The Assessment of Environmental Effects for the Timberlands West Coast sustainable beech management proposals of 1998 - 1999, written by Kit Richards. Timberlands West Coast Limited (New Zealand) (TWC) applied to the Buller and Tasman District Councils for Resource Consent hearings under the Resource Management Act 1991, to carry out sustainable forest management in about 98,000 hectares of beech (Nothofagus) forest. TWC is a State Owned Enterprise, created following the dis-establishment of the NZ Forest Service by the 1984 - 1990 Labour Government. In 1999, a newly elected Labour government, acting on preservationist dogma, moved swiftly to stop the Resource Consent hearings. In consequence, the public of New Zealand, and the world, was enied the oppertunity to learn about the excellent and world-leading sustainable forest management developed and proposed by TWC. This document is published here to help make the information more publically accessible.

Assessment of Environmental Effects


APPLICATIONS FOR RESOURCE CONSENTS

UNDER SECTION 88 OF THE

RESOURCE MANAGEMENT ACT 1991


Page four of this document.


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5. PLANNING CONTROLS

5.1 Buller District Council

Part of Station Creek Forest (Maruia Working Circle), all Inangahua Valley Working Circle forests and some of the forests in the Grey Valley Working Circle are located within Buller District.

5.1.1 Transitional Buller District Plan

By the time these applications are heard it is likely that the Proposed Buller District Plan will be fully operative, and accordingly the provisions of the Transitional Plan will be of no relevance. Nevertheless, the provisions are summarised for completeness.

5.1.1.1 Inangahua County Section

Most of the sustainable management estate within Buller District is located within the former Inangahua County and is thus subject to the Inangahua County section of the Transitional Buller District Plan.

Working circle forests within the former Inangahua County are located within the Rural, Forestry Production and Protection Forestry Zones.

“Forestry, in accordance with the NWASCO Forest Operations Guidelines, Bulletin No. 5, 1978”… is a permitted activity in all of these zones. These guidelines have since been superseded, but provide guidelines for various aspects of commercial forestry operations such as road construction, tree extraction, and post-extraction management. The purpose of the guidelines was to encourage appropriate soil conservation and management practises. TWCL will manage its operations to minimise soil erosion and adverse effects on water quality from its operations. The nature of the operations now proposed far exceed the standards envisaged at the time of the guidelines were created (which are still in force for the purposes of the Transitional Plan), and their conditions will not be exceeded.

The Plan also sets out specific conditions relating to forestry as follows:
  • recognition of soil conservation and water management principles and the recreational, scenic, amenity and ecological, and scientific value of the land;
  • the guidelines set out in the publication "Forest Operations Guidelines, National Water and Soil Conservation Organisation, Bulletin No. 5, 1978".
  • approvals from the Westland Catchment Board (now West Coast Regional Council) for forestry and ancillary roads on all lands with slopes exceeding 12° as a result of a notice issued by the Catchment Board pursuant to s34 of the Soil Conservation and Rivers Control Amendment Act 1959.
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  • no forestry undertaken in a manner or left in such a state that would be likely to facilitate soil erosion, of flooding, or cause deposits in water courses, or aggravate existing conditions that might lead to such consequences.
  • indigenous timber extraction must be carried out in a manner that is not detrimental to the natural environment, and that if by selective felling methods, or where clear felling is involved, it is for the purpose of conversion to agricultural use, or to exotic species, in accordance with the provisions of the Scheme (District Plan).
TWCL considers that the proposal does not contravene any of the conditions for permitted activities. Accordingly, the proposal is a permitted activity under the Inangahua County Section of the Transitional Buller District Plan.

5.1.1.2 Buller County Section

One forest in the Inangahua Working Circle (Orikaka Forest) is located within the former Buller County and is subject to the Buller County Section of the Transitional Buller District Plan. Orikaka Forest is located within the Rural Zone. “Production Forestry” is a permitted activity (Rule 4.1023) on all Class V land or land of lesser quality (i.e. Class VI - VIII). The TWCL proposal falls within the definition of “Production Forestry” in the Plan. All land in the sustainable management estate which is to be harvested is located on Class V land or land of lesser quality.

The only criteria for permitted activities is that the land be managed in such a way as to preserve the quality of soil for primary production and to prevent the depletion or erosion of soils. This condition will be satisfied.

5.1.2 Proposed Buller District Plan

All of the sustainable management estate falls within the Rural Zone in the Rural Character Area of the Proposed Buller District Plan.

As amended by consent order from the Environment Court in August 1999 Rule 5.3.2.4.2 provides for:

“Indigenous forestry extraction and incidental earthworks (including the construction and formation of stockpiling areas, skid sites, access points and tracking) undertaken in accordance with an approval under Part IIIA of the Forests Act 1949, or in the case of Timberlands West Coast Limited, a sustainable management plan certified by the Director-General of Agriculture and Forestry as complying with the requirements of Part IIIA of the Forests Act 1949.” as a limited discretionary activity. Matters over which discretion is limited are:
  • Effects on waterbodies, wetlands and riparian margins;
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  • Effects on habitats of any threatened or protected species;
  • Effects on archaeological, cultural or historic sites within the extraction area;
  • Protection of outstanding natural features and landscapes;
  • Protection of areas of significant indigenous vegetation or significant habitats of indigenous fauna identified using the criteria in Policy 4.8.7.4 as a guideline;
  • Effects on ecological functioning and the life supporting capacity of air, water, soil, and ecosystems;
  • Effects on the intrinsic values of ecosystems;
  • Effects on recreational values;
  • The location, extent and methods to be employed in harvesting operations in so far as these are relevant to the matters listed … above.
TWCL has prepared its Sustainable Management Plans to satisfy the intent of Part IIIA of the Forests Act. These plans have now been approved by the Director General and accordingly the rule applies to TWCL.

The clearance rule which previously applied to the operation, no longer applies. All aspects of the operation including earthworks and ancillary clearance for skid sites and tracking are now governed by this one rule. The Council has limited its discretion to the matters listed and must consider only those matters when exercising its discretion and when imposing conditions. The matters raised in Part II of the RMA are only relevant insofar as they relate to the matters which the Council has discretion over. This assessment of effects focuses on these matters, although some additional issues are canvassed for completeness.

The District Wide Rules in Part 7 must also be complied with for the activity to be a restricted discretionary activity. The only rules that potentially may not be complied with, are those relating to temporary signs, and access points to strategic routes. TWCL will make site specific resource consent applications for any sign or new access point that does not comply with the performance standards in the Buller District Plan before the sign or access requires erection or construction.

5.2 West Coast Regional Council

Buller District is located within the West Coast Region. The West Coast Regional Council controls land disturbance and earthworks through rules in the Transitional Regional Plan and Proposed Soil Conservation and Erosion Control Plan (Part 1). TWCL have obtained land use consents for works associated with its roading/ landing site network and helicopter harvesting activities. In addition, land use consents pursuant to s13 RMA (works in, on, under and over the beds of rivers) have been, or are currently being, obtained from the Regional Council to allow stream crossings. Details of all consents held from the West Coast Regional Council

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for this proposal, and previous consents held for roading and harvest activities in specific areas, are included in Appendix 10, Volume 2.

5.3 Tasman District Council

Tasman District is a unitary authority and as such undertakes both district and regional council planning functions. The Maruia Working Circle forests (excluding the part of Station Creek Forest located within Buller District) are located within Tasman District.

TWCL has already obtained a certificate of compliance and has sought a controlled activity consent for destruction and removal of up to 5 ha of native timber per legally defined site over any five year period. The proposal will not involve more than 5 ha of clearance per legally defined site in any five year period, and as such it is doubtful whether any further application to the Tasman District Council for this activity is required (other than for stream crossings). Nevertheless, TWCL makes the current application on a precautionary basis because the total clearance in each of the forests in Tasman District covered by this application may exceed 5 ha per 5 years. It is noted however, that even if the current application is required, TWCL is entitled to clear up to 5 ha per forest per five year period without a consent from Tasman District Council.

