Save Happy Valley!

Resource Consent Submission

Philip Knightbridge :: Department of Conservation

1. My name is Philip Ian Knightbridge. I am employed as a botanist by the Department of Conservation, West Coast Conservancy. I have been employed as a researcher on pest impacts by Landcare Research between 1994 and 1998, and as a botanist by the Department of Conservation between 1998 and the present. I hold a BSc in Botany/Zoology and an MSc in Botany/Environmental Science.

2. The evidence I present today will confirm the vegetation and flora values present at the proposed mine site, the context of these values in a regional and national setting, the potential adverse effects the proposed mine would have on these values, and whether these effects can be avoided, remedied or mitigated. I have visited the proposed mine site on three occasions: 26 November 1998, 21 August 2003 and 13-14 January 2004. The most recent visit traversed the upper Waimangaroa Valley from Happy Valley south to Cedar Stream and included the proposed Cypress mine site.

Vegetation and Flora of the Proposed Site

3. The natural values, particularly the vegetation and flora, of the proposed Cypress mine site have been very well described in various reports prepared for Solid Energy as part of the Cypress mine proposal (e.g. Bartlett 2003; Glenny 2003), and in the Department of Conservation’s survey report for the Protected Natural Areas Programme (PNAP) for the Ngakawau Ecological District (ED) (hereafter referred to as the Ngakawau PNAP survey) (Overmars et al 1998).

4. Given that these values have been so well described, and there is general agreement on what these values are, rather than repeating the details of these reports I will provide a brief summary of the applicability of the Department of Conservation’s PNAP survey findings, confirm in my view that the vegetation is significant in terms of section 6c of the Resource Management Act, and highlight any areas where my opinion differs from that of Solid Energy’s application.

Significance of vegetation and flora of the proposed Cypress mine site within the Ngakawau Ecological District

5. In 1987 the Department of Conservation initiated the Ngakawau PNAP survey with the objective of defining the conservation values of the Buller coal plateaux and recommending areas for protection (RAPs) to protect a representative range of the elevated shrub-tussockland ecosystems found on Brunner coal measures. This was a priority as much of the Buller coal plateaux have already been modified by mining, roading and other activities associated with coal exploration and mining and further mining was likely.

6. The Department had sought to identify RAPs that did not overlap with identified coal deposits. This was possible for some RAPs. However it proved impossible to identify RAPs that avoided identified coal deposits as the areas with the highest conservation values on the coal plateaux tend to be those areas that have not previously exploited for coal.

7. RAP 1, extending from the Upper Waimangaroa Valley south to Mt William, was identified as the RAP containing the greatest ecological diversity in the least modified condition of any of the RAPs identified in the Ngakawau PNAP report. Much of the footprint of the proposed Cypress mine lies within this RAP.

8. The particular features noted within this RAP which are relevant to the proposed Cypress mine are:

  • Upper Stockton plateau pavement vegetation (including those dominated by the coal measures tussock Chionochloa juncea, a species restricted to the Buller coal plateaux);
  • Happy Valley red tussockland;
  • Type locality of the nationally endangered endemic snail Powelliphanta ‘patrickensis'
  • No alternatives for the protection of these features could be identified.

9. For the purposes of this hearing I believe it is most appropriate to concentrate on the potential impacts of the proposed Cypress mine rather than where any protected area boundary might finally end up. A major reason for this is that the proposed Cypress mine site clearly does have high ecological values, which is why it was part of RAP 1 in the Ngakawau PNAP report. This resource consent process provides the opportunity for Solid Energy and submitters such as the Department of Conservation to present their views on whether these significant natural values can be sustained in the long term if an opencast coal mine is approved.

10. Returning to the vegetation features identified in the Ngakawau PNAP report as being of particular note in the proposed Upper Waimangaroa – Mt William RAP, the red tussocklands of Happy Valley are the vegetation feature at greatest risk from the proposed Cypress mine.

11. The red tussocklands of Happy Valley have been identified in the Ngakawau PNAP report as being the best and most diverse examples of red tussockland in the Ngakawau Ecological District. This finding has been confirmed in subsequent surveys (e.g. Kingett Mitchell 1998) which compared the vegetation of Happy Valley with other areas including the Blackburn pakihi and an area of red tussockland adjacent to Webb Stream (downstream of the proposed Cypress mine).

