NZJFS - Volume 40 (2010)
The New Zealand Journal of Forestry Science had a biosecurity focus in 2010. Volume 40 included the proceedings of the IUFRO International Forest Biosecurity Conference held in Rotorua, New Zealand from 16 to 20 March 2009. A special supplement to Volume 40 was also published. This supplement contained the proceedings of a biosecurity workshop, held at the Conference on 17 March 2009. This workshop was sponsored by the Organisation for Economic Co-operation and Development (OECD) to explore the different perspectives of scientists, policy makers and forest managers.
Spatial variation in spiral grain: a single stem of Pinus radiata D.DonCown, D. J., Harrington, J., Bourreau, D., Haug, J., & Lee, J.
Cown et al. (pp. 211-224) studied spiral grain in logs from a radiata pine tree. Two methods - disc scribing and laser dot scanning - were used. The results showed that there can be real variation in radial median spiral grain values of up to 4 degrees. Consequently, assessment of spiral grain angles along single radii (as from breast height cores or discs) is not recommended, unless a minimum of two radii can be averaged to compensate for possible tilt in relation to the stem.Published Online - 11 Nov 2010. [1.5 MB] (pdf).A single 18-year-old Pinus radiata D.Don tree was felled and log sections (2.5 m) removed at intervals up the stem for intensive spiral grain measurements. All logs were assessed externally with a laser dot scanner to quantify grain direction at 16 radial positions circumferentially, and subsequently four discs were removed from each log - two representing internodal sections and two close to branch whorls. Grain angles were measured by scribing at each growth ring boundary along 16 radii corresponding to the external measurements.
The study highlighted the degree of variation in grain angles determined using a disc "scribing method" and the log surface grain angles determined using a laser dot scanner. The former method of "point sampling" does not reveal the small-scale (mm) spatial variation quantified by higher intensity sampling such as is possible with dot laser scanning. Both approaches confirmed an average "generic" pattern of within-stem variation in grain angle (i.e. higher values in juvenile wood and at higher levels in the stem) but also quantified the spatial variation radially, circumferentially and longitudinally in a mid-rotation stem.
Average angles increased rapidly over about the first 5 rings from the pith to an average of 6 to 10 degrees and thereafter decreased outwards to the bark at all levels. Circumferentially, grain angles were highly variable and varied by several degrees within a matter of millimetres. The degree of variation recorded here for radiata pine was much greater than had previously been reported for other species and the results highlight the limitations of studies which only examine single radii or widely spaced disc samples. Even the average values around the stem for individual radii were observed to vary by up to 6 degrees, at least partly due to some tilting of the disc with respect to the stem axis. Within individual growth rings, grain angles did not show a strong consistent longitudinal pattern up the stem, apart from an increase from the lowest log to the upper logs. In the sample discs, grain angles above the lowest log were, on average, 2 degrees greater at equivalent growth rings. In this study, the impact of branches and knots was found to be very localised. When discs from within 50 mm of visible branch whorls were analysed, the effect on grain angle was not obvious.
The disc scribing and log laser dot scanning methods were compared and found to give similar grain angle values - the averages were generally within 2 degrees with no obvious bias. Given the documented spatial variation, and the difficulty of referencing "true" grain angles, it is a moot point as to what can be considered a reasonable level of sampling accuracy for a particular study. In the authors' opinion, 2 degrees is a very acceptable level.
The implications for spiral grain sampling were discussed. For comparative purposes, studies of silvicultural and breeding effects require cost-effective sampling. Assessment of spiral grain angles along single radii (as from breast height cores or discs) is not recommended, unless a minimum of two radii can be averaged to compensate for possible tilt in relation to the stem. The current study showed that there can be real variation in radial median values of up to 4 degrees.
Dot laser scanning is the most practical option for assessing log and timber surface grain angles in processing plants, where deviations around knots and branches and due to log sweep can be screened out to reveal important average trends for timber twist prediction.
The spread of the exotic conifer Pseudotsuga menziesii in Austrocedrus chilensis forests and shrublands in northwestern Patagonia, Argentina.Orellana, I.A., & Raffaele, E.