TWCL has calculated that the canopy gap created by removal of one tree is 32 m 2 . Accordingly, 5 ha clearance is equivalent to a maximum of approximately 1600 trees per five years leaving aside any clearance of tracks and landing sites.

5.3.1 Transitional Tasman District Plan

Parts of the Maruia Working Circle falls within the former Waimea County and are subject to the Waimea County Section of the Transitional Tasman District Plan. All forests are zoned Rural C. Rule 501.2 of the Transitional Plan states:

"Commercial forestry and the growing of trees for any purpose but excluding the logging or clearing of any areas of native forest, provided that the following shall be permitted:

(i) the logging or clearing of areas of native forest not exceeding 5ha in total over a period of five years;"

... in respect of proviso (i) above: The owner shall provide to the satisfaction of the District Planner a copy of a recent aerial photo of the locality which clearly and at reasonable scale identifies thereon the total 5ha proposed logging or clearance area or any intended staging of the work ...

"Note: the logging or clearance of native forest in excess of the above stated proviso is a conditional use in the zone. Refer to ordinance 502.10."

The total area of clearance in each of the sites which are the subject of a separate controlled activity application will not exceed 5 ha in total in any 5 year period. The

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total clearance over the whole of the Maruia working circle within the district will exceed 5 ha per 5 years.

5.3.2 Proposed Tasman District Plan

The TWCL forests are all located within the Rural 2 Zone.

Rule 17.5.10 in the Rural 2 Zone Rules is as follows:

“the destruction or removal of indigenous forest is a permitted activity if it complies with the following conditions:
  1. The activity does not contravene any other rule in Chapters 16, 17 or 18 of this Plan.
  2. The activity is subject to an approved sustainable forest management plan or permit under Part IIIA of the Forests Act 1949 and a copy of the approved plan or permit has been lodged with the Council.
  3. Condition (b) does not apply if the area of indigenous forest to be destroyed or removed is less than 0.1 ha of indigenous forest over a five-year period".

Rule 17.5.11 in the Rural 2 Zone Rules is as follows:

“the destruction or removal of indigenous forest that does not comply with the conditions for a permitted activity is a controlled activity if it complies with the following standards and terms:
  1. The area of indigenous forest destroyed or removed is greater than 0.1 ha and less than 5 ha over a five year period.
  2. The forest is not on a lowland alluvial site.
  3. The site lies outside the coastal environment area.
The controlled activity rule limits destruction or removal of indigenous forest to 5 ha over any five year period. Beyond that, a discretionary activity consent is required. Similarly, the transitional plan permits the clearance of up to 5 ha “in total” of native forest over any 5 year period. Neither plan indicates the extent of the area within which the clearance area is to be assessed.

TWCL interprets the references in the proposed plan to the area of destruction, as relating to the size of individual contiguous logging or clearance areas. These areas will not exceed 0.05 ha. It adopts this interpretation because, unlike the transitional plan, the rule does not refer to “total” clearance areas. Accordingly, the council’s concern appears to be with the size of each clearance area rather than with the total clearance per site or per forest. On this interpretation no consent is required at all for the intended operation under the Proposed Plan. Nevertheless, applying a precautionary approach TWCL has separately applied for a controlled activity consent to counter any argument that the rule refers to the total non-contiguous area of clearance. Even on this conservative interpretation, up to 5 ha of clearance in total is allowed within any 5 year period.

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Although neither plan uses the word “site” in the rule, the clearance area standard must relate to some geographic area. If the total non-contiguous area approach is taken (rather than looking only at the area of each contiguous logging site) then it is sensible for the rule to be read as referring to the total area of clearance within the scope of a particular application and in relation to a particular legally defined site.

In terms of Rule 7.5.11 (b) and (c), none of the forests to be harvested are on a lowland alluvial site as defined in the Proposed Plan, and the operation is not located within the Coastal Environment Area. Accordingly, Rule 17.5.11 (and the transitional plan) appear to allow for the removal of up to 5 ha of forest, in total per site over any five year period as a controlled or permitted activity. TWCL has separately sought controlled activity consents for that volume on a site by site basis. This current application seeks additional consent for clearance beyond 5 ha per forest per five years.

For convenience, the current application does not distinguish between sites. There is one application for all of the Maruia Working Circle forests located within Tasman District. As outlined earlier, it is doubtful whether this application is required at all, nevertheless TWCL has applied as a matter of precaution on the basis that the total non-contiguous area to be harvested from each forest will exceed 5 ha over a five year period. On that basis it could be argued that consent is required for all forests under Rule 17.5.12 of the Proposed Plan as a restricted discretionary activity and under Rule 502.10 (Transitional Plan) as a fully discretionary activity. In the Proposed Plan, the Council has restricted its discretion to the following matters:
  • the extent to which any retention of the forest is necessary to prevent instability, flooding, or erosion of land to maintain water quality;
  • the nature of any proposed activity following felling, and the suitability of the site for that activity;
  • the extent to which the proposal provides for regeneration of indigenous forest or sustainable yield management of the indigenous forest resource;
  • the significance of the indigenous forest affected and the impact of the proposal on the ecological, scientific, wildlife, recreational, scenic and tourist values of the area;
  • the extent of the reduction of the indigenous forest in the District should the applications proceed and the impact on the sustainability of that indigenous forest resource.
  • the extent to which additional land, "retired" land, or marginally productive land, is to be planted in indigenous forest on the applicant's property to balance any net loss of forest area due to the application proceeding;
  • the duration of the consent and the timing of reviews of conditions and the purpose of reviews;
  • financial contributions, bonds and covenants in respect of the performance of conditions, and administrative charges.

Consent will also be required in relation to the following rules, which are restricted Discretionary Activities:

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  • Rule 16.2.6 Discretionary Activities (Land Use) in the General Rules, as the following performance standard in Rule 16.2.4 is not met:

    (d) Frontage to Unformed Legal Roads

    The activity does not use an unformed legal road for legal or practical vehicular access to an activity on a site within an existing certificate of title.
  • Rule 18.6.6 Discretionary Activities (Land Disturbance) in the Special Area Rules, as the following performance standards in Rule 18.6.2 are not met:

    (g) All Land Disturbance

    No destruction or removal of indigenous vegetation is undertaken within 20 m of …the bed of any river or stream greater than 3 m average bed width…
    (i) Earthworks

    Earthworks involving the placement or removal of soil or debris within 10 m of any bed of a river or stream greater than 3 m average bed width, are for the formation, construction, reconstruction, removal or maintenance of any road, track … for the sole purpose of crossing the river or stream.
As with the Buller Proposed Plan, General Rules for temporary signs and access points to public roads must also be complied with or separate resource consents sought in relation to these matters. TWCL will make site specific resource consent applications for any sign or new access point that does not comply with the performance standards in the Tasman District Plan at the time the sign or access requires erection or construction.

5.3.3 Tasman Regional Plan (Land)

The Regional Plan Land became operative on 30 June 1998. Land disturbance associated with the roading network is subject to rules in this plan. All TWCL forests in the Maruia Working Circle within Tasman District are located within Land Disturbance Zone 1. Rule 6.1.2 provides for the destruction or removal of vegetation, soil disturbance or earthworks as a permitted activity subject to a number of conditions, all of which will be complied with.

Rule 6.1.2 (3) only permits earthworks associated with road construction within 10 m of a river or stream bed where the express purpose of the road is to cross the river or stream. There are likely to be situations where roads are required to run within 10 m of rivers and streams where the topography confines a road on a valley floor close to a river. This situation will be the exception, and in specific circumstances where the 10 m setback is breached by a road running parallel and not crossing a river or stream, a separate resource consent for land disturbance will be sought, which will allow site specific circumstances to be assessed and conditions imposed to mitigate any adverse effects. TWCL will seek such a consent where the earthworks to facilitate road construction are greater than 50 m from a river crossing. Otherwise, the road will be deemed to be for the express purpose of crossing the relevant river or stream.