12. The AEE confirms that the red tussock vegetation associations are those that will be impacted most by the proposed Cypress mine in terms of their representation. In particular, the AEE notes that 41% of the dense red tussockland within the Ngakawau Ecological District will be removed during the operation of the proposed Cypress mine (Table 6.8 AEE ).

13. I believe this figure of 41% underestimates the amount of red tussockland that will be removed. The two main areas of red tussockland identified on the vegetation map presented in the AEE are at Happy Valley and Webb Stream. Comparison of oblique photos of the two areas confirm that Happy Valley is indeed dominated by dense red tussockland, whereas Webb Stream is a matrix of red tussock patches and manuka scrub. (Exhibit 1). Based on this, I would suggest that the amount of dense red tussockland within the Ngakawau Ecological District that will be removed by the proposed Cypress mine is closer to 70%.

14. Furthermore there is evidence that manuka is becoming increasingly dominant in the Webb Stream area at the expense of red tussock. This is a natural process that reflects past disturbance history at this site. In contrast it appears that dense red tussockland will remain the dominant vegetation type of Happy Valley well into the foreseeable future. A combination of the current cold air drainage and ponding patterns in association with impeded drainage, and movement of groundwater from east to west from slopes of Mt William range appears to favour red tussock at the expense of woody species. The death of many manuka in Happy Valley following the unusually cold winter of 2001 supports this interpretation. (Exhibit 2). Thus the statement by Williams (2003) that much of the present red tussockland in the Upper Waimangaroa is being invaded by manuka applies to Webb Stream but does not appear to apply to Happy Valley.

15. Finally, there is an identified coal resource beneath the red tussockland – manuka scrub present at Webb Stream. Thus, even if this area were dense red tussockland, in the near future it too could be subject to a coal mining proposal.

16. The Upper Stockton plateau pavement vegetation was the other vegetation feature of particular significance within the Ngakawau PNA report’s RAP 1. This vegetation type will be well protected even if the proposed Cypress mine proceeds as the majority of the unmodified areas lie outside of identified coal resources. The major exception to this is the pavement on Mt William south.

17. The proposed Cypress mine overburden area will destroy an area of about 65 ha of pavement vegetation. It is agreed that of the four possible options identified in the AEE for the disposal of this overburden this option will have the least overall impact on the vegetation. If the mine does proceed, the only preferable option from a vegetation point of view would be reducing the size of the overburden landform by using more of the overburden at the southern end of the mine to recreate a landform closer to the original landform, and to dispose of more of the overburden at the existing Stockton mine. I recognise that there are likely to be numerous engineering and economic constraints to these options.

National significance of vegetation and flora of the proposed Cypress mine site

18. So far I have confined the discussion of the significance of the vegetation of the proposed Cypress mine site to within the Ngakawau Ecological District. I will now expand on this to discuss national significance.

19. Following the preparation of a draft Ngakawau PNAP report in 1992, Coalcorp (Solid Energy’s predecessor) suggested that there may be alternatives for protection of coal measure vegetation types and landscapes outside the Ngakawau Ecological District. In response to this the Department of Conservation undertook a detailed assessment of Brunner and Paparoa coal measures outside the Buller coal plateaux (Appendix IX in Overmars et al 1998).

20. Seventeen sites containing Brunner coal measures were identified. The assessment concluded that the Buller coal plateaux contain by far the largest occurrence of Brunner coal measures in New Zealand, with the greatest diversity of vegetation types on coal measures, and could thus be recognised as a nationally outstanding landscape in its entirety. In fact the Ngakawau Ecological District is the only ecological district in New Zealand defined by the presence of extensive elevated coal measures rocks and associated landforms and vegetation (McEwen 1987).

21. The most comparable area to the Buller coal plateaux is the gently tilted Mt Davy plateau at the southern end of the Paparoa Range. However, Mt Davy is much smaller and lacks the diversity of vegetation found on the Buller coal plateaux. For these reasons although it too has high natural values, it was not considered a suitable alternative to protection of the landscapes and vegetation types of the Buller coal plateaux.

22. Other areas with apparently similar vegetation associations can be found on poorly drained siliceous rocks such as the peneplains of the Gouland, Gunner and Mackay Downs to the north. The red tussockland associations of Happy Valley have their closest counterparts here. The major difference between the red tussocklands of the Ngakawau Ecological District and those to the north are the location of the former at a lower altitude and the resultant differences in species assemblages.