Invasive introduced species are among the most severe threats to biodiversity and the functioning of natural ecosystems.Orellana and Raffaele (pp. 199-209) found that the establishment of the invasive, introduced species Pseudotsuga menziesii (Douglas-fir) was significantly higher in native Austrocedrus chilensis forest than in shrublands of northwestern Patagonia, Argentina.Published Online - 27 Sep 2010. [970.7 KB] (pdf).Invasive introduced species are among the most severe threats to biodiversity and the functioning of natural ecosystems. In this study we analysed whether Pseudotsuga menziesii (Mirb.) Franco is an invader species of two common types of native communities (native Austrocedrus chilensis (D.Don) Pic. Serm. & Bizzarri forests and mixed shrublands) of the subantarctic region of Argentina. We determined the density and the age structures of both P. menziesii and A. chilensis regeneration at the edges of P. menziesii plantations adjacent to native forests of A. chilensis and mixed shrublands. The invasion of P. menziesii was recorded in both types of native communities. In A. chilensis forest, the establishment of P. menziesii was significantly higher than in the shrublands. Also, P. menziesii showed a greater spread than A. chilensis inside and outside the plantations. The increased abundance of P. menziesii plantations, in addition to its invasive characteristics could lead to the replacement of native communities at a regional scale in the long or medium term.
Genetic improvement of stiffness of radiata pine: synthesis of results from acoustic assessments.Kumar, S., & Burdon, R. D.
Kumar and Burdon (pp.185-197) reviewed results from various studies on genetic parameters of stiffness of radiata pine and evaluated potential for simultaneous genetic improvement of quantity and quality of structural timber. They concluded that a mix of tools, namely genetics, siting, silviculture and segregation, would need to be adopted to maximise quality and quantity of structural grade timber from radiata pine plantations in New Zealand.Published Online - 27 Sep 2010. [860.0 KB] (pdf).The main objectives of this study were to: (i) review results from various published and unpublished studies on genetic parameters of stiffness of Pinus radiata D.Don (radiata pine); and (ii) evaluate potential for simultaneous genetic improvement of quantity and quality of structural timber. Standing-tree acoustic velocity data were first converted to average butt-log timber stiffness (Log1MOE), and were used for genetic parameter estimation and genetic gain predictions. Results from a number of different-aged seedlings and clonal trials were summarised.
Average Log1MOE varied from 5.4 to 9.1 GPa with phenotypic coefficients of variation ranging from 11 to 16%. On average, the additive genetic control of Log1MOE in the trials aged 9 - 12 years appeared moderate (h2 0.35). Estimated between-sites genetic correlations generally ranged from 0.60 to 0.90, indicating relatively low genotype-by-environment interaction. Results from trials aged 11 - 15 years indicated that Log1MOE could be increased on average by about 11% when the top 5% of families are selected. This level of improvement would only push the average corewood MOE of the production population to about 7.0 GPa. Indications are that simultaneous genetic gains for MOE and timber volume should not be seriously affected by a negative genetic correlation. A mix of tools, namely genetics, siting, silviculture and segregation, would need to be adopted to maximise quality and quantity of structural grade timber from radiata pine plantations in New Zealand.
Correlated response of pulpwood profit traits following differential fertilisation of a Eucalyptus nitens clonal trial.Stackpole, D. J., Joyce, K., Potts, B. M., & Harwood, C. E.
Stackpole et al. (pp. 173-183) examined the response of pulpwood profit traits following differential fertilisation of a Eucalyptus nitens clonal trial. Pulpwood production per hectare indicated that: (i) the choice of germplasm had a much larger effect on plantation profitability than did the starter fertiliser application; and (ii) the gain in pulp production due to starter phosphorus application could be over-estimated by up to 0.6 t/ha or 20% per 12 year rotation due to adverse changes in wood properties.Published Online - 16 Sep 2010. [802.5 KB] (pdf).Silvicultural treatments that are aimed at increasing plantation growth rate may also impact directly or indirectly on wood properties. We examined this impact in a fertiliser × clone trial in northwestern Tasmania, Australia. Nitrogen (N) and phosphorus (P) fertilisers were applied at planting to three Eucalyptus nitens (Deane et Maiden) Maiden clones and one F1hybrid clone of E. nitens and E. globulus Labill. in a factorial design with each clone exposed to two levels of nitrogen (0 and 23 kg N/ha) and two levels of phosphorus (0 and 21 kg P/ha) spot-applied close to each seedling. The trial comprised four replicates per treatment with 5 × 5 tree clonal plots. Height was measured at ages one and two years, and diameter at breast height over bark at age 11 years. Increment cores at breast height were obtained from one fast- and one slow-growing ramet within each clonal plot to determine corewood basic density, near infrared-predicted kraft pulp yield, cellulose content, and extractives content. No significant interactions among main treatments were detected for any of the growth- or wood-property traits. Nitrogen application increased cellulose content (p < 0.05). Phosphorus application significantly increased diameter (p < 0.01), but resulted in lower wood density (p < 0.001). Within clonal plots, large trees had lower wood density (p <
Potential applications of Randomised Graph Sampling to invasive species surveillance and monitoring.Ducey, M. J., & O'Brien, K. M.
