Growing a community's sense of 'heritage': a former mataī forest from SW Ōtautahi Christchurch and its nitrogen status, 860-1430 CE.

As in many places, heritage narratives in Ōtautahi Christchurch remain focused on colonial times. To expand these narratives, we examined three subfossil mataī () excavated along a 700 m arc during residential subdivision earthworks. Characterisation used N, radiocarbon, and ring width measurements. Conventional (uncalibrated) radiocarbon ages were 1222 BP (calibrated median 856 CE), 932 BP (1148 CE) and 545 BP (1425 CE). Mean N values of +1.0 ± 1.1‰ (±SD) were similar to nearby alluvial forest remnants, with no discernible change through the 550-year sampling interval. Ring widths in three trees from the 545 BP site were 0.58 ± 0.12 mm, half that of present day mataī from humid West Coast forests at a similar latitude. The 545 BP site included a burnt stump, and stumps with longhorn beetle (Cerambycidae) larval galleries that occur only in already dead trees. We conclude that the forest was slow growing and mesotrophic but dynamic due to periodic flooding, ending with fire around 1430 CE and inundation of the dead standing forest years or decades later. We are now using traditional and social media and artists to disseminate the narrative of a former mataī forest 'beneath our feet' through schools, community groups, and in public facilities.