Biodiversity outcomes resulting from ecological management in Pūtaringamotu/Riccarton Bush.

Pūtaringamotu/Riccarton Bush is a 7.8-hectare remnant of kahikatea (Dacrycarpus dacrydioides) forest found in the urban centre of Christchurch. The remnant forest was originally mismanaged using an English woodlot approach, this was rectified when an ecological management regime was implemented in the 1970s. This has allowed the indigenous flora and fauna to recover following the initial mismanagement period. The objective of this research was to determine whether fundamental changes have occurred in Pūtaringamotu because of the establishment of proactive management. This was assessed by quantifying the changes in two biodiversity groups; vegetation and avifauna over the last 20 years and 15 years respectively to evaluate whether effective management of the forest has resulted in a significant improvement in biodiversity. The vegetation of Pūtaringamotu was investigated by measuring ten permanent sample plots to assess changes in abundance, composition and diversity using proxies of cover, basal area, and species richness and Shannon’s index respectively. It was found that no significant differences between years occurred over the 20-year period. This indicates that fundamental differences in vegetation are yet to occur in Pūtaringamotu. However, insignificant differences in abundance and composition are present with more plots having increases than decreases for cover and basal area. In juxtaposition, diversity experienced more stabilisation or decreases than increases for species richness and diversity over the 20- year period. This suggests marginal changes are still occurring in Pūtaringamotu. Overall, vegetation in Pūtaringamotu has been maintained as a result of the establishment of proactive management in the remnant. The avifauna of Pūtaringamotu was assessed using five-minute bird counts to see if changes have occurred in abundance, composition, and diversity measured through proxies of total species, indigenous and exotic bird presence, and species richness and Shannon’s index respectively. It was found that no significant differences occurred between years, indicating fundamental changes in avifauna are yet to occur in Pūtaringamotu. Exotic avifauna remain more dominant in Pūtaringamotu than indigenous avifauna with significant differences occurring between the two groups for species richness (ANOVA, F = 36.57, df = 1, P = 0.03) and Shannon’s index (ANOVA, F = 32.42, df = 1, P = 0.03), This suggests that management thus far has not resulted in more heterogeneous avifauna. Overall, the avifauna of Pūtaringamotu have been maintained in the remnant as a result of the establishment of proactive management. It is likely that proactive ecological management in Pūtaringamotu over the last 50 years has had positive effects on maintaining biodiversity values in the remnant. This information will be useful for informing future management protocols utilised for Pūtaringamotu. It is recommended the Riccarton Bush Board of Trustees continue to employ current management interventions as they are effectively maintaining vegetative and avifaunal biodiversity. It is also recommended that further management efforts should focus on addressing the incursion of weeds along the remnant edge by increasing weed control, culling Rock Pigeon which act as a pest within the urban remnant, and facilitating biological recruitment into the forest by artificially introducing new species to the remnant as the isolative nature of the remnant restricts significant sources of biological recruitment