Plantation forestry is a significant land-use activity and industry in New Zealand. It is a major contributor to our gross domestic product and provides employment for many New Zealanders. Forestry plays a vital role in climate change mitigation via carbon sequestration, and brings about a range of environmental benefits, such as erosion control.
There are, however, aspects of plantation forestry that need to be carefully managed to avoid potential adverse effects on the environment generated by forestry activities. In particular, the harvesting phase of forestry carries a heightened risk of environmental impacts, such as sedimentation.
The nature of plantation forestry means there are extended periods of limited land-use activity (while trees are maturing), interspersed with periods of intense management activity, relating to the establishment, pruning and harvesting phases. The techniques and physical inputs required during these phases are influenced by New Zealand’s varied soils, water bodies, biodiversity and climatic conditions.
Plantation forestry, like many land uses, is largely regulated by provisions in regional council and territorial authority plans, which are developed as a requirement under the Resource Management Act 1991 (RMA). Local authority plans currently have a varied approach to managing forestry. This inconsistency can cause problems for those in the forestry sector who operate across different regional and district jurisdictions, and across diverse landscapes and environments. The inconsistency within the current planning framework creates uncertainty for the forestry sector and potentially influences costs for, and investment in, the industry.
Given the importance of the forestry sector to the country, this discussion document, including the proposed national environmental standard (NES), aims to ensure that planning controls for plantation forestry are nationally consistent, while ensuring the appropriate management and protection of natural and physical resources.
The Ministry has undertaken a review of a selection of district and regional plans and a sample of resource consent conditions. This was the basis for discussion on options for dealing with the problem. The resulting proposed NES aims to fit within the current framework while providing a pragmatic and balanced approach to plantation forestry activities.
1.2 Purpose of this document
This discussion document has been prepared to:
- help you understand the proposal for an NES, and its potential costs and benefits
- help you prepare questions and feedback
- guide you in making a submission.
The document sets out resource management issues that arise as a result of inconsistency in how plantation forestry activities are currently managed, and considers a variety of options, including an NES, for resolving these issues.
The proposals in this document are equally important to local authorities, because they are intended to support their respective functions under sections 30 and 31 of the RMA. They are also relevant to those interested in plantation forestry activities, such as iwi, non-government organisations and members of the public.
1.3 Structure of this document
The remainder of this introductory section provides an overview of how environmental standards operate, what they are intended to achieve, and the process the Ministry follows in developing new standards. The section also describes the current management approach and the various plantation forestry activities that could be included in an NES for plantation forestry.
Section 2 describes the problem and outlines the policy objective. Section 3 describes and assesses the available options for achieving the policy objective, and section 4 sets out the preferred option, which is the proposed National Environmental Standard for Plantation Forestry.
Section 5 outlines how the proposed standard could be implemented. Section 6 provides a summary of the preliminary assessment of the costs and benefits of the proposed standard. Finally, section 7 outlines the submission process.
The appendices provide additional information on the legislative framework, planning for plantation forestry, possible approaches for some of the options, an evaluation of the options and the classification of erosion susceptibility. There is also a glossary of the relevant terms used in this document.
Supporting reports not contained in this document
This discussion document is supported by the following technical documents.
Review of 12 Regional Council and 4 Unitary Authority RMA Plan Provisions Relating to Plantation Forestry (Brown & Pemberton Planning Group, 2010a). This report, prepared by an independent consultant for the Ministry for the Environment, provides a summary of the rules and controls relating to plantation forestry in the regional planning documents prepared by 12 regional councils and four unitary councils under the RMA.
Review of 23 District Council RMA Plan Provisions Relating to Plantation Forestry (Brown & Pemberton Planning Group, 2010b). This report provides a summary of the rules and controls relating to plantation forestry in the district plans prepared by 22 district councils under the RMA. The 22 district councils with the highest plantation forestry hectarage were selected for the review.
Preliminary Cost–Benefit Analysis of the Proposed NES for Plantation Forestry (Covec, 2010). This report, prepared by an independent consultant for the Ministry for the Environment, is the preliminary cost–benefit analysis of the proposed National Environmental Standard for Plantation Forestry. A summary of the report’s findings is contained in section 6 of this document. The full report is available on our website at http://mfe-refresh-upgdtest/publications/rma/preliminary-cost-benefit-analysis-proposed-nes-plantation-forestry.