Accuracy and reliability demand that surveillance and monitoring of invasive species be statistically sound. However, realistic budget constraints demand that those activities be efficient and feasible. This means that it may be necessary to draw inferences from a sample rather than a complete census. In this paper, Ducey and O'Brien (pp. 161-171) describe a type of sampling called Randomised Graph Sampling and illustrate this approach using simplified examples.Published Online - 14 Sep 2010. [953.6 KB] (pdf).Many invasive plants and animals disperse preferentially through linear networks in the landscape, including road networks, riparian corridors, and power transmission lines. Unless the network of interest is small, or the budget for surveillance is large, it may be necessary to draw inferences from a sample rather than a complete census on the network. Desired features of a surveillance system to detect and quantify invasion include: (1) the ability to make unbiased statements about the spatial extent of invasion, the abundance of the invading organism, and the degree of impact; (2) the ability to quantify the uncertainty associated with those statements; (3) the ability to sample by moving within the network in a reasonable fashion, and with little wasted non-measurement time; and (4) the ability to incorporate auxiliary information (such as remotely sensed data, ecological models, or expert opinion) to direct sampling where it will be most fruitful. Randomised graph sampling (RGS) has all of these attributes. The network of interest (such as a road network) is recomposed into a graph, consisting of vertices (such as road intersections) and edges (such as road segments connecting nodes). The vertices and edges are used to construct paths representing reasonable sampling routes through the network; these paths are then sampled, potentially with unequal probability. Randomised graph sampling is unbiased, and the incorporation of auxiliary information can dramatically reduce sample variances. We illustrate RGS using simplified examples, and a survey of Polygonum cuspidatum (Siebold & Zucc.) within a high-priority conservation region in southern Maine, USA.
Herbicide screening trial to control dormant wilding Pinus contorta, P. mugo and Pseudotsuga menziesii during winter.Gous, S. F., Watt, M. S., Richardson, B., & Kimberley, M. O.
Wilding conifers are a serious threat to conservation land in New Zealand. The current herbicide (diquat) treatment is not very effective, and has an adverse effect on non-target species. Gous et al. (pp. 153-159) compared this herbicide treatment with eight other herbicide treatments to evaluate if there are more effective alternative herbicide treatments to control three wilding conifer species. Treatments were compared using a pot-based trial conducted during winter. Overall, the most effective treatment contained two selective systemic herbicides, triclopyr, and picloram, which caused a minimum of 98% damage for all three species.Published Online - 13 Sep 2010. [3.5 MB] (pdf).In New Zealand, wilding conifers threaten over 210 000 hectares of land administered by the Department of Conservation in the South Island alone. Currently, the contact herbicide diquat is applied aerially at a rate of 15 L/ha in 400 L of water to control Pinus contorta (Dougl.). As this treatment is not very effective, and has an adverse effect on non-target species, the objective of this study was to evaluate if there are more effective alternative herbicide treatments to control not only P. contorta, but also Pinus mugo (Turra) and Pseudotsuga menziesii (Mirb.) Franco.
The currently operational herbicide diquat treatment was compared with a second diquat-only treatment at the same 15 L/ha rate but applied in 150 L total volume. Seven treatments using alternative herbicides were also studied. All treatments were applied during winter in a pot-based trial.
Analysis of variance showed highly significant differences between herbicide treatments (F8,32 = 53.3, p<0.0001), between species (F2,72 =71.8, p<0.0001) and also detected a significant interaction between species and treatment (F16,72 = 9.8, p<0.0001). When averaged across all treatments, damage to Pinus contorta and Pseudotsuga menziesii was 84%, which significantly exceeded that to Pinus mugo, at 68%. Due to the significant interaction, each species was also analysed individually.
Overall, the most effective treatment contained two selective systemic herbicides, triclopyr, and picloram, which caused a minimum of 98% damage for all species. Results indicate that treatments containing the non-selective systemic herbicide glyphosate controlled Pinus contorta and Pseudotsuga menziesii very effectively. Pinus mugo, however, was only moderately affected by these treatments. Treatments containing diquat were generally more effective than those containg glyphosate but less effective than treatments containing triclopyr/picloram.
