Arthur Roy Douglas Trewin
Mr. Arthur Roy Douglas
Trewin is the Director/Manager of the Forest
Establishment Quality Assurance based in Rotorua, New
Zealand. His
expertise includes tropical and temperate
plantation establishment systems,
equipment development,
management, training, research and appropriate
technology
development/dissemination and quality assurance: nursery
production of containerized and barerooted seedlings,
cuttings, poles and
stumps. With this expertise, he also
works as a forestry consultant to
numerous forestry
institutions and industries in New Zealand such as the
New Zealand Institute of Forestry, New Zealand Forest
Industries as well
as in other countries such as
Australia, China, Philippines, Papua New Guinea,
Sri
Lanka and others. He has also experience in working with large labor
forces and in aspects of multi-discipline projects:
planning, organization,
environmental impacts, cost
estimating, training, arbitration, health, safety
and
welfare.
Abstract
New Zealand has developed plantation establishment procedures based on over 100 years of practical experience in the planting of radiata pine and other species. 50 years of intensive Pinus radiata D. Don (radiata pine) research on tree breeding, nursery propagation and site preparation has significantly improved initial survivals and growth and the value of final crops. However, problems still occur when nurserymen and field staff fail to follow proven propagation, delivery and planting procedures.
Improved training of managers, supervisors and workers in basic and practical aspects of plantation establishment is needed. Quality Assurance Indicator Plots must be established in all new plantings to help identify and address stock quality deficiencies and weaknesses in out-planting practice. The challenge is to improve the dissemination of appropriate nursery propagation and field establishment techniques to practitioners and, most importantly, to train supervisors and workers in their implementation. Success in establishing high yielding plantations is only possible when stock types and the design of nursery propagation and out-planting systems suit local conditions and all stages of tree stock production and out-planting are integrated, carefully monitored and recorded.
Key Words: bare-root, butt sweep, checklists, containers, contractors, cuttings, establishment, growth problems, handling, indicator plots, integration, mortality, nursery, ordering, packaging, planning, planting, radiata pine, sleeves, small growers, spades, specifications, supervision, targets, toppling, training, transport, windfirmness
The total land area of New Zealand is 27.1 million hectares. Natural forest cover is 6.2 million hectares; logging of this resource has been stopped with the exception of a few very small stands, which are under strict sustained yield management. Early European settlers in New Zealand rapidly converted native forest into pasture for the production of meat and dairy products. This created a demand for fast growing softwoods as indigenous species were slow growing and would require rotations of several hundred years. Many exotic species were planted but Pinus radiata D. Don (radiata pine), a native of California, USA, adapted best to New Zealand conditions.
Records reveal that radiata pine was first planted in New Zealand towards the end of the 19th century, and a few thousand feet were sawn in 1893. Concern at the depletion of the natural forest led to the setting up of an Afforestation Branch of the Department of Lands and Survey in 1896. The first major plantings of exotic softwoods was during the severe depression in the late 1920's when otherwise redundant manpower was employed by the State Forest Service Department. By 1931 over 167 thousand ha of exotic forests, mainly radiata pine, had been planted. There was a lull in planting until 1950.
The plantation resource is now 1.679 million hectares comprising: Pinus radiata D. Don (radiata pine) 1 520 000 ha, Douglas Fir 81 000 ha, Eucalypts 40 000 thousand ha , other species 63 700 ha. Mean annual increment of radiata pine is presently 18.4 cubic meters, with harvest at age 27 years giving a yield of some 500 cubic meters. Genetically improved tree breeds now coming on stream have significantly higher yields (e.g.. 700 to 800 cubic meters per hectare). The resource has been expanding at over 50 000 ha per year since 1992. In 1998 replanting after harvesting was approximately 30 000 ha. Planting of new lands, mostly unproductive farmlands, was 63 000.ha.
