 compartments had no recorded sites or areas of potential sites. This information greatly assists with harvest planning and gives Timberlands, tangata whenua and Heritage New Zealand confidence that archaeological sites are being appropriately managed and cared for throughout the production cycle. LiDAR prospection followed by targeted field survey is a time and cost-effective archaeological site management tool for Timberlands Ltd.