EMROP: Waihi North Project WAI-985-000-PLN-LC-0001_Rev0 clean 2.5 MODELLED OFFSETTING ACTIONS It is proposed that a minimum of 16.5 ha of offset planting and 20 ha of offset enhancement planting (via pine removal and replacement with future native canopy trees) is to be undertaken to offset the loss of protected terrestrial ecological values with respect to the TSF incursion into SNA 166. The 16.5 ha of offset planting is proposed to be undertaken within and adjacent to the existing southern SNA 166 fragment. Particular focus of offset revegetation is to: 1. Improve connectivity between the northern and southern fragments of SNA 166; 2. Provide enrichment species that will ensure succession to a future WF11 forest type which will have historically occurred there; 3. Target habitat-specific revegetation (e.g. vineland, flaxland) around known habitat for moko skink (Oligosoma moco) a Nationally ‘At Risk’ species, with densely growing and fruit producing ground cover vegetation that will facilitate population growth and expansion beyond existing, isolated areas. The species composition for the proposed restoration planting is based on the kauri, podocarp, broadleaved forest ecosystem type (WF11, Singers & Rogers 2014) and includes 31 species, including a minimum of 15 canopy species and 25 understorey species (Table 11, Table 12). All planting undertaken for the WNP (including 18.7 ha of area for replacement planting, 16.5 ha offset planting and 20 ha enhancement planting) will have legal protection in perpetuity (via covenant or similar), pest and weed control. PROPOSED OFFSETTING The BOAM for offsetting SNA loss (Table 3, Table 4) demonstrates that 16.5 ha of revegetation for the loss of 8.3 ha of SNA scrub will deliver biodiversity gains in 20 years with a high level of confidence (>90%). A further 20 ha of pine tree removal within SNA 166 and replacement with future WF11 forest canopy trees for the loss of a 1.2 ha fragment of ‘not protected’, naturally occurring pōhutukawa / rewarewa vegetation will deliver biodiversity gains in 20 years with confidence (75-90%). The lower level of confidence in enhancement actions (compared to >90%), despite the much larger area over which enhancement actions will be undertaken, is due in part to the habitat value that pine trees may already provide to fauna. Therefore, their initial removal will reduce the ecological uplift (amount gained by improving existing values) that could otherwise be achieved by planting an area where biodiversity attributes are nearer to zero. However, it is important to note that, while enhancement measures may not provide as much ecological uplift within the 20-year timeframe to measure the offset outcome, pine trees will continue to gradually spread throughout the SNA, beyond this time if not properly managed. The Department of Conservation estimates that wildling pines spread at an estimated rate of 5% per year, where they outcompete native vegetation and reduce habitat resources for indigenous wildlife (and hence reduce biodiversity). Therefore, it is expected that the large existing areas of pine-dominant vegetation within the southern SNA 166 fragment will require ongoing management to prevent this spread, if not
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