The New Zealand State Forest Service, formed in 1920, carried out some research, but it was not until 1947 that the NZ Forest Research Institute was formed. Since then all aspects of establishment; tree breeding, nursery propagation, out-planting and maintenance, have been intensively researched. High quality genetically improved tree stocks out-planted through carefully controlled systems (Trewin and Cullen, 1985), have allowed significant reductions in initial stockings and given much improved final crop yields. Unfortunately, serious growth problems occur when nursery managers and field workers do not follow basic procedures (Mason and Trewin 1987). Forest growers in New Zealand often fail to recognize the critical importance of using only high quality tree stocks, established through carefully controlled systems. Because of this, initial growth is often uneven and tree crops rarely achieve full growth potential. The practical application of quality procedures on large-scale operations is difficult and the ultimate test.
It is essential that forest growers recognize the importance of the establishment phase and put in place cost effective procedures that give assurance of quality at planting. This paper backgrounds establishment in New Zealand. Strengths and weaknesses are discussed and quality assurance procedures recommended.
Weaknesses in establishment systems are often difficult to detect and, after planting, are not easy to correct. Tree crops take a long time to mature so those mistakes made at planting have long term detrimental effects on growth and crop values. Good planning and proven techniques (for stock production and out-planting) are the keys to success.
Until quite recently people ordering bare-rooted and container grown tree stocks in New Zealand rarely visited nurseries to check that sufficiently well grown seedlings or cuttings were available to meet their requirements. Many field men did not feel qualified to judge stock quality and relied on the expertise of nurserymen. Nurserymen for their part rarely invited prospective customers to inspect their crops or visited planting sites to monitor the field performance of their produce. Small growers, often farmers with little forestry experience, ordered stock by mail or telephone, accepting what was offered. Planting was done by contractors, usually recommended by a friend. When post-planting problems such as mortality, poor growth or toppling became evident, it was difficult to trace the cause as few quality control checks had been made to record stock and planting quality.
For best results when establishing plantations, all nursery propagation and field planting operations should be integrated and documented, with quality checks at all stages of nursery propagation and out-planting. Initial field growth should also be monitored in `Quality Assurance Indicator Plots' (Trewin, 2000) to assess the success of establishment procedures and to help identify early growth problems. Quality controllers should use checklists with simple "yes" or "no" boxes. Nursery and field personnel should file the checklists as a part of their nursery and stand records, thereby building up a valuable history of stock propagation and field establishment treatments for future reference.
"Without the use of check lists, it is impossible to accurately control the quality of tree stocks and out-planting procedures"
The aim is to establish a crop of fast growing, uniformly sized trees of good form. This is not always easy as the treatments involved in growing and out-planting tree stocks are difficult to control, particularly on large-scale operations. If problems are to be avoided planning must be good, nursery production and out-planting systems carefully controlled, workers skilled and quality checks frequent. Unfortunately, despite researched and publicized procedures, early growth is often uneven with mortality and wind-firmness poor due to deformed root systems.
"Plantations will have poor initial growth and will be prone to early toppling with consequent butt-sweep unless tree stock is right, its quality good, and handling and planting are carefully controlled".
The following recommendations are based on research results and the practical experience of growers. They are designed to help improve liaison between forest managers, owners, supervisors and workers. For successful development and implementation of quality assurance measures, it is essential that all manual and mechanical operations involved in raising and planting tree stocks are carefully integrated (Trewin & van Dorsser, 1985). To this end, managers must consult nursery and field staff when planning operations and involve them in training new recruits and drawing up quality control prescriptions. Use only high quality tree stocks and out-plant them through monitored systems.
Toppling - A serious problem in New Zealand
New Zealand is a windy country and on fertile sites young trees tend to outgrow the anchoring ability of their roots. The problem can in part be traced to the nursery where the natural anchoring mechanisms of young seedlings, the taproots and laterals, are cut short. This root pruning and wrenching promotes the development of a compact fibrous root system. These treatments condition bare-root seedlings (van Dorsser, 1981) and cuttings (Faulds and Dibley, 1989) to withstand out-planting shock. After planting their fibrous feeding roots take up moisture and nutrition quickly, essential for survival after planting. However, while the preponderance of fibrous feeder roots encourages fast early growth, they do not anchor stems firmly. It can take 3-4 years after planting for large anchoring roots to develop. During this early growth period young trees are likely to develop a lean (topple) in high winds. In recovering an upright stance stems develop butt-sweep which persists and greatly reduces final crop value (Mason & Trewin 1987). Root binding in containers (Menzies and Arnott, 1992)) and distortion of plugs at planting cause similar problems (Trewin, pers. comms.).