23. Following the classification adopted in a soon to be published guide to wetland types in New Zealand, the red tussocklands are classed as a type of wetland called a fen (Johnson & Gerbeaux in press). Fens are peatlands receiving inputs of groundwater and nutrients from adjacent mineral soils and the water table is typically near the surface. They are less acid and slightly more fertile than bogs. Red tussock is a typical species of fens in New Zealand. The fact that these red tussocklands are a wetland further confirms their significance. Nationally it is estimated that about 85% of New Zealand’s wetlands have been lost in the last century (Ministry for the Environment 1997).

24. No nationally threatened vascular plant species are known to occur within the proposed Cypress mine site. Thirteen herb and shrub species were identified in the Ngakawau PNAP report as only being found within the Ngakawau Ecological District in a series of wetlands along the western margins of Happy Valley. All but two of these species have been confirmed as occurring outside the proposed Cypress mine footprint. Their presence has been a major reason for the development of a ‘Red Tussock Wetland Boundary Management Plan’ which aims to protect especially valuable and vulnerable areas close to the footprint of the proposed mine. None of these species are nationally threatened. The small sedge Carex carsei which is ranked as data deficient in the Department of Conservation’s latest threat classification (Hitchmough 2002) (i.e. there is currently insufficient information to give it a threat ranking) is found in bogs along the margin of Cypress Stream. The coal measures tussock Chionochloa juncea and the small herb Euphrasia wettsteiniana are both ranked as range restricted, but both are well represented outside the proposed Cypress mine footprint.

25. A number of significant bryophyte (moss or liverwort) species and one significant lichen species have been identified within the proposed Cypress mine footprint in both terrestrial and aquatic habitats (Glenny 2003; Suren & Glenny 2003). My understanding from the AEE, and the discussion in the Buller District Council staff report on effects of the proposed Cypress mine on biodiversity , is that all but one of these species have also been found outside the proposed Cypress mine footprint. As relatively little is known about bryophytes in comparison to vascular plants it is difficult to place these finds in the context of rarity. It may be that many of these species are rarely collected rather than being truly rare and thus potentially threatened with extinction. However, Glenny (2003) notes that some of these species are likely to be rare because they are confined to areas of high rainfall, infertile soils and the resultant low vegetation. Also, forests dominated by yellow-silver, silver and pink pine and favoured by these bryophytes are no longer abundant in New Zealand.

26. The rich diversity of aquatic bryophytes, including some rarely collected species, was linked to the range of stream pHs in this area (Suren & Glenny 2003). The reasons for the very high aquatic bryophyte cover are not well understood (Suren & Glenny 2003), but it is clear that the streams in the Upper Waimangaroa catchment are ideal habitat for aquatic bryophytes.

27. So what we can be sure about is that the Buller coal plateaux are a significant area for bryophytes with a very high diversity of species present, including a number of taxonomically isolated species. Four habitat types stand out as bryophyte habitat: the red tussockland, stream beds with a bedrock bottom without granitic gravel, forests and forest patches (especially those with yellow-silver, silver and pink pine present) and streams in ditches about 1m deep.

28. Thus, based on the above evidence which has identified that:

  • The Buller coal plateaux contain by far the largest occurrence of Brunner coal measures in New Zealand, with the greatest diversity of vegetation types on coal measures;
  • The Upper Waimangaroa – Mt William RAP as proposed in the Ngakawau PNAP report contains the greatest ecological diversity in the least modified condition of any of the RAPs identified in the Ngakawau PNAP report;
  • By far the best example of red tussockland within the Ngakawau Ecological District occurs within Happy Valley and much of this area, which is a wetland, will be removed during the operation of the proposed mine;
  • The area in the vicinity of the proposed Cypress mine contains a very high diversity of bryophyte species including a high density of what are currently regarded as rare bryophyte species;
  • It seems clear that the vegetation and flora should be considered significant in terms of section 6c of the Resource Management Act 1991. In reaching this conclusion, I concur with the assessment by Dr. Peter Williams for Solid Energy. I have not prepared detailed evidence confirming that the significance criteria from the Buller District Plan are triggered by the vegetation of the proposed Cypress mine. I have summarised this in a Table appended to this evidence if it is required for further confirmation.