1.4 What is a national environmental standard?
National environmental standards (NES) are legally enforceable regulations made under sections 43 to 44 of the RMA. Standards can be numerical limits, narrative statements, or methodologies that are in a legally enforceable form. These may include standards relating to the use and subdivision of land, the discharge of contaminants, or noise. Standards cannot contain guidance material, although the Ministry has produced users’ guides to assist those working with NES. A standard can also indicate whether there is a requirement for a resource consent to be notified.
- prohibit or allow an activity, or state that an activity is permitted
- specify that a resource consent is required, the classes of activity (controlled, restricted discretionary, discretionary or non-complying) and the matters over which control is reserved or discretion is restricted
- restrict the making of a rule or the granting of a resource consent to matters specified in the standard
- require a person to obtain a certificate from a specified person, stating that an activity complies with a term or condition imposed by an NES.
1.5 The process for developing national environmental standards
An outline of the process for developing an NES is shown in figure 1. As part of the scoping process, a reference group was formed to investigate the possibility of an NES. The reference group included officials from central and local government, the forestry sector, and other interest groups such as iwi representatives.
Further detailed analysis was completed with representatives from local government, the forestry sector, Crown research institutes and private consultants. This discussion document, the final outcome of the scoping process, forms part of the submission process.
The process for developing an NES differs from the statutory plan and resource consent processes as there are no express requirements for hearings, and no appeal provisions or First Schedule consultations. The RMA does require the Minister for the Environment to provide an opportunity for the public and iwi authorities to comment on the proposed subject matter of the standard. The RMA also requires the Minister to give reasons for considering the standard is consistent with the purpose of the Act.
The submission period is your opportunity to make a submission on the proposed standard. A six-week submission period is provided to enable any formal approval or ratification of submissions that is required by councils, committees or boards. During this time the Ministry will hold workshops around the country to make presentations and answer questions about the proposal. Details on how to make a submission are given in section 7.
To help you formulate a submission, questions are posed throughout the document on aspects of the proposed standard. However, you are welcome to provide feedback on any aspect of the proposed NES, as well as other options.
If the Minister recommends an NES following consultation on this document, a regulatory impact assessmentFootnote 1 will be required. This discussion document contains, and invites comment on, the substantive elements of a regulatory impact assessment.
At the end of the submission process, the Ministry for the Environment will prepare a report and recommendations on the proposed subject matter of any standard, along with a formal evaluation of the alternatives, costs and benefits under section 32 of the RMA. The report and recommendations must be publicly notified. The Minister will then consider the report and recommendations and the section 32 evaluation before deciding whether to recommend to the Governor-General that the NES be made by order in council.
Figure 1: The process for developing a national environmental standard
The scope of a national environmental standard is first discussed informally with stakeholders. A discussion document is then prepared and approved by Cabinet prior to its release for the purpose of public consultation. Following public notification, and a six-week submissions period, the formal public phase of the development of a standard is completed.
The submissions received are analysed, and a summary is reported to the Minister for the Environment. Also submitted to the Minister are the Ministry’s recommendations on the national environmental standard proposal, a Section 32 RMA cost-benefit analysis, and a Regulatory Impact Assessment. The Minister consults his colleagues, a regulation is drafted and if approved by Cabinet, the reports and recommendations are released and the standard is promulgated.
1.6 Plantation forestry in the context of environmental management and the RMA
The scope of the proposal set out in this document is limited to eight plantation forestry activities associated with the establishment of forests and the subsequent harvesting of trees.
In order to assess and comment on this proposal, it is important to understand the wider context of current environmental management and the RMA. This section describes the management framework for plantation forestry by:
- highlighting the economic and environmental outcomes of plantation forestry
- discussing the importance of local and regional decision-making
- outlining the current process for managing plantation forestry under the RMA, including the role of local and central government.
1.6.1 Plantation forestry in New Zealand
Plantation forests are widespread in New Zealand and have important economic and environmental benefits for the country, including:
- being a key contributor to our economy in terms of exports and employment
- being a supplier of a renewable resource to local and international markets
- playing a vital role in carbon sequestration for the country and our obligations under the Kyoto Protocol targets, including being a key player in the New Zealand Emissions Trading Scheme
- providing environmental benefits such as stabilisation of marginal land or land susceptible to erosion.