" Deformed root systems of poorly planted bareroot or container grown tree stocks are likely to cause stability and survival problems during their growing cycle which significantly reduce crop value and can result in total loss." (Mason and Trewin, 1987).
Most establishment problems arise due to loose control of the many complex operations involved in nursery propagation and out-planting (Trewin and van Dorsser, 1985). In the early 1990's the realization that good profits could be made from growing trees on fertile pasture sites caused a dramatic increase in planting. To meet the demand, nurserymen raised production levels of both bare-rooted and containerized stocks. During this rush period, many untrained workers were employed in the nursery and field. Producing and processing such large stock numbers with inexperienced labour proved difficult. Fast lifting stripped all soil and mycorrhizae from barerooted stocks, and inadequate packaging in flexible bags did not protect stocks from crushing and root breakage during lifting, transport and storage (Trewin, 1981). Some nurseries invested in containerized growing systems as it was felt that they would solve many of the handling and exposure problems experienced with bare-rooted stocks. Reduced disturbance of roots would also allow extension of the winter planting season. However, to make container systems practicable, individual units had to be relatively small. This restricted the size of the plant that could be produced by limiting root development and stem diameter. After planting, the vigorous new growth of small container grown stocks proved more palatable to hares and possums than the larger, more mature, stems of bare-rooted stocks hardened by root-pruning conditioning treatments. Advantages and disadvantages of container and bareroot propagation systems are discussed in an excellent paper (Menzies and Arnott, 1992).
At planting, untrained workers in New Zealand , paid piece rates, are reported to have stuffed up to 3,000 bare-root trees per day into the ground. These uncontrolled out-planting practices cause uneven growth and poor wind-firmness in many plantations. On fertile farm sites top growth tends to outstrip root growth and anchoring ability so that stems are prone to topple in high winds, especially when the roots of bare-root stock is deformed at planting (Mason and Trewin, 1987). Root deformity problems are common when trees are left too long in containers (van Dorsser, 1983). Unfortunately some inexperienced small growers, unaware of the importance of using only good nursery stocks and out-planting systems, continue to experience problems
Large forest growers "in theory" have good control of most operations; they have their own nurseries, permanent professional staff and trained contract labour. Few small growers have such advantages and in most instances depend on outside agencies for advice on site selection, preparation, stock supplies, planting labour and tending. Most nurseries and planting contractors provide good service. However, unless communications and quality checks are regular and efficient, defects are unavoidable.
Extensive trials in New Zealand show that bare-rooted stock is at its most vulnerable to damage and loss of vigour during out-planting (Trewin, 1978) . After the introduction of a fully integrated out-planting system where bare-root stocks were lifted direct from nursery beds into planting boxes, initial survival rates increased dramatically to over 95% on all but the hardest sites (Trewin and Cullen 1985). Equally important was the very significant increase in growth uniformity. With the introduction of improved propagation and out-planting practice, replanting failures the following year became a thing of the past. Good, healthy, fast initial growth also made trees more resilient to pest, disease and competition from weeds. This, in turn, led to lower initial stocking and facilitated the introduction of high cost, genetically improved, tree stocks. All major New Zealand forest companies now plant stocks with high growth and form ratings; the majority use cuttings. However, the rapid growth rates of new tree breeds, especially on nutrient rich ex-pasture sites, have lead to tree stability problems.
The performance of tree stocks and the effectiveness of out-planting systems are judged by field performance. This is easily achieved by establishing Quality Assurance Indicator Plots representing carefully monitored ideal practice, side-by-side with the actual operational practice. Plots are generally established in each planting to cover extremes of exposure or soil conditions, e.g. on sheltered and exposed, or on wet and dry sites. The best way to gauge the quality of tree stocks and identify weaknesses is to monitor the visual health of trees in Indicator Plots at regular intervals after planting (Trewin, 2000).
