Evaluation of the Hamilton City Council plants for Gullies programme

This evaluation found that the Hamilton City Council Plants for Gullies programme is successfully facilitating the restoration and enhancement of Hamilton City gullies by private gully owners. The mean number of native species in surveyed gullies was 2.1 in non-restored sites and 18.4 in restored sites. While the mean number of invasive species was 4.1 in non-restored sites to 2.6 in restored sites. This quantitative measure is a valuable indication of the ecosystem gains for Hamilton City. Hamilton gully owners are very satisfied with the Plants for Gullies programme; the mean satisfaction rating was 8.9 out of 10. These residents dedicate significant time and energy to restoring their gully sections; the mean time contribution of survey participants was 10.3 hours per month. Gully owners were found to be utilising knowledge acquired through participation in the programme to add valuable diversity to their gully ecosystems. This was repeatedly demonstrated by programme participants not only reintroducing the native plants supplied by the programme but also adding large quantities of privately-sourced plants. This investigation found that the Plants for Gullies and Gully Restoration programmes are effective in communicating key ecological restoration concepts. This was reflected by gully owner prioritisation of eco-sourcing, biodiversity and weed control as considerations in their restoration projects. The Gully Restoration Guide was found to be the most valuable component of the programme’s educational tools. However, it is recommended that this resource is updated to support the many gully owners who require information for advanced stages of ecological restoration. In summary, the Plants for Gullies programme is successfully delivering gully restoration assistance and advice to gully owners, which is resulting in significant improvements to Hamilton City’s gully systems. The programme is valued by all who are involved and could be recommended to other New Zealand cities as an effective model for environmental restoration and community engagement

Effect of Coriaria arborea on seed banks during primary succession on Mt Tarawera, New Zealand

An experiment was conducted over two years to investigate the effect of Coriaria arborea, a native nitrogen-fixing shrub, on soil seed banks at sites representing a post-volcanic successional sequence on Mt Tarawera, New Zealand. The sites ranged from bare volcanic ash and lapilli substrate, through low-growing pre-Coriaria vegetation, to dense stands of Coriaria scrub. Soils (to a depth of 50 mm) under recently established Coriaria and older stands had more seedlings (1096 and 1585 seedlings 0.4 m-2, respectively) and species (37 and 45 species 0.4 m-2, respectively) emerge than where there was no Coriaria (243-320 seedlings 0.4 m-2, 14-25 species 0.4 m-2) and were the only soils with Coriaria seedlings. In total, 3488 seedlings representing 63 taxa were recorded. Seeds were still germinating after 24 months but rates declined markedly in the second year. For example, Coriaria reached a germination peak at 8 weeks but continued to germinate sporadically over the 2-year period. Tree species present in young forest within 0.5 km of the sites were absent. Establishment of Coriaria greatly accelerated an underlying trend of gradually increasing abundance and diversity of seeds in the soil with vegetation age. Adventive, wind-dispersed, and annual species were over-represented in the seed banks compared with the regional evergreen forest-dominated flora. These proportions are expected to decline as succession to forest gradually occurs