The environmental benefits of forestry plantings are described in more detail in section 1.7. Section 2.1 and Appendix 2 discuss the role of plantation forestry in New Zealand, including its contribution to climate change mitigation and the Emissions Trading Scheme.
However, forestry is an intensive land use, and the activity does have environmental effects. It has a long timeframe and effects are predominantly concentrated around the harvesting and earthworks phases of the operations cycle (after 25 years plus of growth). Ideally, the environmental effects that may arise out of harvesting a plantation forest will be considered and addressed at the time the forest is planted.
Some of the detrimental effects of forestry (eg, the clearance of indigenous forests) have reduced due to the introduction of national agreements, Acts and industry-led codes to prevent further clearance of natural indigenous forests and improve practice. See Appendix 1 for more detail on controls.
The nature and degree of adverse environmental effects depend on a number of factors, including site features, machinery used and techniques employed. Potential effects on the environment can include sedimentation of water bodies and slope instability. More detail about the adverse environmental effects of individual plantation forestry activities and current management is given in section 1.7.
1.6.2 Management of plantation forests and the RMA
The RMA sets the regulatory framework for land-use management in New Zealand, and provides for the preparation of plans and rules by regional councils and territorial authorities. The intent of the regulatory framework is to address the adverse effects of land-use activities and promote the sustainable management of New Zealand’s natural and physical resources (see Appendix 1 for more detail about the RMA and relevant legislation).
Plantation forestry is one of New Zealand’s major land-use activities, covering 6.6 per cent of the nation’s land area. As with other land-use activities (such as cropping, dairying and horticulture), forestry has the potential to cause disturbance to water bodies, soil conditions and ecosystems. In giving effect to the RMA, local authorities have requirements to manage the effects of land-use activities within their region or district. The role of local authorities is outlined below in section 1.6.4.
Local authority plans may contain specific rules relating to plantation management, or more general provisions on activities such as the construction of culverts in rural land areas. Plan rules are developed via a statutory process involving consultation and community involvement, including input from iwi authorities and sector groups, such as the forestry industry. The plan development process, including submission and hearing processes, can take several years to complete.
Regional and district plan rules establish whether resource consent is required for plantation forestry activities. Rules for plantation forestry vary across New Zealand as a result of the plan development process. Some plans may have a permissive approach to plantation forestry and consent is not required, while other councils apply more restrictive controls requiring resource consent for certain activities. An explanation of the different activity types is given in section 4.1. The terms and conditions of consent can vary significantly around the country because they are determined by local factors such as habitats of indigenous species or geology.
1.6.3 The importance of local and regional decision-making
It is difficult to create an all-encompassing, entirely consistent national framework for plantation forestry due to the wide variety of receiving environments around the country. Adequately recognising and protecting every receiving environment is extremely difficult at a national level. For this reason it is important to retain a degree of local and regional decision-making. This issue is discussed further in section 2.3.
1.6.4 Role of local government
New Zealand’s local government agencies have responsibility for the regulatory management of plantation forestry within their areas. The specific functions of regional councils, unitary authorities and territorial authorities are outlined under sections 30 and 31 of the RMA, but following is a brief overview.
- Regional councils
There are 16 regional councils, including four unitary authorities. They are responsible for, among other things, controlling the use of land for the purpose of soil conservation and enhancing water quality, maintaining the quality of water, maintaining and enhancing ecosystems, avoiding and mitigating natural hazards, and managing hazardous substances. Regional councils are required to prepare regional policy statements and may prepare regional plans, which may include provisions for managing plantation forestry.
- Territorial authorities
There are 73 district and city councils, which have responsibilities to control the effects of land use (including hazardous substances, natural hazards and indigenous biodiversity), noise and the effects of activities on the surfaces of lakes and rivers. Territorial authorities prepare district plans and issue resource consents that may include provisions controlling plantation forestry activities.
1.6.5 Role of central government
The principal role played by central government in forestry management is at the policy formation, market access and infrastructure levels. The government negotiates access arrangements with our trading partners, formulates the regulatory framework for resource management, invests in biosecurity and biodiversity protection, and provides funding for education, science, statistics collection and infrastructure development. Following are some of the key central government agencies’ roles in plantation forestry.