Producing quality tree stocks is a skilled and difficult operation. Poor seed, shortage of quality cuttings material, adverse weather, and pest and disease attacks can all significantly reduce numbers and quality of plants. Most private nurseries in New Zealand have to anticipate likely stock demands as few foresters do or can give a year's notice of their requirements. Growing tree stocks is therefore a risky business. Even when good stocks are produced there is no assurance that they will be sold. Orders are often cancelled and some forest growers leave ordering to the last moment. Nursery profitability naturally depends on disposing of as many tree stocks as possible. During stock shortages forest growers are prepared to take what is available, during a glut they can afford to be more discerning. New Zealand is a leader in the research and development of bare-root stock growing systems for radiata pine seedlings and cuttings. Vegetative propagation methods have been developed for radiata pine to allow the multiplication of scarce genetic material, particularly control-pollinated seed, and so allow a larger area to be planted with this stock (Menzies and Aimers-Halliday, 1997). The use of containers is increasing in New Zealand, allowing quicker production of planting stock and an extension of the planting season beyond the traditional winter period.
"Growth of bare-rooted and containerized tree stocks must be carefully regulated to avoid overcrowding. Individual trees must be given adequate room to develop. Inadequate spacing, close sowing and small containers cause poor stem diameter/height ratios and poor root development. Thorough testing of a system is essential to ensure that it suits local conditions before going to production levels"
The true test of quality bare-rooted stock is that it survives normal out-planting stress, i.e. re-establishes quickly. Research trials show that the larger the diameter of tree stocks in relation to height the greater the ability to withstand out-planting shock. (Menzies, 1988). NZ Forest Research Institute recommended specifications are:
Note:
Polythene sleeves (not bags) are an efficient and low cost
container for social forestry projects requiring low numbers of large trees.
Different diameter and depth sleeves can be used for different species and the
different sizes to which they are grown. Because sleeves are not closed at the
bottom they are easily cut into required lengths from rolls supplied in flat
tubular form. Most importantly, the large open bottoms promote good drainage for
local soil mixes and allow roots to grow down unimpeded. By moving sleeves
monthly during weeding rounds (one space along sand based nursery beds)
protruding roots are broken, hardening stock for good survival and growth after
planting. Roots bind media together so that it stays intact during planting. A
simple filling apparatus has been designed to facilitate filling and stacking in
beds of a thousand 15cm layflat sleeves per man day (Trewin,
pers.comm.).
The forest personnel responsible for the organisation and control of planting operations must plan at least one year ahead. All too often, supply of quality tree stock from the one nursery is taken for granted. To avoid being stuck with inferior stock when things go wrong (pest and disease attacks, etc) more than one nursery should be approached and advised of likely requirements. When ordering tree stocks it is best to give exact size, nutrient levels, lifting, packaging, storage and transport specifications. To ensure that quality tree stocks are available for future plantings the following procedures are recommended:
Note:
Topping, prior to root pruning, has traditionally been used
to control the height growth of bare-rooted pine and some other stocks.
Exploratory trials indicate that topping, if done early enough before planting
to allow development of fascicles, is a good conditioning treatment. As roots
are not cut, it allows stem and root diameter growth before further conditioning
by lateral root pruning and undercutting of bare-rooted stocks. Box-pruning of
bare-rooted cuttings encourages development of large evenly distributed laterals
and sinkers for increased wind firmness after planting (Trewin, unpub.
data.).
Note:
In a poor nursery growing season one may have to
take a higher percentage of small cuttings with stem diameters >6 mm but
<7.0 mm, to fill quotas. However, unless this stock has very good root
systems planting should be postponed as resulting growth will be poor and
re-supplying the following season costly.
Trials show that out-planting stresses are increased by fast lifting which strips roots of valuable mycorrhizae and by poor packaging which does not protect stock from crushing, root breakage and overheating. When trees are stressed, they burn up the valuable carbohydrate reserves which they will need to survive and re-establish in the field (McCracken, 1981). If stressed, apparently healthy stock may die or fail to establish quickly. For this reason, it is recommended that bare-rooted tree stocks are lifted, root trimmed and packaged direct into planting boxes which in turn are transported in crates, with good ventilation and fitted with shelves for single-layer stacking. This allows free flow of air so that stock can respire freely (Trewin and Cullen, 1985).
Thirty years of selective tree breeding has increased growth rates and improved tree form significantly. Precision sowing in the nursery and new propagation methods have dramatically improved planting stock viability.