Implications of climate change for forests, vegetation and carbon in Australia.Singh, S., Davey, S., & Cole, M.
Singh et al. (pp.141-152) discuss how future management of sustainable and productive forests in Australia requires realistic evaluation of the impacts of climate change.Published Online - 5 Aug 2010. [2.1 MB] (pdf).The Intergovernmental Panel on Climate Change predicts that the level of threats to forests and vegetation will increase in the 21st century. Rising temperatures, drought, forest fires, heavy rains, humidity and cyclones will render forests and vegetation more prone to many threats, including pests and diseases. Pests and diseases adapted to warmer conditions would extend their distribution to the southern direction and higher elevations in Australia. Drought stressed plants may become more susceptible to existing pests and diseases, including bark beetles and Phytophthora spp. A range of exotic pests and diseases, if introduced, may cause widespread damage in Australia. Managing sustainable productivity inter alia requires realistic evaluation of impacts of climate change on potential threats to forests and the ecosystem services they provide, including as a carbon sink. Such evaluations of threats will assist future planning including prudent use of silvicultural practices to mitigate possible threats. Climate models can enable: better understanding of future threats to Australia's forests and vegetation and related ecosystem services; and better preparedness to safeguard Australia's natural resources in a changing climate. Forest management systems and plans can incorporate measures for mitigating the changing risks associated with pests, diseases, weeds, drought and fire. They can include contingency plans for the emergency salvage of damaged or dead standing timber to prevent damaged forest stands from becoming a source of greenhouse gas emissions.
Interceptions and incursions of exotic Sirex species and other siricids (Hymenoptera: Siricidae).Burnip, G. M., Voice, D., & Brockerhoff, E. G.
Burnip et al. (pp. 133-140) examine and discuss historical records of siricid interceptions at New Zealand's border, in relation to patterns of interception records over time and the key species intercepted. They also present two recent and noteworthy siricid incursions as case studies, with an emphasis on the science used in decision support.Published Online - 19 Jul 2010. [746.9 KB] (pdf).The family Siricidae has more than 100 species in about 11 genera. Nearly all species are native to the Northern Hemisphere although there is an endemic genus (Afrotremex) in southern Africa. Collectively they are known as woodwasps or horntails. All siricids are wood borers and several species are forestry pests to varying degrees. New Zealand has a single species of siricid woodwasp, Sirex noctilio F., thought to have been accidentally introduced around 1900. Two recent and noteworthy siricid incursions are presented as case studies, with an emphasis on the science used in decision support. The first case study describes the advantages of using morphological and molecular diagnostic approaches in combination. This case resulted in the first published host record association between S. noctilio and Amylostereum areolatum (Chaillet ex Fr.) Boidin in Cedrus atlantica (Endl.) Manetti. The second case study reports the application of published life cycle developmental data to assess establishment risk, and profiles the entry of Sirex juvencus (L.) into New Zealand within timber stamped with the International Standards for Phytosanitary Measures (ISPM) 15 mark, and the Ministry of Agriculture and Forestry Biosecurity New Zealand's actions to mitigate this high-risk pathway. Historical records of siricid interceptions at New Zealand's border are examined and discussed, in relation to patterns of interception records over time and the key species intercepted.
Emerald Ash Borer First Detector: a volunteer early detection programme.Gupta, A.
Gupta (pp. 123-132) explains the details and benefits of the Emerald Ash Borer First Detectors Programme, which is helping to identify new infestations of emerald ash borer in Minnesota.Published Online - 8 Jul 2010. [2.2 MB] (pdf).The emerald ash borer (Agrilus planipennis Fairmaire) is a serious forest pest in the United States and its range is expanding. In June 2008, emerald ash borer was confirmed in six US states. As of July 2009, it was confirmed in 13 American states, including Minnesota. Detecting its presence early in an infestation will allow forest managers more management options. University of Minnesota Extension partnered with Minnesota Department of Agriculture, Minnesota Department of Natural Resources, and the United States Department of Agriculture Federal National Plant Diagnostic Network, to develop the Emerald Ash Borer First Detectors Programme to help identify the first incidence of emerald ash borer in Minnesota and each Minnesota county. First Detector volunteers are one of the first lines of defence against the establishment of emerald ash borer in Minnesota by helping to identify the first occurrence of emerald ash borer. They can visit properties, collect and safely mail samples to the Minnesota Department of Agriculture, collect seed for genetic conservation, and help educate and inform the public about emerald ash borer. In 2008, 180 First Detector volunteers state-wide were trained in six full-day workshops to identify emerald ash borer and the signs and symptoms of an emerald ash borer infestation. In 2009, the First Detector programme was broadened to include three additional forest pests: gypsy moth (Lymantria dispar Linnaeus), Asian longhorned-beetle (Anoplophora glabripennis Motschulsky), and Sirex woodwasp (Sirex noctilio Fabricius). In 2009, programme organisers trained 233 individuals in the Forest Pest First Detector programme.
