Ecosystem diversity is to be assessed using the Criteria for the Identification of Significant Ecological Areas in Auckland (Sawyer & Stanley, 2012) published by Auckland Council. Relevant assessment criteria include:
Representativeness - a factor that assesses the types of ecosystems and the species that live in them against Auckland's original ecosystem types
Threat status and rarity - an assessment of the threat of extinction or decline of all levels of biodiversity (genetics, species, communities, habitats and ecosystems) at all scales (site, catchment, region and nationwide)
Diversity - an assessment of the different drivers at different scales including aspects such as competition between species, disturbance history, climatic variables and landform
Uniqueness or distinctiveness - an assessment of whether the environmental resource only occurs in the Auckland region.
Terrestrial habitat diversity
Diversity assessment will consider the regional and catchment significance of site resources. WSD promotes the protection and enhancement of diverse native vegetation types. This may include the following potential land management responses:
Provide a planted riparian buffer to protect existing 'interior' habitat from disturbance and thereby protect unique microclimates and associated habitat diversity
Re-vegetate a site with pioneer vegetation species to develop soils and allow for natural succession processes to occur
Enhance a site by planting complementary flowering and fruiting species to extend food sources for native fauna
Restore multiple vertical vegetation 'tiers' from root zones and litter layers, through herbaceous plants, shrubs, canopy, and emergent trees to form diverse habitat niches (refer to Figure 17).
Plant species diversity
In addition to their natural character and ecosystem values, native plant species have good survivorship and often require less replacement and maintenance than introduced species over the long-term. 'Eco-sourcing' involves the collection of divided plant material or seed from remnant vegetation as close as possible to the location of proposed planting, and ideally from a similar ecotone (a similar environment in terms of climate and elevation). This is a means to protect unique genotypes of plant species, which can also be best suited for the local environment.