Careful lifting, grading, root-trimming, packaging and transport provide planters with high quality vigorous stock. Improved site preparation, planting methods and tending have improved initial growth.
The integration of all these improvements has allowed significant reductions in initial stocking levels from more than 2,500 stems per hectare in the 1960's to less than 1,000 (Trewin and Menzies, 1989). However, the quality of plantations depends on the successful implementation of manual and mechanical operations involved in stock production, outplanting, and site preparation. Small defects in any one part of the system may be of little consequence; however, their cumulative effects can cause poor growth, and even death (Trewin and van Dorsser, 1985). One major company is so confident of establishment success that it has reduced initial stocking of radiata pine to 500 stems/ha.
The aim is to return stock to the ground with roots orientated slightly down and deep for good anchorage and moisture. Lifting a young bareroot tree from the ground and replanting it so that roots are naturally orientated for good growth and anchorage is difficult. In the nursery the anchoring tap-root and laterals are cut short to promote development of fibrous feeder roots and facilitate outplanting. Lifting and handling techniques have been refined to keep stress to a minimum, but good positioning of many fibrous roots at planting is difficult and requires careful supervision of workers.
The removal of long anchoring roots in the nursery, during conditioning and to facilitate root placement at planting, reduces tree stability in the field so that trees are prone to topple in the first 3-4 years (the time taken for good anchoring roots to develop). Twisting of roots at planting aggravates this problem, particularly in heavy soils with poor drainage where root development tends to be slow.
In New Zealand spade planting is most common and a "Lever & Lock" hole opening technique is recommended. After replacing loose soil around barerooted stock a "Positive-Pull-Up"(PPU) to straighten roots and orientate them down slightly is given (Trewin & Cullen, 1985. Good supervision of planters with penalties for poor and rewards for good planting, is essential. A pass book in which supervisors record the names of planters and the quality of work has proved effective in maintaining standards.
"The weakest link in the radiata pine plantation establishment system is the planting operation. As planter payment is based on the numbers of trees planted, the tendency is to rush the job. Supervisors and planters need frequent reminders and adequate checks to ensure that planting quality is good"
It was thought that using containerized tree stocks would eliminate root distortion common when control of bareroot planting was poor. Unfortunately, this is not the case as roots in plugs can easily be bent and squashed at planting (Trewin, pers,. comm.). For successful establishment of container grown radiata pine, any confused roots at the bottom of plugs must be removed, sliced off, before dispatch from the nursery, otherwise they remain bent after planting and anchorage for windfirmness is reduced.. At planting plugs must be carefully positioned deep enough for good moisture in well cultivated soil. Care must be taken not to crush or bend plugs during firming-in as this damage can adversely affect survival and stability. Container grown radiata pine stocks are smaller and because they are not physically conditioned, foliage is more lush and palatable. Therefore, it is essential to eliminate grazing animals prior to planting e.g. rabbits, hares and possums, as they cause much damage. Larger animals are also major pests, they break boundary fences and enter from adjacent areas to graze and kill young trees.
Care and attention required for the delivery of a young tree from the nursery bed to planting in the field can be compared to that required for the delivery of a baby. Fortunately the condition of the baby after birth can be quickly assessed and, if there are problems, remedial action taken. The condition of the tree after planting is not so easily assessed and even if problems are recognised they can rarely be remedied.
Due to the seasonal nature of planting, many nursery and field workers are inexperienced as only a short period of training is possible. Therefore, it is essential that all establishment personnel make it a priority to be in the field to assist in this most critical operation. Unfortunately, many managers leave the supervision to field staff as organizational duties and entering of data in computers take up much of their time. Computers do not plant trees! Office staff should handle problems as the presence of all experienced staff is needed to help with planter supervision. Planting quality checks must be frequent and close behind the planters. By recording the quality of each planter's work against a checklist (Trewin, 2000) faults are easily and quickly traced to individuals and remedied. The standard random quality control plots used by some companies do not trace faults directly to individual workers, who continue to plant badly.