Conservation and management of potentially resistant tree germplasm: a key but easily neglected part of a robust biosecurity strategy.Burdon, R. D.
Burdon (pp. 115-122) argues that the availability of pest-resistant genetic material is a critical part of a robust biosecurity strategy yet stringent quarantine and general regulatory restrictions greatly hinder the importation of fresh germplasm into New Zealand. Commitment from various parties will be required to achieve a solution to this issue.Published Online - 7 Jul 2010. [756.8 KB] (pdf).A comprehensive biosecurity strategy must contain due provision for living with uncontained incursions of injurious organisms. Collectively termed pests, these organisms include fungal pathogens and certain insects. Provision for living with such pests includes availability of genetic material that offers pest resistance. For that, genetic diversity is a widely agreed requirement, especially as pests can appear with no prior record of being significant.
While breeding for resistance is a rear line of defence, it poses a special need for forward preparation. Maintaining and structuring the appropriate genetic diversity, however, can be very challenging. Genetic improvement of preferred species can accentuate their preferred status, making it even less attractive to retain stocks of potential back-up species. And in the preferred species, genetic improvement can escalate the opportunity costs of retaining unimproved or less-improved material containing much more genetic diversity than the main commercial crops. Also, importing fresh germplasm poses some border security risks. Furthermore, globalisation compounds certain institutional factors that militate against retaining genetic diversity.
These issues particularly affect countries where commercial forestry depends on exotics. New Zealand is a notable example. About 90% of its commercial forest estate is in one greatly preferred, exotic species, Pinus radiata (D.Don). This species is the subject of intensive genetic improvement, which has very strong industry uptake, while it is widely grown on sites of relatively high disease hazard. Stringent quarantine and general regulatory restrictions greatly hinder the importation of fresh germplasm. Other complications include: global interests and strong international risk spread of foreign forest owners; and rapid changes in forest ownership and management. Unfortunately, the current Ministry of Agriculture and Forestry Forest Biosecurity Strategy does not really address forward provision for breeding for resistance. A solution must be multi-pronged, with commitment from various parties.
A new approach to stopping the spread of invasive insects and pathogens: early detection and rapid response via a global network of sentinel plantings.Britton, K. O., White, P., Kramer, A., & Hudler, G.
Britton et al. (pp. 109-114) promote the development of a worldwide network of gardens sharing information on pests in order to enhance biosecurity.Published Online - 6 Jul 2010. [740.0 KB] (pdf).The Sanitary and Phytosanitary Agreement of the World Trade Organisation specifies that countries cannot regulate against unknown pests, yet many alien invasive forest pests are unknown to science prior to discovery in a new land. Many of these pests are introduced via nursery stock, but lack of pest information makes this pathway difficult to mitigate. Botanic gardens and arboreta worldwide offer a unique opportunity to help detect potential invasive threats to forest health before they spread. Monitoring pests in gardens with international collections could inform prevention activities as well as help promote early detection and rapid response to new pest incursions. While recognising the inherent value of single country-pair studies currently ongoing, and the scientific integrity expected of resulting peer-reviewed publications, we believe opportunities for synergy across these efforts and for more immediate response to new host-pest associations should be explored. The strengths and weaknesses of various current approaches to sentinel plant monitoring are described, as well as a strategy for developing a worldwide network of gardens sharing information on pests that would extend the lessons learned and direct timely information to National Plant Protection Organisations to enhance protection of natural resources.
Initial fall-spring vegetation management regimes improve moisture conditions and maximise third-year Douglas-fir seedling growth in a Pacific Northwest plantation.Dinger, E. J., & Rose, R.