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Consent for either a controlled or discretionary activity is required (Rules 6.1.4 and 6.1.8) where the formation, construction or reconstruction of any road is undertaken where the predominant land slope is greater than 25°. “Predominant Slope” is defined in the Plan and means “the most common natural slope of a more or less uniform area of ground at a scale consistent with any land disturbance activity”. In the context of this proposal, the roading network will be located in the valley floors which will have a uniform slope predominantly less than 25°. There will be situations where the cross fall is greater than 25° where the road traverses the end of a spur and is constrained by topography, but this will not be the predominant slope of the landform on which the road is constructed. Accordingly, these rules do not apply.

5.3.4 Regional Plan for Works in the Beds of Rivers and Streams

No rules have been developed to date for activities in, on, under or over the beds of rivers. Accordingly, construction of any river crossings required in conjunction with the roading network requires resource consent pursuant to s13 as such activities may only occur where expressly allowed by a rule in a regional plan.

5.4 Buller Water Conservation Order

Many rivers and streams in the general application area are subject to protection under the Buller Water Conservation Order. Of these, the only rivers running through TWCL estate which have been identified as potentially requiring river crossings for forest roading are the Rappahannock River and Station Creek, which run through Station Creek Forest in the Maruia Working Circle. These rivers have a “protection” classification. Road crossings of these waterways (i.e. fords, culverts etc.) if required, are not controlled by the conservation order (subject to obtaining necessary resource consents).







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6. ASSESSMENT OF ENVIRONMENTAL EFFECTS

6.1 Summary

It should be noted that this section summarises the information contained in the TWCL Sustainable Management Overview Plan and working circle Sustainable Management Plans. Where more detail on any of these issues is required, those documents should be referred to.

6.2 Indigenous Vegetation

6.2.1 Areas of Significant Vegetation

The protection of areas of significant indigenous vegetation (and significant habitats of indigenous fauna) is identified as a matter of national importance in s6 (c) of the RMA and is one of the matters Buller District Council has reserved discretion over. Neither Buller nor Tasman District councils have yet identified any areas of significance in their plans. The Buller plan reserves control over …protection of areas of significant indigenous vegetation or significant habitats of indigenous fauna identified using the criteria in Policy 4.8.7.4 as a guideline.

It is the council’s responsibility to provisionally identify such areas. Whether they are in fact significant will then be a matter for public debate and ultimately, determination by the council or the Environment Court. The guidelines in the plan are of some assistance in terms of identifying potentially significant areas but are not determinative. As far as TWCL is aware there are no areas of significance in the areas of the operation which have not already been reserved from harvesting. However, if areas of significance are identified by the Council, (or Court) TWCL is confident that these can be protected by the mitigation measures proposed, whilst still allowing for harvesting. The Act requires protection, not preservation of areas of significance. The detailed mitigation measures proposed by TWCL are intended to protect all areas of indigenous forest and habitat from adverse effects, irrespective of whether they are identified as significant.

6.2.1.1 Rare and Endangered Plants

North Westland is not rated as a critical region for threatened flowering plants and fern (Given and Kelly, 1976). In general most of the known presence of such plants have been included in the ecological reserves network of the conservation estate. The areas allocated for production forestry were accorded that status specifically because they were thought to contain few such plants. However, in some circumstances significant plants may be present within localised areas of the sustainable management estate.

The known endangered species are:
  • Coprosma wallii: a riverbed shrub which may be present in the Maruia Working Circle;
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  • Peraxilla colensoi, P. tetrapetala, and Alepsis flavida: all three threatened mistletoe species that are present locally throughout all working circles;
  • Bearded Orchid: a rare ground dwelling orchid possible present in Grey and Inangahua Working Circles; and
  • Brachyglottis traversii: a rare shrub possibly present in the Grey Working Circle.

The TWCL sustainable management plans do not provide specific prescriptions (rules) to identify and protect rare and endangered plants beyond reducing the impact of animal browsing by the control of goats and possums. However, in view of submissions made during the MAF “approval” process of the Plans concerning the impact of tree felling on mistletoe species, TWCL proposes the following additional measures to protect rare and endangered plants:
  • Operations staff will be trained to recognise all rare plants that may be present within working circles.
  • Operations plans will prescribe observance for the presence of rare plants during marking in annual operational areas and make specific prescriptions to either eliminate or mitigate any potential adverse impacts of roading or harvesting on rare and endangered plants.
  • TWCL will survey the actual frequency of felling of mistletoe host trees during sustainable management operations and research ways to mitigate the impacts of harvesting on mistletoe species through recognition and avoidance of felling host trees.
Further details on rare and endangered plants are contained in Section 2.2 of each relevant TWCL Sustainable Management Plan. Areas reserved from production to protect significant vegetation associations are shown on the maps in Appendix 6, Volume 2, and are described in Section 4.6 of this document.

6.2.1.2 Significant Vegetation Associations

Protection of significant indigenous vegetation has been recognised and provided at four levels in the sustainable management estate.

At the first level a process of identifying and reserving the most significant areas of indigenous vegetation was undertaken as part of the West Coast Forests Accord process. This resulted in a new national park and many other ecological and other reserve types being identified and transferred from the production to the conservation estate. The remaining areas were specifically set aside for indigenous forestry for either rimu overcut (to a specified completion date), or sustainable beech management. As a result of this and subsequent decisions, approximately 78% of the West Coast land area is managed by the Department of Conservation, with only 6% available for sustainable management by TWCL. In the Tasman District to, the management area is well replicated in the Rotoroa Ecological District and abuts, Nelson Lakes National Park, Kahurangi National Park and Lewis Pass National Reserve.

At the second level within the sustainable management estate, Recce plot data was analysed through ‘Twinspan analysis’ by Landcare Research Ltd (Allen 1996). Over the total estate the

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method failed to identify any extensive areas of vegetation types that could be considered rare or unique in terms of floristic composition compared with those already located within the conservation protected area network. Despite these findings, TWCL at its own volition has recognised additional areas of what it considered were special and reserved these from production. Some vegetation sequences are included within reserves for other purposes, which altogether constitute approximately 8% of the production estate.

TWCL recognises that all lands set aside for indigenous production have inherent conservation values simply as a function of their size. Therefore, notwithstanding that the most significant areas of indigenous vegetation were reserved from production, a third level of protection has also been provided for. Case law in New Zealand has already established that the protection of indigenous vegetation does not necessarily require preservation or the exclusion of harvesting activity. At the third level, provision for the protection of indigenous vegetation has been made by the very nature of the management system itself. The goal of natural forest management is to protect the forest’s biodiversity values and key management objectives have been specified as being the maintenance of a near-natural structure and diversity in the managed forest. The methodology for achieving these goals is described in more detail below.

Finally, in recognition of the intermix of significant and less significant species in the forest ecosystem, TWCL adopted a fourth level of vegetation protection within its sustainable management plans. Specific species such as miro, rata and kaihikatea have been excluded from harvest, while harvest of rimu will only be permitted in defined situations. Rimu will only be harvested from the Grey Working Circle and parts of the Inangahua Working Circle. The same conceptual approach to sustainable management of beech species applies equally to Rimu harvest (i.e. will be taken within 50 % of forest increment). As the stocking rate of rimu is only a fraction of that of the various beech species, the numbers of stems taken will be proportionally far lower averaging less than 0.2 trees per hectare each 15 years.

Further details on rare and endangered plants are contained in Section 2.2 of each relevant TWCL Sustainable Management Plan. Areas reserved from production to protect these species and other features are shown on the maps in Appendix 6, Volume 2.

6.2.2 Forest Structure and Ecology

6.2.2.1 Old Growth Forests

The prime management objective or philosophy for old growth forests has been described in Section 4.4.1 of the TWCL Sustainable Management Overview Plan. That philosophy seeks to protect these areas of indigenous vegetation by aiming “at forest structures which keep the rainforest ecosystem as robust, elastic, versatile, adaptable, resistant, resilient and tolerant as possible ….”. This protective philosophy has been reinforced through a series of “silvicultural objectives and policies”.