- Department of Conservation (DOC)
DOC is charged with conserving the natural and historical heritage of New Zealand. There are various pieces of legislation that establish the principles for managing land, including the Conservation Act, National Parks Act, Wildlife Act and Reserves Act. DOC’s core functions include managing and preserving natural and historical resources while advocating and promoting conservation. DOC manages, for conservation, approximately 5 million hectares of indigenous forest (78 per cent of all indigenous forests in New Zealand) and limited areas of exotic plantation forest.
- Ministry for the Environment
The Ministry for the Environment is the Government’s principal adviser on the environment and on international matters that affect the environment. The Ministry provides national direction on the environment through standards, policy statements and strategies.
- Ministry of Agriculture and Forestry (MAF)
MAF is the Government’s primary adviser on the economic and environmental performance of the forestry sector. MAF also leads New Zealand’s biosecurity system and has lead roles in international forestry matters.
- Ministry of Economic Development (MED)
MED’s role is to foster economic development and prosperity, which includes helping New Zealand firms use environmental integrity for economic benefit.
1.7 Plantation forestry activities and associated effects
The typical plantation forestry cycle has a lengthy timeframe, covering 25–50 years from planting to harvesting depending on tree species, climate and soil. During this period some plantation forestry activities (as illustrated in figure 2) require careful management due to their intensive nature and the potential sensitivity of the environments in which they are carried out.
Figure 2 shows the main plantation forestry activities and environmental effects. The diagram depicts a plantation forestry setting with the various stages of the forestry operations cycle and some of the associated effects of these activities. All are numbered as follows:
- Water quality testing
A forestry crew member is taking a water quality sample downstream from plantation forestry activities
- Culvert and fish passage
A stream crossing culvert with fish passage
- Riparian setback
A buffer area between the stream and forestry activities that is vegetated with natives.
A forestry crew member planting plantation forestry seedlings on a site following harvesting of a previous crop. This is evident by the presence of tree stumps and debris.
A forestry crew member is using a ladder to climb a tree and trim the lower limbs off plantation trees.
Two planners are standing by the road planning forestry operations.
A pile of slash (or woody debris from harvesting activities).
- Land preparation
A digger is preparing the land in preparation for planting.
- Earthworks (road construction)
A roller prepares a road for access to the forest.
- Sediment control (silt pond)
A small pond collects stormwater runoff and sediment before it enters the waterway.
A section of land beneath the road is starting to erode away.
Forests of young plantation trees are growing.
A digger is extracting rock from a forest quarry.
- Harvesting (cable hauling)
A large machine (cable hauler) is used for extracting harvesting trees on steep terrain.
A flat area of terrain where logs are stacked for loading into trucks.
A forestry crew member is thinning a more mature forest by cutting down a tree
- Wilding tree
A contractor is removing a plantation forestry tree that has starting growing in a sheep paddock adjoining a forest.
- Indigenous forest remnant
A section of indigenous forest remains in the area adjacent to the plantation forest.
- Archaeological site
An archaeological site located near the road and stream is unplanted.
Following is a brief description of the main plantation forestry activities.
1.7.1 Land preparation, including mechanical land preparation
Land preparation is usually carried out prior to afforestation or replanting (generally after harvesting). Mechanical land preparation addresses site factors such as poor drainage, frost sensitivity, weed competition, heavy slash deposits, and compacted or naturally dense soil. Failure to prepare the land may lead to limited tree growth or crop mortality.
There are several types of mechanical land preparation, including:
- mechanical cultivation (ripping and/or mounding) and spot cultivation to improve the physical condition of the soil
- mechanical raking, mulching, windrowing and blading, to clear residual slash and create planting sites
- roller crushing of weeds or woody debris to prepare sites for planting.
Some land preparation activities may use heavy machinery, which, if not operated correctly, can cause adverse environmental effects. These effects may include soil erosion, and impacts on habitats, natural character, cultural sites and water quality due to sediment run-off to water bodies.
As observed in the Brown and Pemberton plan reviews (2010a, 2010b), land preparation is generally currently managed through regional plan permitted activity rules with associated conditions, including slope thresholds and setback distances. It also falls within general rules for soil disturbance, or as a district plan permitted activity as part of plantation forestry activities.
1.7.2 Afforestation and replanting
Afforestation includes all new forest planting activities, while replanting covers the planting of sites following harvesting of a previous crop. Planting is usually done manually, although where site conditions permit (low gradient, level terrain), mechanical tree planters may be used.