29. While I am not a landscape expert, I would note that the Ngakawau Ecological District is the only ecological district in New Zealand defined by the presence of extensive elevated coal measures rocks and associated landforms and vegetation (McEwen 1987), and that the Upper Waimangaroa Valley comprises the least modified remaining area of these coal measures. Accordingly, the unmodified parts of the Upper Waimangaroa Valley, including the proposed Cypress mine site, could be regarded as a nationally outstanding natural landscape.

Effects and Proposed Measures to Avoid, Remedy or Mitigate

30. The proposed mine will have the following impacts on vegetation, flora and natural landscape:

  • Removal of at least 182ha of forest, scrub, red tussockland and coal measures vegetation from what is presently a highly natural vegetation sequence, including removal of 14.5 ha of dense red tussockland within Happy Valley which is widely acknowledged as the best and most diverse example of this association in the Ngakawau Ecological District.
  • Alterations to current landscape, and thus to topography, hydrology, and cold air drainage patterns and subsequent effects on what is presently a highly natural, extensive and complex vegetation pattern.
  • Alterations to hydrology and stream pH which could lead to changes in aquatic bryophyte community composition.
  • Increased potential for weed invasion, particularly gorse and weedy rushes, especially the heath rush Juncus squarrosus, and the effects of this species particularly in low statured vegetation both within and adjacent to the mine footprint.
  • Increased risk of fire and subsequent effects on biota and landscape.
  • Reduction in connectivity of natural habitats in Upper Waimangaroa Valley and thus effects on the movement of propagules and organisms across the valley.

31. In the following section I will consider whether the proposed measures to avoid, remedy or mitigate these impacts are appropriate and whether they are likely to succeed. Most of this discussion centres on the proposed rehabilitation as this is the key remedy proposed for the damage that will be caused to what is currently a highly natural landscape and vegetation sequence.

Rehabilitation

32. The desired long-term outcome described in the rehabilitation plan for the proposed Cypress mine site (Simcock 2003) is that the site will sustain vegetation communities similar to those present before mining. If this outcome can be achieved, the long-term impact of the mine will be substantially reduced. If it cannot the long-term impact will be significant.

33. Based on my knowledge of rehabilitation of mine sites from visits to Stockton, Giles Creek, Larry’s Creek and Island Block, I agree that the proposed Cypress mine rehabilitation plan incorporates current best practice. The basic aim of facilitating natural successional processes by creating stable landforms and substrates which can sustain similar vegetation communities to those present before mining is sensible as it allows nature to create the final vegetation patterns depending on factors such as highly local variation in drainage and topography.

34. It has to be acknowledged that even in the absence of human-induced disturbances vegetation patterns are not static. Natural disturbances such as earth movements or fires ignited by lightning strike can markedly alter vegetation patterns. The complex pattern observed today on the Buller coal plateaux has developed in response to this natural and human-induced disturbance history.

35. Williams (2003) goes so far as to suggest that in some ways the disturbance created by the mine is similar to natural large-scale tectonic disturbance. Whilst this is true to some extent there are some major differences that could alter the final mix of vegetation at the disturbed site. An earthquake is very unlikely to result in the sort of vegetation removal that will occur in the flatter parts of the site such as Happy Valley if the proposed mine is approved. Natural successional processes are able to start immediately after earthquakes in freshly exposed soils, not have to wait for a number of years for mining to cease and begin in soils that have been in ‘storage’ for a number of years. Ongoing human activity at mine sites continues to have the potential to introduce weeds that may not disperse there naturally.

36. This rehabilitation of natural vegetation cover and blending of the constructed landforms into the adjacent undisturbed landscape will take many years. In my opinion it will take about 50 years for a shrubland vegetative cover of 3-5 m height to develop. Within 100 - 150 years species such as mountain beech could be expected to reach 80% of stand top height, which is probably around 12m tall in this area (e.g. fig 10.4 in Wardle 1984). A similar forest structure to that present today, such as with red beech trees in excess of 1 metre diameter and 30 – 40 centimetre diameter pink pine with their associated special bryophyte flora will take in excess of 300 years to develop (e.g. based on growth ring counts of pink pine at Te Kuha, (Department of Conservation 2002)).

37. There are six rehabilitation principles listed in the ‘Rehabilitation Management Plan’:

  • Avoiding disturbance outside the mine footprint
  • Salvage and conservation of soils, vegetation, wood, and invertebrates
  • Constructing landforms that include valley, terrace and hill features i.e. mimic the landform variation currently present
  • Rough surfaces for creating microsites, and favourable depth and quality of substrates on rehabilitation areas
  • Use of local native plant species and locally sourced genetic material, and management of weeds to prevent their establishment and seeding.
  • Best practice stripping, stockpiling and revegetation with continual improvement directed by monitoring results.