The relevant silvicultural policies are described as aiming to:
  • select and fell groups of trees that will create gaps corresponding in scale and pattern with natural replacement processes.
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  • encourage establishment growth and survival of forest regeneration with minimal site manipulation.
  • harvest a percentage of the forest growth in proportion across the range of diameter classes.
  • maintain if not improve the productivity (in quality and quantity) and relative site characteristics of the forest ecosystem.

Physical execution and compliance with the objectives and policies described above are attained through the exercise of “management rules” or “prescriptions”. The rules relevant to the protection of indigenous vegetation are fully listed in Section 8 (Mitigation Measures) of this document, and prescribe that among other things:
  • groups of trees must be harvested in gaps no greater than 0.05 ha, a size that is similar to the natural gap formation scale.
  • trees to be felled must be selected in proportion to their natural presence from across the diameter range to protect the natural structural and species diversity of the forest.
  • the harvest yield must be taken without bias in relation to the natural ratio of commercial and non-commercial trees to maintain the ecological and wood quality status of the forests.
  • the maximum return period between harvests is set at 15 years to ensure the spatial arrangement and intensity of felling groups is within the short-run range of natural occurrence.
  • the level of harvest yield is set at no more than 50 % of the estimated growth predicted over a defined period ahead (usually the return harvest period of 15 years). This level among other matters ensures large margins for error in resource estimation. It also provides for accommodation of significant losses due to random natural disturbances (e.g. major storms), and ensures that by careful tree selection criteria much of the yield can be obtained through subsuming the yield within natural mortality rather than in addition to it. This ensures that the average age of the forest is not substantially altered nor consequently the capacity of the forest to produce hole ridden trees for nesting birds.

These rules are all important from an ecological perspective. In simple terms, the theory of the selection system is that trees will die naturally in all age classes in the absence of management. The harvest simply focuses upon and skims off those trees in each age structure that are likely to be predisposed to natural mortality and at a rate equal to half the level of natural mortality (or growth) predicted for each working circle. The natural mortality in the forest will then decline in a compensatory manner as those predisposed to death are removed and consequently a near-natural forest structure can be maintained.

Limitation of the harvest across each working circle to 50 % of the growth or mortality will help ensure that management actions will not result in changes to forest structure beyond expected naturally occurring limits.

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The maximum return harvest period of 15 years for compartments will provide sufficient time for these compartments to recover before they are revisited for harvest. The length of the felling cycle is a major determinate on the ecological effects on the forest. As the full yield for the felling cycle is extracted from a group of compartments and then not revisited for a number of years, the longer the felling cycle the greater the potential adverse ecological effects on the impacted forest area. For old growth forests, the maximum 15 year felling cycle will allow the forest to re-stabilise and re-grow its lost volume, and is considered to be well within the biological recovery capacity of the forests.

TWCL will select and fell groups of trees that will create gaps corresponding in scale and pattern with the natural replacement processes within forest types. A maximum gap size of 0.05 ha has been prescribed, which, based on trials, can be achieved operationally. This gap size has been established through ecological research in beech forests in the Maruia Valley. The location of gaps around trees expected to suffer mortality over the next few years should ensure a near- natural intensity of site disturbances per hectare.

Different species have different regenerative strategies and light requirements. This requires that actual gap sizes that apply at any given site will be a reflection of a number of silvicultural and forest compositional factors. All of these are specific to the location and all must be accommodated within the marking decisions of the forestry professional making the tree selection. Detailed tree and group selection criteria operate below the specified maximum rule to ensure that species and site specific requirements are not overridden by inappropriate “fixed rules”. Harvest gap guidelines for various species and physical site considerations are included in Tables 17 and 18 (p. 96) of the TWCL Sustainable management Overview Plan. Particular consideration must be given to rimu where research and diameter class distributions suggest that while the species generally occurs as single trees and lacks intermediate regeneration, larger scales of disturbance than single tree harvest will be required to ensure regeneration. This can be achieved by removal of beech trees in combination with rimu extraction to provide gap sizes larger than those which would occur from single rimu tree removal. Also to protect the long term presence of rimu, new seedlings will always be planted where the old trees are removed.


6.2.2.2 Recovery Forests

In recovery forests, the current even-aged stands resulted from past severe modification often comprising initial near total destruction followed by aggressive regeneration of beech species. By the time they reach a stage potentially suitable for thinning, they will have developed a simple species and canopy structure. While the overall management objective remains similar to that for “old growth” forests, the policies and rules required to achieve that objective are different. At this stage (prior to management), these forests will be capable of:
  • providing continuity in landscape impression;
  • serving soil and water protection functions; and
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  • providing at least basic habitat values for many fauna species.
The relevant silvicultural policies required to “protect” these areas of indigenous vegetation are described as aiming to:
  • select and fell trees that will create gaps corresponding in scale and pattern to natural spatial ranges for the species concerned and that will encourage stand stability consistent with similar unharvested forests.
  • encourage establishment, growth and survival of forest regeneration with minimal site manipulation.
  • harvest a percentage of the forest in proportion across specified diameter classes so as to maintain a productive near-natural forest with a diverse composition of species and forest structure while returning the stand to a more all-aged structure.
  • return the standing merchantable biomass on the site to levels comparable with similar unharvested forest types.
In these recovery areas, the policies acknowledge the already modified nature of the forests, and the fact that potential timber quality is already improved. Provision is thus made to capitalise upon its state rather than return the stands to a significantly lower “natural” timber quality status.

The biggest risk is that without management intervention accumulation of many of these values will be postponed if the stands undergo natural collapse following intense intra-specifies competition.

The application of production thinning techniques to these stands will not compromise the values attained and should open the pathway to more all-aged stand development. As these stands gain in age, particularly if some trees are allowed to grow much older than the average stand age, biodiversity values will improve.

Physical execution and compliance with the objectives and policies described above are attained through the exercise of “management rules” or “prescriptions”. The rules relevant to the protection of indigenous vegetation in recovery forests are listed in Section 8 (Mitigation Measures) of this document, and prescribe that among other things:
  • management manipulation will be stand specific and based on a continuum of options reflecting the stands past history and current status.
  • trees must be harvested singly or in small groups.
  • the intensity of production thinning harvest at any visit will be no more that 12% of the merchantable volume.
  • the minimum period between returns shall be 10 years.

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  • the maximum number of returns to the stand under the "production thinning" regime will be five. This protects the genetic potential of these stands.

After no more than five thinning cycles these forests are expected to have attained a structure and composition more similar to that of “old growth” forests and will then be treated in the same fashion under the same silvicultural policies and rules.

This issue is discussed in further detail in Section 4.4.2.2.4 on (p. 109) of the TWCL Sustainable Management Overview Plan.

Forest areas subject to intensive felling in relatively recent times, less than 40 years, will not have attained a status suitable for production thinning. Limited suitable areas may be subjected to waste thinning silvicultural treatment. Such forest areas are typified by vigorous even-aged regrowth of beech saplings and poles at densities of several thousand or even tens of thousands of stems per hectare. The objective for managing recovery forests is to accelerate the time frame by which suitable stands will reach a production thinning status and thus shorten the time taken for such areas to achieve not only a commercially productive state, but also a status more similar to that of old growth forests.

The proposed management for these types of stands recognises that if left unmanaged, such stands will slowly acquire a tall forest stature that will be vulnerable to windthrow and disease attack due to the even-aged nature of the stands. Only after several cycles of stand collapse and rejuvenation will a more “old-growth” forest structure develop. The management proposed for these stands is that they be thinned early down to much lower densities where the stand status is suitable. By doing this, the process of development to tall multi-tiered forest that can then be managed under the production thinning regime and convertion back to all-aged forest is markedly accelerated.