Check lists are essential for control of planting quality
To ensure that all operations run smoothly, check lists are an essential part of quality control procedures. Before tree stocks leave the nursery they should be inspected and dispatch notes signed to acknowledge that trees are to specification. In the field, tree stocks are again checked to see that they meet specifications. During planting operations supervisors inspect stocks regularly to see that they are in good condition and report any deficiencies direct to the nursery. It may be that the trimming of roots to facilitate root placement is not good or that valuable mycorrhizae have been removed by careless lifting. Drying out of roots is a common problem, and watering of nursery beds prior to lifting and/or the application of polymer gels after lifting may be needed to keep roots moist. Fine feeder roots and mycorrhizae, essential for uptake and nutrients after planting, quickly die unless kept moist. Careless handling during planting (e.g. leaving tree containers in direct sunlight), causes stock to overheat and burn up carbohydrate reserves (McCracken, 1981).
"Without the use of check lists it is impossible to accurately assess and control the quality of manual operations"
Note:
Planting contractors and supervisors frequently
claim that their quality control procedures are adequate and that no checklists
or written records of work quality are necessary. When calling for tenders and
drawing up written contracts, managers must stipulate that checklists be
submitted for inclusion in stand records.
When cultivating soils and planting, it is essential that all workers use a standard tool. In New Zealand spades are used for planting bareroot and container tree stocks. Most planters own their own spades, many of which are of different design and size; because of this there is little chance of uniform good planting quality. Some growers do not appreciate the importance of using good spades for deep cultivation and planting. Specialized tools are available for planting container plugs in loose soils; they are not popular in New Zealand as most sites are cultivated with a spade by the planter.
When employing planting contractors it is essential that they are first shown the planting site so that they can assess the difficulty of planting and agree on the most suitable planting tool. Only then can the contractor have sufficient information to tender accurately for the work and meet high standards. In New Zealand the Atlas (flat bladed spade) is most popular for light soils. In heavy clay soils a modified Spears and Jackson trenching type spade is commonly used as the slightly concave blade facilitates freeing of wet soils from the face during digging. The importance of using good tools is stressed.
In hard and stony soils where mechanical cultivation is not possible, it is often more efficient to use one gang of workers to cultivate and another for planting.
Planting target assessment
A reasonable assessment of tree numbers that can be planted properly in a normal 8 hour day can be quickly made. On the site to be planted an experienced worker is asked to plant at a steady rate for 15 minutes. Multiplying the number of trees planted by 24 gives the equivalent of 6 hours continuous hard work and allows for meal breaks, collection of stock etc. during a standard 8 hour day (for increased earnings planters often work longer hours). In friable, machine cultivated soil, an expert New Zealand worker can plant a bareroot tree every 15 seconds, 240 trees/hr, or 1440 in six hours (Trewin & Kirk 1992). The numbers of trees that can be planted varies considerably depending on: soils, slope, old harvest residue, ground preparation, motivation and fitness. In heavy clay soils, where workers have first to cultivate with a spade, planting rates of one tree every 40 seconds reduces the daily target significantly to 540 plants. As payment to contract workers is generally based on numbers planted, good payment incentives must be offered for fault free work.
Because of the seasonal nature of raising and planting tree stocks it is not possible to maintain large, permanent and well trained labour forces. Therefore, each season many new and inexperienced workers have to be recruited and trained. Most training is left to contractors and is "on-the-job". Contract payments are usually based on production so that the higher the numbers of trees processed the greater the financial reward. This encourages fast lifting and planting which damages stock and can cause long term growth and wind-firmness problems. Nursery and field workers need to be trained in fast efficient tree handling techniques that do not damage stocks. While forestry schools and polytechnics do a good job training forestry personnel, it is not possible for them to educate temporary, seasonal employees stationed throughout the country. This has to be left to experienced practitioners who can explain and demonstrate "on-site" the most appropriate techniques.
"For the assistance of trainers at pre-planting workshops good video and illustrated pamphlets are needed and should be supplied by training organizations."
A day is scheduled by the employer, immediately before planting starts, for the training of temporary planting gangs and supervisors. Where nurseries are close to planting sites it should be possible for nurserymen to arrange joint workshops involving nursery and field workers. It is essential that workers understand the basic processes involved in growing trees. A morning session covers research and development using visual training aids, slides, video and diagrams, to educate and impress on workers the importance of their jobs. An afternoon session, visiting the nursery and field, covers all practical operations involved in lifting, handling and planting. Examples of one year old root systems are excavated from Quality Assurance Indicator Plots and surrounding production plantings to check and discuss planting quality (Trewin, 2000). Give workers an illustrated pamphlet showing all stages of correct stock handling (Trewin and Cullen, 1985). Free meals, and an after work social, help establish good worker relations with management.