All of these are desirable, and if they can be achieved, will certainly assist the rehabilitation of native vegetation. I also agree that fertiliser should be used to speed up initial growth and establishment. Growth rates of species such as red tussock and red beech are very likely to respond positively to fertiliser (e.g. Norton et al 2003). The highest priority for rehabilitation is to establish cover of native species to restrict opportunities for weeds to establish.

38. However, despite the intention to use best practice for mine rehabilitation in my opinion there are some major constraints to the rehabilitation successfully achieving the long-term outcome. These are:

  • The potential for weed invasion, particularly Juncus squarrosus, of bare surfaces exposed by mining
  • The sequence of mine development is such that the best possible use cannot be made of the existing vegetation for rehabilitation purposes
  • The differences between the current and post mining landforms

I will deal with each of these in turn.

Potential for weed invasion

39. Gorse and broom have been identified as the woody weeds of concern. Gorse is the greater risk as it is present in the near vicinity. For example a few gorse bushes grow within the proposed mine footprint area on the proposed overburden dump site in association with a black backed gull colony where they are benefiting from the increased fertility provided by the gull colony. Gorse is also present to the north of the mine site along access roads, and at the abandoned Mitchells mine site to the south. Broom is present around Millerton to the north.

40. I believe that with active gorse control, especially a vigilant surveillance work programme that removes gorse bushes before they produce seed, gorse will be manageable and will not pose a threat to the long-term rehabilitation outcome. This task will be made easier if ongoing gorse control by both Solid Energy and the Department of Conservation on the Buller Coal Plateaux continues to reduce the size of the gorse seed source on the coal plateaux.

41. The adventive heath rush Juncus squarrosus is a more difficult proposition. This European species grows best on acidic, boggy sites. Thus it has been a very successful coloniser of disturbed areas on the Buller coal plateaux, such as on overburden dumps at the Stockton mine. The site visit in January 2004 found that it has also spread along the margins of waterways such as Whirlwind Stream and the Waimangaroa River. Seed has presumably travelled downstream from mining activity in the vicinity of Mt Frederick. Most disturbingly, one plant was found within the proposed Cypress mine footprint in the dense red tussockland of Happy Valley during the January 2004 site visit. (Exhibit 3).

42. The suggestion on pg 275 of the AEE that the species will become a relatively unimportant component of the vegetation at the site is not consistent with its demonstrated invasive nature in other parts of the country such as Marlborough and Southland. The implications of the find in Happy Valley are that this species will persist within dense red tussockland. The only way to prevent this occurring is to prevent seed dispersing to these areas. This is going to be very difficult to achieve given the species is already present in a number of waterways in the area, it produces numerous tiny seeds, and the disturbance associated with opencast coal mining will create ideal habitat for the species to colonise.

43. Evidence from other sites in New Zealand, such as Tarndale in Marlborough, where Juncus squarrosus occurs is that it has the potential to actively invade and dominate bogs with low statured vegetation. (Exhibit 4). Thus I believe Table 7.10 in the AEE understates weed risk by suggesting the displacement of native species by weeds is of minor consequence and that the likelihood is unlikely. I would suggest that for Juncus squarrosus at least, the consequence is moderate to high, and the likelihood is possible (unless the proposed weed control is extremely effective). Similarly, in Table 7.14, the consequence of Juncus squarrosus weed infestation is noted as minor, but would be more realistically estimated as moderate.

44. It is reasonable to ask that given Juncus squarrosus is already present within Happy Valley, will it continue to invade the area even in the absence of opencast coal mining? I believe it is likely that Juncus squarrosus will continue to increase in abundance along stream margins throughout the area, and from here may invade some of the seepages such as those near Cypress Stream shown in Exhibit 4. It is also likely to slowly increase in abundance within the dense red tussocklands of Happy Valley itself, but is never likely to become dominant here other than within low growing patches of herbs. So in the absence of mining and weed control, Juncus squarrosus will probably become sparsely distributed throughout open vegetation in the area, but if mining proceeds there is the potential for it to dominate much of the area proposed for rehabilitation to red tussockland.