The modification processes involved are not considered to pose any adverse environmental effects since the young forest is already highly modified, monocultural and lacking in diversity. In fact the management proposed will be an environmental benefit. The only adverse effect to being managed would be over-thinning leading to mortality and collapse of the remaining stems after thinning. This effect can be avoided by maintaining an adequate final crop stocking of no less than 400 trees per hectare for trees averaging greater than 12 metres in height and no less than 1,000 trees per hectare when the height average is less than 12 metres down to a minimum average height of 4 metres.

6.2.3 Canopy Cover

Structural diversity in all forest types and the avoidance of forest fragmentation will be ensured by management rules pertaining to the adopted selection systems.

Rules restrict:
  • gap sizes to those of natural event scales;
  • minimum distances between gaps;
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  • the intensity of harvest to levels of natural mortality already measured in these forests; and,
  • the cycle of disturbance to a time long enough to ensure canopy stability and recovery.
These rules (already discussed in the preceding sections) are designed to achieve the policy of maintaining continuous canopy cover and a spread of regeneration ages. This will retain the tall forest canopy and ensure a total permanent interconnecting link of forests with the reserves network established on the DOC estate and the special biodiversity reserves to be reserved from production within the TWCL sustainable management estate. These measures will minimise, to the greatest extent possible, any risks of forest fragmentation and will maintain levels of disturbance, distribution and intensity to those within the natural spectrum. Harvesting over the old growth forest area will circulate over a 15 year maximum harvest cycle (minimum 10 year return period for recovery forests), ensuring dispersion of disturbance and ample time for recovery and stabilisation of disturbed environments.

6.2.4 Pinhole Borer

Pinhole borer has traditionally been viewed as the single greatest hurdle to effective beech forest management for timber. The borers, in excess, are capable of causing severe degradation and even death of forest trees, and epidemics can be induced following disturbance of the forest by either human or natural factors. Traditional silvicultural techniques aimed at defeating the impacts of these insects were at odds with the objectives and policies sought under present management.

The following is an extract from the main findings of a review of past research on Platypus (McCracken, 1994; page 1):

"New Zealand has three species of Platypus pinhole borers, all of them native. Platypus beetles attack living and apparently healthy beech trees, stumps, freshly felled logs and larger branches, and occasionally green sawn timber, as well as a wide range of other native and introduced tree species. Their tunnels penetrate the inner sapwood and give access to the pathogenic Sporothrix spp. fungus. Once in the inner sapwood Sporothrix spreads vertically and laterally, creating dead, stained, 'pathogenic wood', and will persist even if the Platypus attack is overwhelmed by the natural defences of the tree. Should Sporothrix succeed in sufficiently obstructing xylem water flow, infected trees will suffer dieback or death. Infected trees that survive are susceptible to stem rot from saprophytic fungi that gain access to pathogenic wood through wounds, root rot or further pinhole attack. In themselves Platypus are non-pathogenic; it is their association with Sporothrix that makes them lethal.

Platypus beetles can fly at least 1 km and possibly up to 4 km in search of suitable host trees. Host attraction is related to growth rate, damage, stress, or existing attack by the same species (except in P. caviceps) and considerable effort has been invested in examining the nature and composition of olfactory attraction and pheromones. Sporothrix infection of the inner sapwood appears to be incidental to the attack,


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Platypus simply providing a convenient pathway. Natural defences to Sporothrix in beech and other species appear to be in the outer sapwood and Platypus tunnels allow these to be bypassed.

Of the three species P. apicalis is potentially the most damaging to managed stands. Males are capable of attacking the lower main stem of apparently healthy trees of any age, although attack is unlikely to survive if dbh is less than 17 cm. Attracting both further attacking males as well as females to attacked trees reinforces the attack".


Hosking (1996) concluded the only identifiable (disease) risk associated with beech management was that from pinhole borers. In particular, a regular frequency of localised significant disturbance associated with poor hygiene or large sources of woody breeding material were noted as the contributing factors to avoid or mitigate. Unmitigated, explosions in the resident pinhole populations could otherwise occur.

The combination of research as well as practical experience gives compelling support to a low impact, passive approach to management. Pinhole borers as native insects have always been present and suitable brood material has also always been present as a function of natural forest mortality. The combination of proven high solid wood recovery and management systems that will not exacerbate pinhole borers means that through small scale, temporally and spatially separated disturbance events, natural levels of pinhole can be tolerated in beech forests. This new understanding means that the management objectives and policies described for old growth and recovery forests are now in alignment and in fact contribute to the requirements for pinhole borer management.

TWCL’s prime objective with respect to pinhole borer is to implement a management system which maintains patterns of borer attack within the long run natural occurrence of the forest and prevents any outbreaks that as a result of the applied management could threaten these vegetation areas. To achieve this, the following measures will be implemented:
  • Prevention of damage to trees adjacent to felled groups or the removal of such damaged trees as part of the permitted yield;
  • Cutting of logging wastes on site into piece sizes small enough to accelerate drying or breakdown;
  • Treatment of stumps with urea or a similar environmentally acceptable substance that does not discourage attack but minimises brood emergence;
  • A Platypus monitoring system has been implemented. It applies statistical methods to detect whether there is any increase in the incidence of pinhole attack on the adjacent future crop trees. If monitoring shows a significant increase in pinhole attack there are a variety of additional measures to increase forest hygiene that can be applied as well as a number of options currently being researched. However, overall, practical experience to date over a number of sites is raising the expectation that less rather than more will need to be done in the area of hygiene.
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6.2.5 Windthrow and Snow Damage

Wind is a natural cause of damage in beech forest and occurs continually throughout forests. Under most circumstances its effects are localised as the damage results from the toppling of a large old or rotten tree. Occasionally, some further small adjacent pole stems may also topple due to loss of support and exposure to increased wind.

Exposure to wind turbulence along hard forest edges created by harvesting can increase windthrow above the natural levels. Normally, the bigger the harvested gap the greater the risk up to the point that the edge losses relative to area of a cleared patch becomes insignificant. This is the case for larger felled patches. However, the alternative is to keep the harvested site so small through selection systems and gap sizes that there are no hard edges and the harvesting induced disturbance remains directly comparable with natural scales. This is the approach proposed in this application.

Exposure to geographically funnelled winds and shallow soils are the contributing factors for which management responses have little to offer. TWCL propose a post event approach in these situations with effort simply directed at recovery of downed timber as and when the blowdowns occur.

Wind has also been the cause of extensive damage in some managed stands where thinning has been carried out in pole stands (Kirkland, New Zealand Forest Service, 1965). If and where thinning is undertaken in already even-aged stands, the single most important action is to restrain the intensity of thinning to ensure individual trees are not overly isolated or exposed and the canopy is relatively continuous. This matter has been addressed in the rules covering the scale and intensity of harvest in recovery forest.

‘Wet’ snow has a similar effect to wind in causing forest collapse. Dense natural regeneration is a normal response to such events. Nevertheless, snow damage is more difficult to plan to avoid, and management can really only deal with the aftermath by way of salvage of utilisable material from damaged stands.

6.2.6 Disease, Stress, Physiological Drought and Pathogens

A report was commissioned from the Forest Research Institute (Hosking, 1996) to canvass the likely disease risks associated with beech management.

In relation to disease risks other than pinhole borer, Hosking concluded that, while periodic disturbances and their associated disease outbreaks naturally affected beech forests, these were normal events that would repeat on a localised level from time to time. Overall, it was concluded that there was a low risk of any unexpected effects from management and that external pathogens also generally presented a low risk. For those vectors and pathogens that might pose a risk to the forests, effects were likely across the whole estate. These would be a concern of a national conservation scale rather than a byproduct of controlled management of forests for timber.