Establishing plantation forests can have many environmental benefits. Prior to harvest, forests can help mitigate the effects of climate change (further described in section 2.1.2), and can also have localised benefits including:
- the maintenance of water quality through providing shade, riparian cover and lower nutrient regimes than other productive land uses
- amelioration of peak flood flows during high rainfall events
- control of sedimentation in water bodies
- control of soil erosion: about 10 per cent of New Zealand is classed as severely erodible land and conversion of erodible pasture land to plantation forestry is an effective method for controlling erosion (Ministry for the Environment, 2007).
Case study: Afforestation of erodible land in the East Cape
New Zealand has a large amount of land at risk from accelerated erosion. In particular, the East Cape region has some of the most erodible land in the world (Hammond, 1995). Severe erosion in the region – including large-scale gully erosion, earth-flow erosion and deep-seated slumps – causes long-term damage to the productivity of rural land and lowers water quality from heavy sedimentation (MAF, nd).
Afforestation is one method used to prevent accelerated erosion. It is effective because it reduces soil water levels and binds the soil together with roots (Hammond, 1995). Overall, water run-off is reduced and erosion is slowed.
The East Coast Forestry Project is an afforestation scheme which aims to encourage sustainable land management on severely eroding lands in the Gisborne District by encouraging the establishment of planted forests as well as the retention of indigenous forest. So far 33,000 hectares have been established in erosion control treatments, and a further 5000 hectares have been approved for establishment over the next few years (MAF, nd).
In addition, plantation forests can provide important recreational values for outdoor pursuits, including mountain and trail biking, walking and hunting.
Some of the possible detrimental effects of afforestation and replanting are:
- wilding tree spread (see section 1.7.8)
- water yield – changes in land use in a catchment from pasture to forestry can alter the amount of water available instream. For example, an analysis of paired catchments showed that annual stream flow yield from pine-forested catchment and native forest was 63 per cent and 73 per cent of that from pasture (Rowe et al, 2002). Afforestation by radiata pine has also been shown to increase the number of zero-flow days in regions where streams are ephemeral, increase the number of times the flow is below a given low flow threshold, and decrease the minimum seven-day low flow (Rowe et al, 2002).
Generally, afforestation and replanting are permitted activities within the main rural zone in district plans, subject to setbacks or shading controls. Regional plans tend to have more controls over afforestation and replanting, including setback distances from water bodies and replanting requirements following harvesting (Brown & Pemberton Planning Group, 2010a, 2010b).
1.7.3 Pruning and thinning to waste
Pruning and thinning to waste are manual operations done from the ground. Machinery (other than chainsaws and workers’ transport) is not usually required.
Whether trees are pruned is determined by what the final felled logs are intended for. About 60 per cent (944,000 hectares) of the New Zealand radiata pine plantation forests is, or is expected to be, pruned to a height of at least 4 metres (MAF, 2009c).
Pruning involves cutting branches from younger trees and is usually carried out in two or three separate operations: at age four to five, at around age six to seven, and (sometimes) at age eight.
Thinning is the cutting down of selected trees in the forest to reduce competition for sunlight, water and soil nutrients, allowing the remaining trees to grow more quickly to maturity. The cut trees are generally left on the ground to break down and return nutrients to the remaining crop. This is often called “thinning to waste”.
Pruning and thinning to waste, if carried out appropriately, can have low environmental effects, limited to minor nuisance issues such as branches dropping onto fences or into water bodies. In order to ensure such activities are carried out with minimal effects, it is necessary to control where pruning materials are deposited. Setbacks from waterways can avoid pruning and thinning debris from entering sensitive environments. Accumulations of branches within water bodies can cause problems, but the size of material means that in most cases it can be easily removed.
Thinning and pruning are generally controlled by territorial authorities and are usually permitted in the general rural zone without specific conditions (Brown & Pemberton Planning Group, 2010a, 2010b).
Harvesting is one of the final steps in the forestry rotation. Harvesting (or logging) usually involves felling trees, extracting them, processing them into logs, and loading the logs onto trucks for delivery to processing plants.
Clear felling is the most common type of harvesting in New Zealand, and involves cutting down the entire stand of trees. Trees are then extracted using methods suited to the topography, forest size, access and potential effects on the environment. Many clear-fell operations take place on steep terrain, where cable hauling is the most common extraction method employed.