45. Williams (2003) suggested that there is nothing that can be done about weedy Juncus species that would warrant spending money. This may well be the case for species such as Juncus bulbosus and Juncus canadensis which are widespread and are probably already occupying most of their potential habitat. However, I do not believe this is the case for Juncus squarrosus, particularly given its potential to invade some of the high value wetlands close to the western margin of the mine footprint.

46. Further discussion with Solid Energy during pre-hearing meetings has confirmed that Juncus squarrosus will be targeted in the weed control programme. The Department of Conservation has funded some experimental work at Tarndale on controlling local infestations of Juncus squarrosus, where it grows in association with another troublesome wetland weed, Carex ovalis. Roundup G2 (glyphosphate) was used and appeared to be successful (Champion1999). Thus it is possible to control Juncus squarrosus, but it will be an ongoing requirement, and one of the most difficult to achieve given the dispersal ability of Juncus seed and the size of the area that control will be undertaken over.

47. A potential major source of Juncus squarrosus seed is the proposal to hydroseed moss sourced from Stockton on high batters in the proposed Cypress mine. Prior to this method being used trials would need to be done to confirm that Juncus squarrosus seed is not present. If it is an alternative moss source must be found. If Juncus squarrosus seed were present it would be expected that seed will rapidly disperse along waterways developed in the pit area following rehabilitation. Another potential source of Juncus squarrosus seed is nursery raised material from Stockton. Nursery quarantine would need to be incredibly effective to prevent the transfer of Juncus squarrosus to the Cypress mine site with this nursery raised material.

Rehabilitation methods

48. The ‘Rehabilitation Management Plan’ notes that the dominant method of rehabilitation will be planting nursery-raised seedlings. The preferred method of rehabilitation is direct transfer. However the proposed mine-stripping schedule only allows significant use of direct transfer in years 2, 3 and 6. Direct transfer would also be unachievable for much of the hillslope forest due to steepness and size of trees such as red beech in excess of 30 metres tall and 1 metre diameter.

49. Unfortunately this means that the best use cannot be made of the current vegetative cover for rehabilitation. In particular, the dense red tussockland of Happy Valley, which would be the easiest vegetation to use in direct transfer and as noted earlier is the vegetation association that will be most impacted by the proposed mine in terms of its representation within the Ngakawau Ecological District, will be of little use for direct transfer. This is because the majority is to be stripped in years 1 and 2 of the proposed mine, and rehabilitation of the north pit will not start till year 6. It would be far preferable if the mine were approved for much more of the red tussock to be used for rehabilitation work at Stockton or as the source of nursery material for replanting at Cypress.

50. Trials at Stockton which show how well direct transfer can work are indicative of what can be achieved for only a small proportion of the proposed Cypress mine site. Most of the Cypress site rehabilitation will rely on planting seedlings which will take much longer to achieve a natural vegetative cover. The suggested mine closure targets outlined in the ‘Rehabilitation Management Plan’ are in my opinion adequate to ensure that natural successional processes have begun and are likely to result in a final vegetation cover dominated by native species. However, I am unaware of any New Zealand mine site of this scale in what was previously a highly natural area that has been able to achieve similar targets. Probably the biggest challenge is the scale of the proposed rehabilitation. What has happened at Stockton to date, where it has been difficult to obtain sufficient propagules for nurseries to work with, and thus to reach annual rehabilitation planting targets is evidence of the challenges of such large scale reliance on plantings.

Post mine landforms

51. The effects on landscape including landforms are unavoidable due to the nature of opencast coal mining. The proposed remedy is to design the best “landscape fit” for the mine, and facilitate natural successional processes to create a natural vegetation cover.

52. Thus there will be some differences between the current landform and the post mining landforms. The most obvious of these is the overburden dump which will sit significantly higher than the existing landform. As it is impossible to recreate the sandstone pavement currently present here, the post mining vegetation will be shrubland and forest which differs from the low pavement vegetation currently present. I agree that this shrubland and forest will still be in context with the surrounding landscape.

53. As noted earlier, I agree that, other than transporting all overburden to the existing Stockton mine site or disposing of more in the south pit, the proposed overburden site is the best option in terms of minimising ecological and landscape impact. Although this means the loss of some of the distinctive sandstone pavement, it is in an area which has already been subject to some modification and is far preferable to some of the options which included covering small red tussock-filled basins.