Beech forest can suffer from physiological drought including:

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  • Summer desiccation of seedlings caused by sudden exposure to hot, dry conditions when they are rooted only in the duff layer, or when they are suddenly exposed to sun scorch on the leaves;
  • Summer drought when the water table is lowered to such an extent that even mature trees are dehydrated;
  • Winter desiccation of seedlings, saplings and pole trees caused by cold or frozen soils on sunny winter days when insufficient soil water is available to meet transpiration demand;
  • Winter desiccation caused by dry winds, especially in stands that have been over-thinned; and,
  • Winter desiccation of tender foliage insufficiently matured before onset of winter. All the above lead to stress, and stress can lead to attack by pathogens. Stress can be minimised (though not entirely eliminated) by:
  • Keeping young seedlings sheltered from the excesses of summer heat and exposure, or winter frost, through retention of a sheltered environment (the small allowable gap size); and,
  • Thinning natural even-aged regeneration on time and as appropriate to keep trees vigorous and therefore less stressed from competition, but recognising sites prone to winter desiccation, and ensuring that the thinning prescription on such sites is not excessive.

6.2.7 Biomass Removal

Most forms of natural disturbance, even though they may be of a catastrophic nature, result in the stand biomass being retained on site - exceptions being linked to induced erosion and nutrient leaching. On the other hand, harvest of trees for production of wood invariably results in removal of biomass. The outcome of this is the direct removal of a small proportion of the nutrient pool present at the time of harvest. Additionally there may be, over time, a reduction in the average level of coarse woody debris (CWD) in the litter zones, and thus a reduction of habitat for litter decomposers and other invertebrates that are linked to this particular ecosystem. This may create the potential for depletion of nutrients and may have long term effects on soil fertility.

These effects are an inherent component of any primary production system and are unavoidable where timber production is an objective of management. However under the proposed management system, rules have been specified to reduce such effects. The primary rule is that TWCL will adopt the practice of retaining all defective wood and branch material on site (even where this could be used in fuel or chip markets) to provide invertebrate habitat and to ameliorate the consequences of any nutrient drain. This will ensure that between 70 to 80% of all vegetative biomass is retained on site. In addition, the rules requiring small sized natural gaps serve to prevent temperature extremes and exposure leading to volatilisation or leaching of nutrients. The use of helicopters also prevents surface disturbance and associated fine sediment run off.

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Even though trunk wood itself contains relatively few nutrients, the bark of the beech species does. It is not known to what extent removal of nutrients in logs is balanced by atmospheric accretion and release of new minerals from parent material. However, some research initiatives are underway to better understand these matters and TWCL will take note of any findings and modify management practices where feasible to accommodate relevant results. Even so, any rates of nutrient depletion will be small and of a lesser magnitude than any other currently practised land based production system. It is expected that a standardised monitoring system introduced as part of a national system, and to be implemented in these forests, will be unable to detect changes in soil status.


6.2.8 Pests

Pests (e.g. possums, deer, goats etc.) which damage indigenous vegetation are already located within the sustainable management estate, and the wider indigenous forest resource. Suggestions have been made by opponents of the scheme that roading access in association with beech management will increase forest access for pests and increase pest attack.

The within-forest geography of the sustainable management estate, with the presence of approximately 65-70% of the road network already in place, and river valleys and ridges providing easy natural access into the heart of the forest stands, is such that pests (and predators) are already present throughout the forests. It is considered very unlikely that sustainable beech management will have any perceptible effect on the overall distribution of pests within the forests provided that the gap size and spatial and temporal distribution are at similar levels to natural forest as has been prescribed in the silvicultural rules.

Management will, however, provide the opportunity for TWCL to implement pest (and predator) management strategies that might otherwise not be implemented at all, and certainly are unlikely to be able to be as cheaply implemented in adjacent areas of conservation estate. TWCL will commit a proportion of revenue to pest and predator control, but as with all land management authorities caught up in the intractable problem of controlling introduced pests, cannot yet guarantee the success of any such strategies. Nevertheless, early signs of success are becoming apparent in the similarly managed forests of Saltwater and Okarito where bird numbers are on the increase following ground based pest management utilising low quantities of poison applied cheaply and repeatedly due to good access.

The beech production estate in general terms is stocked with plant species that are generally less palatable to pests such as possum and deer. The prolonged presence of these pests and the relatively low numbers as established from observation during the wildlife surveys indicates that in terms of protecting the indigenous vegetation, the damage has already been long done. This cannot be reversed other than by extremely intensive eradication and the pests themselves thus rate as only a moderate to low vegetation protection priority. Goats however remain capable of causing significant damage to indigenous forest. In the TWCL estate goats have a very limited distribution due to imperfect (wet) conditions. There are a limited number of areas where differing habitat conditions do allow populations to build. Management remains committed to treating these “hotspots” mainly in the Station Creek (Maruia) and Orikaka/ Ohikanui bluff areas.

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Possum as a vegetation pest will be mainly controlled through the general control schemes and local initiatives to which the Company already contributes directly through rates or through encouragement of commercial culling. Higher levels of control will be undertaken as part of threatened fauna protection schemes described later, or if the described methods above fail to keep numbers moderate to low.

Overall, beech management will not exacerbate the distribution of pests but provides the opportunity for improved control. There will be much less pest control in these areas without the operation of the beech management scheme.

6.2.9 Rotor Wash

Experience has shown that in some circumstances on steep slopes over 30°, with shallow soils, after prolonged wet periods, and in still air conditions, helicopter rotor wash can cause individual stems to fall. Operations will be temporarily halted, or harvesting diverted to alternative sites if such circumstances arise, or only continue with a longer ‘long-line’ or in conditions of light to moderate winds.

6.2.10 Roading

The adoption of aerial harvesting is the single most important factor that allows TWCL to mitigate any adverse impacts from roading. Its benefits accrue directly from a dramatic reduction in the density of roading and tracking required to access the forest. A comparison with roading densities from other methods of harvesting is shown in Table 5 below.

Table 5: Indicative Road Density in Various Terrain and Harvest Configurations

Harvest System Terrain Harvest
Technology
Road Density
m/ha
Clearfell Flat Hauler 14
Clearfell Hill Hauler 32
Clearfell Rolling Tractor 14-20*
Coupes Flat Tractor 20-30*
Coupes Hill Hauler 32-80 *
Group Tree All Helicopter 1 - 3
*These figures could include low grade tracking for up to 50% of the total.

In the forests subject to these plans, much of the required in-forest roading network is already in place (approximately 81%). Cumulative impacts derived from additional roading will be minimal. In the worst case situation, less than 0.25% of the current forest area will require clearance for additional roading infrastructure. In these cases, trees in all diameter classes will need to be clear felled and it is recognised that this may have localised environmental effects on forest ecosystems, although these effects will be minor in the context of the overall management of the sustainable management estate.

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To minimise the impacts of roading on indigenous vegetation, trees in merchantable sizes felled for roading will be inclusive rather than additional to the permissible harvest.

The potential also exists for weeds to be imported in association with road construction, with seeds being contained within imported gravels etc., as well as through invasion into harvesting gaps. This issue was raised repeatedly by submitters to the MAF process opposed to management of the forests. TWCL is satisfied that the rules for vegetation protection, road construction and pest control are adequate to avoid or mitigate this concern. This will be achieved by:
  • the use of helicopters minimises the additional road network required;
  • the small size of gaps created by harvesting leads to the maintenance of a semi-shade in-forest environment that is not conducive to the needs of light demanding pioneer weeds;
  • the lack of soil disturbance through aerial extraction means most small seeded pioneer weeds will not germinate successfully;
  • the construction of roads using local internal sources of road metal and particularly the gaining of metal where possible from sub-surface sources free of long lived seeds such as gorse;
  • the construction of roads to the minimum width corridor possible to ensure a relatively closed shady environment;
  • maintenance by TWCL of a programme of spraying of its forest roads to control weeds; and,
  • weeds that can survive as an under storey species often have larger animal dispersed seeds e.g. Himalayan honeysuckle. The control of goats and livestock is relevant to the control of this and similar weeds.

In the event of abandonment of beech management, weeds especially gorse may initially colonise roads. Experience has shown that repeated disturbance or partial eradication only serves to slow the process of succession to natural indigenous forest species. Sufficient decommissioning of the road to prevent continued vehicular access is the best strategy to ensure restoration as part of the natural process of succession.

