Dry Creek Replacement Cleanfill, SH 58, Porirua - Hutt City Council

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3.0 The Study Area 3.1 History and Site Context The application site is located within the Sounds-Wellington Ecological Region (39) and the Wellington Ecological District (39.01). The Wellington Ecological District is characterised by steep, strongly faulted hills and ranges, and the Wellington and Porirua Harbours. The ecological district is windy with frequent NW gales, warm summers, and mild winters. Rainfall is typically between 900 and 1400 mm p.a. (McEwen, 1987). The Wellington Ecological District was originally forested with fringes of salt marsh vegetation around the harbours. Near the coast rimu-rata/kohekohe forest dominated; podocarp forests (kahikatea, totara, matai) dominated on the river terraces and lower slopes; and miro-rimu/tawa forest dominated at higher altitudes. The Porirua Basin was part of the Wellington beech gap. What little beech was present (black beech and hard beech) was confined to stands which extended over the ridgelines from the extensive beech forests of the Hutt Valley on the eastern fringes of the ecological district. At the application site, a podocarp/broadleaf forest would have dominated, with rimu and northern rata emergent over a tawa dominated canopy (Boffa Miskell, 2001)1. Scattered remnants of this original forest occur some distance to the south and south-east of the site in the vicinity of the Haywards Hill Substation and on the fault escarpment above SH2. The habitat and ecological corridor values of this fault escarpment and associated forest remnants have been identified in Forest & Bird’s 1990 “Natural Wellington” report. Today this ecological district is almost entirely modified by farming and urbanisation, with pasture, plantation pine, gorse and regenerating shrublands throughout. Some small forest remnants occur. At some time during settlement of the Porirua basin all original vegetation within the application site was cleared and converted to pasture. Today the application site is still dominated by improved pasture or a rank pasture mosaic. However, regeneration is occurring in a number of areas, predominantly pioneer scrub and shrublands dominated by manuka, with small areas of regenerating low forest where mahoe and/or kanuka is emergent. A comparison of the 2011 aerial photograph with earlier images from 2005 and earlier illustrate both the lack of older vegetation present and the rapid ecological succession of the main gully system upstream of the application site - from pasture and gorse to scrub and low forest. On the dryer north facing sites kanuka regeneration is more prevalent. Regenerating broadleaved forest dominated by mahoe is more typical on the wetter south facing slopes and in sheltered gullies. The regeneration of secondary native vegetation on the inland hills and basins of the Western Hutt Hills / Belmont Hills and along the adjacent fault escarpment is part of a major landscape transformation that is occurring throughout the Wellington Region. Regenerating scrub and low forest now dominates what were steeper and less productive hillsides which were primarily pasture and gorse-covered 20-30 years ago. A Land Cover Environments of New Zealand (LENZ) analysis of the application site indicates that the vegetated upper slopes of the application area have no threat classification, while the lower areas of improved pasture within the application site are acutely threatened (LENZ Level 4). A LENZ map of the study area is attached as Appendix 3. However, given the close linkages with 1 We note that the Porirua City Council’s inventory of ecological sites used a unique analysis tool for assessing significance. Because so little original indigenous vegetation remains within the District, the value of the shrublands and scrub habitat and refugia present is elevated. Dry Creek Replacement Cleanfill, SH 58, Porirua | Assessment of Terrestrial Ecological Effects 6
the adjacent Belmont Regional Park, the regenerating vegetation present has a number of ecological habitat and corridor values. 3.2 Land Use and Statutory Context All the land that is the subject of this application is owned by Malcolm Judd and is zoned ‘Rural’ in the Porirua City District Plan. The surrounding land to the north, west, south and east is also zoned Rural and comprises similar steep farmland with gullies largely dominated by regenerating indigenous vegetation. There are a number of scattered lifestyle blocks and houses situated to the east, some 350 – 600 m distant. Many of these adjacent lifestyle blocks are similarly vegetated with a mix of pasture and regenerating indigenous vegetation, particularly within the steeper gully systems. Further to the south of the application site, beyond an adjacent property also owned by the Judd Family, is the Belmont Regional Park. Vegetation Clearance Rules The Porirua City District Plan limits clearance of vegetation in association with permitted activities in the Rural Zone. Removal of native vegetation is not permitted where: a) The area of vegetation exceeds 1 hectare with an average height of 3 metres of more, or b) The area of native vegetation is part of an area in one or more sites, which exceeds 1 hectare with an average height of 3 metres or more (Rural Zone Permitted Activity Standard D4.2.1). As part of the vegetation mapping undertaken, we have attempted to delineate areas and types of vegetation with an average height of 3 m (refer Figure 2). The vegetation removal associated with the original cleanfill proposal would have required the removal of approximately 13.4 ha of indigenous vegetation with an average height of 3 metres of more. The revised proposal which is assessed here will require the removal of approximately 0.7 ha of vegetation with an average height of 3 m or more from within a much larger gully system of regenerating indigenous vegetation as well as a number of smaller, separate areas of regenerating indigenous vegetation. Significant Natural Areas Survey Areas of regenerating shrubland similar to those within the application site occur in a number of locations within the Porirua Basin. In the Porirua City Council’s ‘Inventory of Ecological Sites in Porirua City’, large areas of manuka scrub in ‘unused reverting bush areas’ to the south and west of the application site were identified as being ecologically significant. These sites are listed as Eco sites PCC 217a and PCC 217d and consist of 45.153 ha of manuka scrub located in upper Harris Road. They are ranked as SES4 and considered to be ‘highly ecologically significant, but not rare or scarce in Porirua City’. There are 44 sites within the district that have an SES4 ranking. The regenerating vegetation within the application site is not listed within the ecological sites inventory. Dry Creek Replacement Cleanfill, SH 58, Porirua | Assessment of Terrestrial Ecological Effects 7
Page 1 and 2: Dry Creek Replacement Cleanfill, SH
Page 3 and 4: CONTENTS 1.0 Introduction 3 2.0 Met
Page 5 and 6: 1.0 Introduction Boffa Miskell has
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Page 11 and 12: MAIN HABITATS and FEATURES AREA (ha
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Page 15 and 16: Statement which provides an interim
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Page 19 and 20: combined have an area of 0.7 ha. Th
Page 21 and 22: terrestrial mitigation sites. Consi
Page 23 and 24: 9.0 References Boffa Miskell. 1998:
Page 25 and 26: Asplenium hookerianum Asplenium pol
Page 27 and 28: Appendix 2 Site Photos Dry Creek Re
Page 29: Photo 7: Looking downstream of main

Dry Creek Replacement Cleanfill, SH 58, Porirua - Hutt City Council

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