54. The proposed north pit embankment will leave a 36m wide strip up to fifteen metres above natural ground level. Given that it is generally agreed that the current topography of the Happy Valley area contributes to the maintenance of red tussock cover by allowing cold air ponding, changes in topography such as that which would be created by the north pit embankment may alter these air circulation patterns. The ‘Red Tussock Wetland Boundary Management Plan’ notes that hydrology will be altered during pit excavation and embankment construction but the AEE concludes that hydrology will revert to close to its original pattern post-closure. It is important that this occurs if red tussock is to remain dominant. The post closure vegetation of the proposed north bank embankment is most likely to be a manuka strip through the red tussockland, a permanent reminder of the roadline.

55. The issue of post-mine hydrology is also relevant to the diverse aquatic bryophyte communities found in the proposed mine site and their apparent relationship to the diverse range of stream pHs present. The AEE notes that there will be some changes to the pH of streams during mining . For example the pH of water in St Pat’s Dam will be depressed and this will in turn lower the pH of St Patrick Stream at the point of discharge. Once mining is completed the AEE states that the pH is likely to return to the range of pre-mining pH. In order to maintain similarly diverse bryophyte communities to those currently present it is important that these targets can be met.

56. The eastern highwall will be left with exposed upper benches and batters. Hydroseeding with moss and seed of native herbs, flax and manuka is proposed to achieve an initial vegetative cover on the highwalls. This technique is still largely experimental and it is still unclear how much hydroseeding will speed up natural colonisation of these highwalls, and what effect it will have on the long-term composition of the vegetation here. Over centuries it is likely scrub and ultimately tall forest will grow up from the benches to hide these features, but they will remain obvious for many years prior to that.

57. The southern end of the south pit will be left about 20 m below the existing ground level. It is proposed to rehabilitate this area to tussockland – it is currently a mixture of low statured forest and scrub. The long-term vegetative cover will vary depending on how air circulates through this area, and how well drained it is.

Pest control to protect rehabilitated areas

58. Based on experience at Stockton to date, hares are likely to be the major threat to vegetation in rehabilitated areas. They will be a particular threat to nursery raised plantings. Hares have consistently proved to be one of the more difficult browsers to effectively control because they recover quickly following control due to increased breeding, and immigration from uncontrolled areas (Wong & Hickling 1999).

Fire

59. There is evidence of past fire in the vegetation pattern of parts of Happy Valley e.g. the presence of mountain flax and red tussock on steeper hillslopes where the expected cover is scrub or forest. Thus fire is a threat to the vegetation of this area and even though the likelihood of fire may well be low, the proposed fire safety programme and presence of fire equipment on site will be important to minimised the impact of any fires that do occur. This will be particularly important for rehabilitated areas that rely heavily on species such as manuka that burn relatively well.

Dust

60. The dust suppression methods suggested on pg 176 of the AEE to minimise effects on vegetation will in my opinion be adequate to protect vegetation based on evidence from similar methods used at Stockton.

Avoidance of effects on high value areas

61. As noted earlier, the ‘Red Tussock Wetland Boundary Management Plan’ has been proposed to protect some sensitive wetland areas adjoining the proposed Cypress mine. The development of this plan is supported, but its success in the long term is largely dependent on whether the hydrology reverts to close to its original pattern post-closure.

62. Avoidance of mining impacts on areas outside but close to the proposed mine footprint with high value bryophyte communities such as the bed of St Patrick Stream above the old dam site and bryophyte plot 32 will also be important. Consideration should be given to including these in any mine boundary management plan.

Summary and Conclusions

63. The proposed Cypress mine site contains significant indigenous vegetation as defined under section 6(c) of the Resource Management Act. In particular the area includes:
§ Part of the Upper Waimangaroa – Mt William RAP as proposed in the Ngakawau PNAP report which contains the greatest ecological diversity in the least modified condition of any of the RAPs identified in this report;
§ By far the best example of red tussockland within the Ngakawau Ecological District much of which will be removed during the operation of the proposed mine;
§ A very high diversity of bryophyte species including a high density of what are currently regarded as rare bryophyte species;

64. The proposed Cypress mine will have the following impacts on vegetation, flora and natural landscape:

  • Removal of at least 182ha of forest, scrub, red tussockland and coal measures vegetation from what is presently a highly natural vegetation sequence
  • As part of this, removal of 14.5 ha of dense red tussockland within Happy Valley which is widely acknowledged as the best and most diverse example of this association in the Ngakawau Ecological District.
  • Alterations to current landscape, and thus to topography, hydrology, and cold air drainage patterns and subsequent effects on what is presently a highly natural, extensive and complex vegetation pattern.
  • Increased potential for weed invasion, particularly gorse and weedy rushes, especially the heath rush Juncus squarrosus, and the effects of this species particularly in low statured vegetation both within and adjacent to the mine footprint.
  • Reduction in connectivity of natural habitats in Upper Waimangaroa Valley and thus effects on the movement of propagules and organisms across the valley.