Impacts of roading on other aspects of the forest environment are discussed in the relevant sections below.

6.3 Habitat for Indigenous Fauna

6.3.1 Significant Habitats of Indigenous Fauna

Provision for the protection of significant habitats of indigenous fauna is identified as a matter of national importance in s6 (c) of the RMA. As noted above the Buller Plan reserves discretion over this matter but does not identify any such areas. TWCl believes that all habitats of significant fauna will be avoided or protected under its proposal.

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As with significant indigenous vegetation, significant habitats of indigenous fauna have been afforded four levels of protection.

The first level was undertaken as part of the West Coast Forests Accord process. Key lowland habitat sequences were identified and reserved. Equally important, a large band of lowland forest running south from the Buller river in the north, through the forests of northern Te Wharau and the East Inangahua then across to the upper Grey valley and on down to Hochstetter forest north of Greymouth was protected. This wildlife corridor was established for the express purpose of providing for fauna protection against habitat isolation and fragmentation from natural causes and the then proposed clearfell based beech management. The corridor was designed to link all the main ecological reserves in the region.

At the second level, extensive surveys have been undertaken of the Grey, Maruia and latterly Inangahua forests to establish the presence and distribution of birds and bats (Buckingham et al 1995-1999) and Lizards (Whitaker 1997 &1999 ) within the sustainable management estate. As a result of these surveys, additional areas of what were considered special habitat types were reserved from production (see maps in Appendix 6, Volume 2).

At the third level, there is provision for the protection of habitat by the very nature of the management system itself. The company recognised the findings of past research that indicated the significance of the structural composition of the forests, particularly in relation to large old hollow trees and their importance for nesting and food. As explained above, the goal of natural forest management is to protect the forest’s biodiversity values.

Finally, in recognition of the intermix of significant and less significant species in the forest ecosystem, the Company adopted a fourth level of vegetation (habitat) protection within the sustainable management plans. Specific species such as miro, rata and kaihikatea have been excluded from harvest, while harvest of rimu will only be permitted in defined situations, and key management objectives have been specified as being the maintenance of the structure and diversity of the managed forest. How these goals are achieved is described in more detail below.

Kiwi habitat per se does not require the same levels of protection as for some other birds as Kiwis do not use the actual trees being removed as habitat, and the low intensity of operations will allow retention of sufficient forest cover to maintain broader habitat requirements. Management will allow a degree of intervention against predators which is not occurring at present, while dogs will be banned from the estate during the breeding season.


6.3.2 Rare and Endangered Fauna

North Westland is habitat to a range of species, many of which are in decline due to the effects of past habitat loss and in more recent times the ravages of pests such as possum, stoats and wasps. Within the forests proposed for beech management birds and bats have been identified as the most at risk from timber management. The areas allocated for production forestry were accorded that status specifically because they were thought to be of lesser significance in

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general for these species. However, surveys have confirmed the presence of important fauna within areas of the sustainable management estate.

The known rare and endangered species are listed in the relevant parts of Section 2 above, and also Sections 3.2.2.1-3.2.2.4 of the TWCL Sustainable Management Overview Plan.

The Management Plans provide a number of specific prescriptions to identify and protect rare and endangered fauna. However, in view of private submissions made during the MAF “approval” process concerning the potential impact of tree felling on bat roosts, TWCL proposes the following additional measures:
  • Operations staff will be trained to recognise and report rare plants or fauna that may be present within forest working circles. A field guide to threatened species within the Timberlands estate has already been developed for this purpose.
  • In those forests where the presence of bats has already been established by survey, prime "bat habitat" zones will be defined within these forests and rechecked for presence of bat roost trees or bat concentrations prior to the commencement of harvesting operations and such key areas avoided.
  • Kiwi are not expected to be adversely affected by the operation, except potentially during the breeding season. For this reason, where a presence has been established by general survey, either further surveys will be undertaken and operations moved to unoccupied areas or the operations will be timed outside the breeding months.


6.3.3 Protecting Species

6.3.3.1 Avifauna and Bats

The prime management objective or philosophy for old growth forests has been described in section 4.4.1 of the Overview Plan. That philosophy seeks to protect these areas of indigenous vegetation by aiming “at forest structures which keep the rainforest ecosystem as robust, elastic, versatile, adaptable, resistant, resilient and tolerant as possible…”. This protective philosophy has been reinforced through a series of “silvicultural objectives and policies”.

The relevant silvicultural policies are described as aiming to:
  • Maintain landscape, wildlife habitat, and soil and water values, as much as possible.
  • Select and fell groups of trees that will create gaps corresponding in scale and pattern with natural replacement processes.
  • Harvest a percentage of the forest growth in proportion across the range of diameter classes.
  • Maintain if not improve the productivity (in quality and quantity) and relative site characteristics of the forest ecosystem.

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TWCL has concentrated much of its biodiversity research into comprehensive bird surveys of the sustainable management estate. The aim has been to benchmark numbers of native birds before sustainable management begins and to identify any potential risks to birds posed by management (Buckingham & Nilsson, 1994; Buckingham & Brown, 1995; Buckingham, 1997, Buckingham, 1999). These surveys are the most comprehensive yet undertaken and provide important data on the relevant abundance and distribution of species.

Special searches were made for rare species, such as little spotted kiwi, blue duck, yellowhead, bats and South Island kokako. Blue ducks and bats are present and it is possible that South Island kokako is not yet extinct.

The sustainable management estate contains other species of national importance, including great spotted kiwi, New Zealand falcon, South Island kaka, yellow-crowned parakeet, and long tailed bats. Though not found in the forests during survey, short tailed bats may still be present. Numbers of these species are low and fragmented except for parakeets that are common in the Maruia Valley. Most of the other native bird species are either declining or stable in the face of continuing predation.

Various studies into the effects of past clearfell harvesting techniques on avifaunal populations have generally concluded that such activity is detrimental to the existence of some species, particularly hole nesters, seed and nectar feeders and those with large habitat ranges (O’Donnell & Dilks, 1987; Spurr, 1987). These findings are not surprising as the study sites involved harvesting systems that largely or completely removed the forest from localised areas over short periods. There were few areas of old regenerated forest from which to draw comparisons. Of practical necessity, these studies looked at localised site impacts and their results are undoubtedly real. However, such work cannot accurately predict outcomes from low intensity harvesting systems undertaken over a large continuous forest cover and diverse habitats of thousands of hectares. Furthermore, the results cannot be readily verified under the type of management proposed.

International studies by the International Union of Conservation and Nature (IUCN) (1988 to current) suggested that extinction by timber harvesting alone is unlikely to happen beyond rare and localised events where vulnerable and specialised habitats are destroyed. Heywood and Stuart (1992) came to the conclusion that there is little actual evidence for the reality of mass extinction rates that some authors derive from theoretical models.

Nevertheless, research work in New Zealand in the late 1980s indicated that some bird species might be regarded as specialised in their habitat requirements. It also concluded that certain components of forest structure and composition could serve a disproportionately important role in maintaining viable populations, other matters being equal (e.g. no or few predators). Much of this work (O’Donnell & Dilks, 1986) involved observation of some species of birds in relation to their use of different sizes and species of trees for feeding and breeding. Some of the prime findings of relevance to these plans are as follows:
  • In South Westland mixed beech and rimu forests, 92% of kaka and 40% of parakeet observations occurred in rimu trees greater than 60 cm dbh;
  • In the same forests feeding usage by bird species was limited to relatively few tree species;

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  • In Fiordland beech forests, 94% of parakeet nesting observations occurred in red and silver beech. In the red beeches 40% of observations occurred in trees between 70-110 cm while a further 46% occurred in trees greater than 110 cm dbh.

More recent work (Elliot et al, 1996), concerning parakeet and mohua (yellow head) in Southland beech forests has continued to conclude that removal of large old red beech trees could be a threat.