Production thinning occurs during a rotation, and is a way of extracting an intermediate crop before final harvesting. The logs from production thinning are much smaller than those from the final crop. Production thinning is usually carried out on easier terrain and utilises ground-based extraction methods (NZFOA, 2007).
The challenges that can be posed by harvesting in difficult terrain can lead to adverse environmental effects if not managed properly. However, unavoidable impacts can be mitigated by best operational practices. Potential adverse environmental effects include:
- indigenous vegetation disturbance (see section 1.7.9)
- slash (woody debris from harvesting operations) (see section 1.7.10)
- soil erosion and sedimentation – poor practice at the time of logging can have a temporary but substantial impact on water quality (Hammond, 1995)
- riparian disturbance (see section 1.7.11).
Harvesting is one of the forestry activities that is currently subject to large variability of rules due to efforts to control the effects outlined above. The Brown & Pemberton Planning Group plan reviews (2010a, 2010b) established that both district and regional plans have rules for harvesting.
In the district plans reviewed, harvesting is generally a permitted activity subject to district-specific conditions, although more restrictive conditions or a different activity status apply in more sensitive areas (eg, riparian margins).
Likewise, harvesting is generally a permitted activity in regional plans, subject to region-specific conditions. More restrictive conditions, or a different activity status, apply for special and/or sensitive environments, such as land susceptible to erosion or specific catchments areas. Rules for slash management are usually part of wider soil disturbance or harvesting conditions (eg, no slash shall enter waterways). In addition, harvesting activities within riparian zones may be subject to both vegetation clearance/harvesting and soil/land disturbance rules in both regional and district plans.
Earthworks activities have the potential to cause significant adverse environmental effects. Earthworks for plantation forestry include the construction and maintenance of access roads, processing areas, landings, tracks, firebreaks and river crossings.
Earthworks usually have significant controls in plans because they can affect soil stability and water quality, and can disturb areas of cultural and environmental significance. Forests are often located on hilly terrain, so earthworks can present operational challenges and may cause adverse environmental effects if not managed properly (NZFOA, 2007).
Road construction and use have the potential to cause the most adverse effects on the environment because they are the greatest source of sediment to water bodies (Maclaren, 1996). Sedimentation can be minimised by practices such as benching roads, sediment traps and revegetation (eg, hydroseeding).
Both regional and district plans have provisions for earthworks and there is considerable variability between rules and conditions. The Brown & Pemberton Planning Group plan reviews (2010a, 2010b) established that generally ‘main rural zone’ earthworks are permitted in district plans, albeit subject to a range of conditions including land restoration, and maximum area/volume/depth. The threshold for conditions varies significantly. Earthworks in special areas such as land susceptible to erosion or significant natural areas are subject to more restrictive conditions and/or activity status. Regional plans apply a similar approach, usually permitting earthworks in general rural zones subject to varied conditions (eg, setback, volume, sediment controls), but applying more restrictive controls in special areas.
1.7.6 River crossings
River crossings are often essential to enable access for harvesting operations. They comprise both permanent and temporary structures that cross rivers and include bridges, culverts, fords, battery culverts, drift decks and log crossings (NZFOA, 2007).
River crossings can cause the following effects:
- sedimentation of the river during construction
- restriction or prevention of fish passage if not constructed properly
- the activation or acceleration of bed erosion by concentrating flows or velocities
- accumulation of debris around culvert openings and bridge abutments which can result in flooding (NZFOA, 2007).
The control of river crossings is largely managed by regional councils, whereas land-based components of river crossings are sometimes controlled at a district level. River crossings are generally permitted, subject to conditions determined by factors such as the type of crossing, flood hazard, fish passage, size and length. The conditions and thresholds between plans vary, and if not met a resource consent is required. Some regions apply more restrictive controls in significant or outstanding landscapes (Brown & Pemberton Planning Group, 2010a, 2010b).
Quarrying refers to the extraction of rock, sand or gravel for the formation of forest roads, and especially those roads needed for transporting logs. Many large forests have dedicated quarries within the forest that may have been in use over numerous rotations. In smaller first-rotation forests, metal may be extracted from suitable sources encountered during road construction, resulting in numerous small extraction sites (referred to as borrow pits).
Quarrying can have similar effects as earthworks activities in relation to soil/slope stability, water quality, landscape, and effects on cultural sites. In addition, there may be noise, vibration, dust and vehicle issues associated with quarrying.