Good supervision is essential for successful control of the many operations involved in producing high quality tree stocks and out-planting them successfully. The trail of supervision travels down from senior management through forestry staff and supervisors to contractors. Responsibility for each phase of establishment must be clearly defined and allocated to a staff member. A wall chart is a good aid for monitoring tree stock quality and out-planting procedures and should show dates and the person responsible for arranging stock orders, checking quality in the nursery and at the forest. The chart should also show when site preparation and planting contracts are scheduled, and the person responsible. It is best that staff responsible for ordering stocks and field operations draw up their own charts and checklists in consultation with managers. There can then be no confusion as to how and when quality checks are made and who is responsible. Wall charts should also identify those responsible for post-planting checks on growth in QA plots and surrounding plantings (Trewin, 2000). These regular visits are also essential for checks on weed growth and animal damage.
It is essential that Quality Assurance Indicator Plots, representing exact nursery and field prescriptions, are used to check the efficiency of production plantings (Trewin, 2000). Staff responsible for plantings should visit nurseries and personally supervise the lifting/packaging of one or two hundred tree stocks. They then transport the stock to the planting site and supervise the establishment of two, three or more 50 tree plots, depending on the size and variability of the land, with reference to exposed and sheltered positions. Plots are established as soon after production planting as possible. Ten production planted trees from five alternate rows are replaced with 50 Quality Assurance trees. An additional 10 QA trees are planted, five at either end of the QA plot at half spacing, for destructive root form sampling (the extra closed spaced trees help identify plots, should marker stakes be lost). By comparing Indicator Plot performance with side-by-side operational plantings, success of out-planting procedures are assessed. Visual health checks, carried out at 3, 6 and 12 months reveal any establishment problems. Random sampling of a small percentage of root systems (5%), with a photographic record, helps build up knowledge on root growth in relation to container type or bareroot growing methods. One forester using QA Indicator Plots has reported:
"When actual operational establishment of radiata pine is compared side-by-side with potential (ideal) implementation of our prescription techniques for lifting, dispatch, and planting, it is found that first year growth of seedlings established on an operational basis falls short of potential. Loss of potential growth amounts to 2.8 mm in diameter (21% of potential), 15 cm in height (16% of potential and 44% of potential bulk growth). Survival is also down to 92% of potential" survivals."
The following planting season improvements in the culling and handling of stocks raised survivals from 92% to 99% with associated improvements in initial growth "
Although 92% survival, in the past, was considered satisfactory, QA plots have shown that unless survivals are in the high 90's (animal damage excluded), growth losses result. Larger trees soon shade out less vigorous plants causing unevenness in stands.
Even if survivals in Indicator Plots and the surround operational plantings are 100%, it is important to monitor initial health and growth at regular three monthly intervals after planting, or more frequently in the tropics where weed growth can smother young plants within a few weeks after rain. Ideally, animals that damage young trees should be eliminated before planting. This is rarely possible so control methods have to be good. The aim is to achieve good fast and uniform initial growth in plantations as this reduces the cost of weed control and simplifies all subsequent silvicultural operations
Note:
The QA Indicator Plot reported above was in the NZ
Central North Island pumice land where rainfall distribution is good. Had the QA
plot been in a dry area, differences between potential and operational plantings
would likely have been much greater.
In New Zealand with its oceanic climate, radiata pine has outperformed all other species, so research and development has been concentrated on this one species. This has resulted in significant improvements in stock propagation and out-planting procedures. However, there are still weaknesses in the practical aspects of establishment, mainly due to untrained seasonal labour and inadequate quality control procedures. Other countries experience similar difficulties and, in addition, have to deal with many more species and less favorable climates.
The choice of appropriate and cost effective propagation and outplanting systems, and the development and control of quality assurance procedures for their implementation, is a continual challenge for establishment managers.
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