It is interesting to note that more recent ecological understanding and emphasis has concluded that, in general, on a wide scale, predation and competition are the driving force for continued extinction of many of the presently rare species such as kaka, irrespective of timber harvesting (Grant, O’Donnell & Garland, 1993).

A cautious stance has nevertheless been adopted because:
  • while limited previous work has indicated that in lowland beech forest areas in the lower Grey Valley, bird numbers in unharvested forest might be similar to that in older regenerated harvested forest;
  • the recent surveys conducted by TWCL have tended to confirm original observations, that lower numbers of species such as great spotted kiwi, kaka, parakeets, riflemen and robins are in the most recently heavily logged forests;
  • though localised concentrations of bellbird, parakeet, riflemen, robin and kiwi are present in older modified areas which suggests some tolerance of even significant modification.

Under selection systems, especially with the use of aerial harvesting, individual or small groups of trees can be economically harvested with minimal damage to surrounding canopy and subcanopy forest vegetation. Furthermore, wood utilisation studies by TWCL have confirmed that large old trees were generally the most defective and of low commercial worth. The management system was thus specifically designed to incorporate a “precautionary principle” as follows:
  • The felling of trees in groups according to natural scales was designed to maintain near continuous canopy conditions, deter significant changes in pest and predator use of gaps and maintain near natural growth rates to ensure average forest age did not significantly decline.
  • The felling cycle was adjusted so that the level of removal of trees within each size class was close to the extreme minimum for mathematical models used to predict bird losses due to harvest under harsher management regimes.
  • Upper diameter limits were set above which trees could not be felled to protect important habitat function.
  • Harvest rates were established at 50% of expected growth to ensure natural mortality processes continued within the forest.
  • Yields are to be removed proportionately from across the allowable diameter range to protect the forest habitat structure and ensure a supply of ongoing large old trees grow through to replace those that eventually die naturally.

Based on research undertaken or reviewed, specific measures have been undertaken to minimise impacts on native birds and bats. In the case of kiwi, the prime mitigation strategy
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in addition to those already described in relation to avoidance of disturbance over the breeding season is the banning of dogs. These measures are detailed in Section 3.3.2 of each TWCL working circle Sustainable Management Plan and are also detailed in the Mitigation Measures section of this document.

6.3.3.2 Fish

Impacts on recreation fisheries and waterbodies per se are discussed in Sections 6.4 and 6.8 below.

A number of native fish species are located within water ways in the sustainable management estate, some of which are threatened. These species are detailed in Section 2.2.2.2 above. Fish species are vulnerable to changes in water quality, sedimentation and temperature. Impacts on native fish species will be minimised by riparian management practices (i.e. restrictions on roading and logging adjacent to medium and high priority streams). Where stream crossings are required, crossing structures will ensure fish passage is maintained. The use of either carefully placed, removable temporary crossings or full span crossings on high priority streams will minimise any adverse impacts upon fisheries from stream crossings.

Low priority streams also have some habitat value for native fish. These streams are seepage points, depressions and channels that may flow intermittently and/ or permanently flowing water bodies with a maximum flowing channel width of 1 m in low flow conditions. Riparian management is not proposed in these situations. However, debris and slash will not be allowed to accumulate in these streams and felling of trees in these waterways will be avoided where practicable.

Riparian margin protection is discussed in Section 6.4 below.

6.3.3.3 Reptiles

As with birds, lizards are known to form a dietary component of predators, particularly stoats. The threat to any already rare species, given specialised or localised habitat requirements, is likely to be terminal over time. Additionally, the lizards’ own dietary requirements are probably at least periodically under pressure in years when wasp numbers are high in these forests.

In order to assess the risks posed to reptiles from forest management, a review of the distribution of and potential impacts of management upon reptiles was commissioned by TWCL (Whitaker, 1997, 1999).

Whitaker identified that the beech forests and their associated podocarps and occasional pakihi shrublands all offered suitable habitat for arboreal forest geckos and green geckos. However, he concluded that if the examples of forestry selection systems he visited were the norm, there would not be any significant impact upon lizards provided that such management did not create any ongoing cumulative secondary effects. Anything that promoted an increase
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in wasp populations, which compete for the same food would be particularly detrimental. Moller (1996) also noted that lizards were a dietary component of stoats and rats.

Whitaker also noted that the species occupying the beech production estate and their habitats are widely distributed and well protected within the conservation estate. As such, no specific reservation requirements were recommended.

6.3.3.4 Invertebrates

In the Parliamentary Commissioner for the Environment’s review of the draft beech management plans (1995), criticism was made of the lack of invertebrate survey. Subsequent advice sought by TWCL indicated that such surveys were of extremely limited value with a very poor cost benefit for the following reasons:
  • The lack of an appropriate, standardised, objective methodology to effectively assess large-scale areas;
  • There are undoubtedly very large numbers of species not yet properly described in New Zealand;
  • The fact that no such surveys have been conducted elsewhere or even on adjacent conservation lands, thus confounding any ability to determine the status of any unknown species in relation to population stability, rarity or viability;
  • The sheer scale and cost of the studies; and
  • The fact that the natural variability in distribution in time and space of invertebrates makes the statistical power of surveys very low.

The few studies of invertebrates within beech forests have concentrated on economically important pests or rare invertebrates in isolated habitats. In addition, Moller (1996) noted that most of the larger and (usually) rarer invertebrate species were, like so many of New Zealand’s threatened species, subject to severe pressure from predators, especially stoats and rats. Even small insects, including spiders and caterpillars which are important foods for birds, were being pressured to an as yet undetermined extent by the existence of large wasp populations in these forests.

Evans (pers comm, 1996) also noted similar impacts, but in addition expressed the view that insects that were already rare and localised may well already be individually contributing little to ecosystem processes. In terms of overall ecosystem health, monitoring of invertebrate Guilds (e.g. decomposers and predators) and their function and diversity within an ecosystem may be more important.

TWCL commissioned Lincoln University (Evans, Keesing & Frampton, 1996) to conduct a series of tests of forest sites disturbed by past conventional or coupe logging operations ranging from those felled recently to over 40 years ago. The study involved leaf-litter samples, pitfall traps, foliage beating and malaise trapping. The main findings were:
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  • The abundance of invertebrates depends on the sampling method with leaf-litter samples containing the greatest number of taxonomic orders;
  • Diversity varies widely within areas of similar undisturbed forest;
  • Diversity also varies over harvested sites but not consistently between sampling methods e.g. malaise trapping vs. pitfall traps;
  • There was no evidence that differences in diversity were clearly attributable to forest management;
  • Studies of invertebrates in a 40 year old harvested site and an adjacent control site found similar levels of diversity, except at the canopy level where the modified stand lacked large old trees;
  • No rare or endangered species were identified; and,
  • Many Coleoptera caught on all sites were detrivores and likely to be involved in the decomposition of organic material and nutrient cycling.

Encouraged by these indications from the ‘recovered’ stand, further research was commissioned. This two year project (Evans 1999) compared invertebrate use of undisturbed, naturally disturbed and harvest disturbed (per the proposed regime) forest gaps. The results to date have indicated no significant differences between treatments or controls for diversity indices and carbon : nitrogen ratios.

Results from this research will provide a very strong lead as to any long-term risks from harvesting operations to the overall health of the forest in terms of the more ubiquitous Guilds of invertebrates. The fate of rare and specialised species is likely to be much more a feature of the efficacy of long-term control of predators if such techniques are ever successfully developed.

In the meantime, the management system has been specifically designed to incorporate a “precautionary principle” as follows:
  • Forest structural diversity is maintained inclusive of large old and dead trees;
  • Small canopy gaps are designed to maintain "in forest" environments similar to those of natural forest;
  • Defective woody material is retained on site as "coarse woody debris" to protect invertebrate habitat function;
  • Aerial harvest protects soil litter layers from disturbance; and,
  • Harvest is spatially and temporally separated to ensure constant habitat connectivity and prolonged recovery periods.
Thus under selection systems, impacts of harvesting upon invertebrates can be minimised.
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