65. The proposed rehabilitation is the key remedy proposed for the damage that will be caused to what is currently a highly natural landscape and vegetation sequence. The success of the rehabilitation faces some difficult obstacles, particularly:

  • The potential for weed invasion, especially Juncus squarrosus, of bare surfaces exposed by mining.
  • The sequence of mine development meaning the best possible use cannot be made of the existing vegetation for rehabilitation purposes and the resultant heavy reliance on nursery raised plantings the success of which has not to my knowledge been demonstrated for a mine of this scale.
  • The differences between the current and post mining landforms.

References

Bartlett, R. 2003. Vegetation of the proposed mine site. Unpublished report prepared in July 1998 and reviewed and updated in August 2003 for Solid Energy New Zealand Ltd by Mitchell Partnerships. 27 p, plus species list.
Champion, P.D. 1999. Selective control of weeds in New Zealand wetlands using herbicides – Interim report on field trials. Unpublished NIWA Client Report DOC90220 prepared for Department of Conservation. 20 p.
Department of Conservation. 2002. Comparison of the vegetation of Te Kuha with the vegetation surveyed for the Ngakawau Protected Natural Areas report. Unpublished report prepared by Technical Support Unit, West Coast Conservancy, July 2002. 22 p.
Glenny, D. 2003. Terrestrial Bryophytes – Survey. Unpublished report prepared in January 2002 and reviewed and updated in August 2003 for Solid Energy New Zealand Ltd by Landcare Research.
Johnson, P.; Gerbeaux, P. In press. Wetland types in New Zealand.
Kingett Mitchell & Associates Ltd. 1998. Flora of red tussock grassland to the south of Webb Stream, Waimangaroa Valley. Unpublished report prepared in July 1998 for Solid Energy International by Kingett Mitchell. 18 p, plus appendices.
Hitchmough, R. (compiler) 2002. New Zealand Threat Classification System lists 2002 Department of Conservation, Wellington.
McEwen, W.M. 1987. Ecological Regions and Districts of New Zealand. Third revised edition in four 1:500 000 maps. New Zealand Biological Resources Centre Publication No. 5. New Zealand Department of Conservation.
Ministry for the Environment. 1997. The state of New Zealand’s environment 1997. Ministry for the Environment, Wellington.
Norton, D.A.; Leighton, A.; Buckman, I. 2003. Response of red beech to fertiliser, Island Block coal mine, North Westland. New Zealand Journal of Forestry 48: 32-33.
Overmars, F.B.; Kilvington, M.J.; Gibson, R.S.; Newell, C.L.; Rhodes, T.J. 1998. Ngakawau Ecological District. Survey report for the Protected Natural Areas Programme. Department of Conservation, Hokitika. 178 p.
Simcock, R. 2003. Proposed Cypress Mine Rehabilitation Plan. Unpublished report prepared in April 1999 and reviewed and updated in November 2003 for Solid Energy New Zealand Ltd by Landcare Research.
Solid Energy New Zealand Ltd. 2003. Cypress Mine. Resource Consent Applications and Assessment of Environmental Effects.
Suren, A.; Glenny, D. 2003. Aquatic bryophyte communities of streams in the Upper Waimangaroa Valley. Unpublished report prepared in March 2002 and reviewed and updated in August 2003 for Solid Energy New Zealand Ltd by NIWA.
Wardle, J. 1984. The New Zealand beeches. Ecology, utilisation and management. New Zealand Forest Service.
Williams, P.A. 2003. The potential effects on vegetation of the Cypress Mine Project Area. Unpublished report prepared in July 2002 and reviewed and updated in August 2003 for Solid Energy New Zealand Ltd by Landcare Research.
Wong, V.; Hickling, G.J. 1999. Assessment and management of hare impact on high-altitude vegetation. Science for Conservation 116. Department of Conservation, Wellington.