Territorial authorities and regional councils generally control quarrying activities via a resource consent. Some councils permit quarrying up to a maximum volume of earthworks. Regional councils also require a resource consent for large-scale quarrying for plantation forestry purposes (Brown & Pemberton Planning Group, 2010a, 2010b).
1.7.8 Wilding trees
An issue associated with plantation forestry can be natural regeneration or seedling spread from the planted trees occurring in areas not intended for forest production, including indigenous habitats such as tussock grasslands. This is called wilding tree spread, and can be a particular problem in some regions of New Zealand, including the eastern South Island, Central North Island and Coromandel Peninsula. Wilding trees can influence:
- landscape values
- conservation and biodiversity values
- existing land uses
- future land-use options
- catchment hydrology.
Clearing of wilding trees may also be a financial burden for private land owners, local authorities and central government.
The control of wilding trees is usually managed by territorial authorities, which have rules including restrictions on species and the location of afforestation. Regional councils may also deal with wilding pines via regional pest management strategies.
1.7.9 Indigenous vegetation disturbance
Indigenous vegetation disturbance is a component of plantation forestry in terms of:
- disturbance/clearance prior to forests being established (which is now rare, due to regulations and accords)
- vegetation that emerges as understory growth within plantation forests and is disturbed when the forest is harvested
- indigenous forest adjacent to plantation forest
- remnants of indigenous forest within plantation forests that may be disturbed during an forestry activity.
District plans generally protect indigenous vegetation but many provide exemptions; for instance, clearance of vegetation that has grown up on access ways or within the understorey of plantation forests.
The indigenous biodiversity of plantation forests in New Zealand
The importance of some plantation forests as habitat for indigenous biodiversity in New Zealand is now well documented (Seaton et al, 2009). A diverse range of species, including rare and threatened species, have been recorded in the native undergrowth of pines or other exotic plantation tree species (Pawson, 2005; Brockerhoff et al, 2008). The number and type of indigenous species are dependent on plantation age, proximity to indigenous remnants, pruning and thinning history, and a variety of site factors (eg, slope and aspect) (Norton, 1998). Plantation forests have been found to be beneficial for providing habitats, connections/corridors between indigenous forests, and buffers from adjacent non-forested land uses (Pawson, 2005; Brockerhoff et al, 2008).
There are a number of methods used to protect biodiversity within plantation forests. The Wildlife Act 1953 gives legal protection status to native wildlife, but there are also a number of voluntary measures for protection. The Forest Accord, signed in 1991, ensures signatories only establish new forests on non-indigenous forest land but also has provisions for protecting habitats within forests, including remnants and riparian vegetation (Pawson et al, 2010).
Forestry managers are increasingly working to protect rare species within their forests, aided by a number of initiatives led by various organisations, primarily driven by independent certification of sustainable forest management practices. These initiatives include the New Zealand Forest Owners Association’s online threatened species guide, and the publication of Forestry Management Guidelines for North Island Brown Kiwi in Exotic Plantation Forests, led by BNZ Save the Kiwi, the Department of Conservation and Environment Bay of Plenty.
Following is a summary of some of the biodiversity in New Zealand plantation forests.
Some of New Zealand’s threatened bird species find favourable habitats in plantation forests and may utilise plantation stands on a full-time basis, although such instances are limited (Norton, 1998). These species include kiwi, and karearea (falcon) (Kleinpaste, 1990). Other threatened species often utilise plantation forests to supplement food supplies but remain reliant on adjacent natural forest; for example, kaka, kea, kakariki, kokako and kereru (Innes et al, 1991; NZFOA, nd).
The good shelter and high water quality in gullies in plantation forest are ideal habitat for Hochstetter’s frogs. Monitoring in Carter Holt Harvey forests has shown that some frogs survive both wind throw and harvesting, and they have been found in regenerating stands after harvesting (Brockerhoff et al, 2005).
There are records of long-tailed bat colonies in plantation forests (Pawson et al, 2010).
The critically endangered ground beetle Holcaspis brevicula has only ever been recorded from a pine forest at Eyrewell (Canterbury), and not from smaller remnants of nearby kanuka forest. Plantation forests can therefore act as a refuge for indigenous beetle species, especially where indigenous forest is rare (Berndt et al, nd).
The native wood rose (Dactylanthus taylorii) grows in a pine forest in north Taranaki. Iwitahi Orchid Reserve, a few-hectare stand of old-growth Pinus nigra in the Kaingaroa Forest, supports 36 species of native orchid, including the only known North Island population of Chiloglottis valida. A Larch, Corsican and Austrian pine forest near Hanmer Springs is also rich in native orchids.
A total of 202 native (and 70 introduced) plant species were found in 60 small study plots in Rotoehu and Kaingaroa Forests (near Rotorua), Hochstetter Forest (on the West Coast) and Eyrewell Forest (in Canterbury). Another study found 65 indigenous plant species in six plots in the Puruki catchment in the central North Island, seven years after clearfelling a stand originally planted into pasture. Plantations as young as six years may have healthy fern populations, often with levels of diversity similar to adjacent native forest. Tree ferns with densities of up to 2500 per hectare have been found in mature central North Island pine plantations. Although these levels of indigenous species richness are not as high as in native forest, which boasts epiphytes and longer-lived climax species, it is much higher than in pasture, where native plants are normally found at very low levels, if at all.
Plantation forests have been established in areas where threatened plants previously existed. Some threatened species occur in indigenous remnants in plantation forests, such as kaka beak (Clianthus maximus). Some threatened plant species have survived in plantations, such as Pittosporum turneri, Melicytus flexuosus, Carmichaelia kirkii, and Hypolepis dicksonioides. Pine plantations have also created habitat suitable for threatened plant species, such as the orchids (Caladenia atradenia and Calochilus robertsonii), and the wood rose (Dactylanthus taylorii) (Ecroyd, nd).
In general, however, exotic plant species dominate in younger stands in plantations, and indigenous species in older stands. The indigenous flora of plantations comprises mainly indigenous forest-floor and shrub species, which can reach a composition and abundance in older plantations comparable to indigenous forest (Norton, 1998).
Streams and rivers running through plantation forests provide habitats for many native fish. Trees can improve bank stability, help to absorb nutrients from run-off before they reach the stream, and provide shade that controls stream temperature and the growth of nuisance plants. Several endangered species, such as giant kokopu and short-jawed kokopu, have been found in streams running through plantation forests. Mature forests can enhance stream indigenous biodiversity compared with other land uses, and mid-rotation pine forest can have similar stream habitat and biodiversity as indigenous forest.
Slash is the woody debris, such as branches and uprooted stumps, from harvesting and thinning operations. Slash needs to be managed particularly on cutovers and in areas adjacent to waterways. Collapsed slash accumulations can trigger mass movement of soil and debris, causing significant damage (NZFOA, 2007). Slash entering water bodies can have detrimental effects on water flow, water quality, aquatic life, property and infrastructure.
Slash can also be beneficial for returning nutrients to soil and for providing a surface cover that reduces erosion and sediment damage. Research has also shown that some slash left in water bodies can be beneficial to aquatic habitats by providing cover and shade, and regulating water temperature (NZFOA, 2007).
Slash is currently generally managed by regional councils, allowing it as a permitted activity subject to conditions. Conditions include the requirement that no slash enter waterways, or setting a maximum size limit for slash in waterways.
1.7.11 Riparian disturbance
Riparian areas are zones connected with, or immediately adjacent to, the banks of a water body (stream, river, lake or wetland). Riparian areas can form an important buffer, which can mitigate the effects of plantation forestry activities on water bodies.
Environmental effects, such as sedimentation from the disturbance of vegetation and soil in the riparian area (from plantation forestry activities) potentially have a negative impact on water quality and habitats. A riparian setback, where no forestry activity can occur, can be an effective method of reducing adverse effects on the water body.
It is also important to control matters such as the refuelling of vehicles, and weed and algae spread eg, dydimo, within riparian areas to avoid effects on water bodies.
Riparian disturbance is controlled by both territorial authorities and regional councils, as noted in the Brown & Pemberton Planning Group plan reviews (2010a, 2010b). Both usually have controls on riparian disturbance regarding earthworks/soil disturbance or vegetation disturbance. The most common condition for permitted activities is a setback requirement, but thresholds vary depending on factors such as water body type.
Back to footnote reference 1 A regulatory impact assessment (RIA) is a policy tool widely used in OECD countries. An RIA examines and measures the likely benefits, costs and effects of new or changed legislation and regulations. An RIA is used to define problems and to ensure that government action is justified and appropriate.