Dinger & Rose (pp. 93-108) present third-year results quantifying the growth response of Douglas-fir seedlings to six herbicide treatment regimes applied during the first two years of plantation establishment. Their results demonstrate how vegetation management prescriptions can ensure successful establishment of Douglas-fir under different climatic conditions while providing a biosecurity safety net that minimises injury to plant community biodiversity.Published Online - 5 Jul 2010. [1.5 MB] (pdf).Competition for soil moisture can limit seedling growth and survival during the initial years of plantation establishment. Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco.) seedlings growing in the Mediterranean climate of western Washington (USA) contend with early-seral vegetation for soil moisture held in the upper soil layers. While research has documented improvements in seedling growth due to reductions in competition, this is the first study to present results showing how operationally oriented vegetation management regimes impact growing conditions for planted Douglas-fir seedlings in the Pacific Northwest. This paper presents third-year results quantifying seedling growth response to six herbicide treatment regimes applied during the first two years of plantation establishment. Soil moisture and seedling xylem water potential, measured during the initial two seasons were improved when competitive cover was maintained below 20%. In response to this low level of competition, height to diameter ratio of seedlings decreased below 50 and has remained low despite rapid colonisation of the vegetation community one year post-herbicide use. Third year (2008) stem volume growth was maximised by the most intense treatment. The volume increase was 808.8 cm3, a 470% improvement when compared with 141.8 cm3 in the no-action control. Herbicides restrained vegetation community growth during the years applied and, while they altered the dominance of the community, they did not eradicate any of the six plant growth habits found on the site. Results from this study demonstrate how vegetation management prescriptions can ensure successful establishment under different climatic conditions while providing a biosecurity safety net that minimises injury to plant community biodiversity.
Guest Editorial: Special Issue: IUFRO International Forest Biosecurity Conference 16 - 20 March 2009Ramsfield, T. D., & Richardson, B.
Guest Editorial: Special Issue: IUFRO International Forest Biosecurity Conference 16 - 20 March 2009Published Online - 5 Jul 2010. [361.1 KB] (pdf).
Evaluation of the strength of shaved steamed Pinus radiata poles.Walford, G. B., & Chapman, J. B.
Walford and Chapman (pp. 83-90) found that stress-wave velocity was more effective than basic density of outer-zone wood for selectiing Pinus radiata poles for structural uses. A minimum stress-wave velocity reading of 2.8 km/s is recommended. The authors conclude that New Zealand Standard3603 should be amended in the light of these findings.Published Online - 15 Jun 2010. [850.0 KB] (pdf).Bending strength of Pinus radiata (D.Don) poles is critical in a range of structural applications, such as retaining-walls. Pinus radiata poles in a wet, shaved and steamed condition were obtained from five suppliers located across the central North Island of New Zealand. This sample of poles met the stiffness (Modulus of Elasticity) value expected of normal-density poles according to New Zealand Standard3603, but their characteristic bending and compression stresses were 40% and 39%, respectively, lower than expected. Applying a maximum allowable knot size restriction (measured as the knot diameter ratio) made little difference to the results. Applying a minimum stress-wave velocity (measured using a HM-200 device) also had little effect on the derived characteristic values until the value was raised to 3.2 km/s, which would eliminate about 20% of the sample. A minimum stress-wave velocity reading of 2.8 km/s is recommended. At this level, some poles from two of the five suppliers would have to be rejected. These results indicate that pole selection based on the basic density of outer-zone wood is less effective than that using stress-wave velocity measured using a HM-200 device. It is recommended that New Zealand Standard3603 should be amended in the light of these findings.
The effect of incorporating the height of bordering trees on gap size estimations: the case of Argentinean Nothofagus pumilio forest.López Bernal, P. M., Arre, J. S., Schlichter, T. M., & Bava, J. O.
There is currently no consensus on the best methodology for gap size measurement in Argentinian Nothofagus pumilio forests, which leads to an inaccurate link between ecological studies and management guidelines. This study aimed to produce an experimental method for determining gap size which may be suitable for both forest management and ecological analysis. Based on the results obtained, López Bernal et al. (pp. 71-81) propose the use of polygonal expanded gap diameter/dominant canopy height ratio as a gap size parameter for the measurement of gap size in N. pumilio forests.Published Online - 8 Jun 2010. [2.6 MB] (pdf).For forests of Nothofagus pumilio (Poepp et Endl.) of Chubut province, Argentina, the Forest Office recommends a type of group selection as the system of regeneration. This method involves the creation of gaps in the canopy. Gap size determines seedling recruitment and sapling growth in these forests as a result of dry summers. However, in the context of N. pumilio forest management, there is no consensus on the best methodology for gap size measurement and this leads to an inaccurate link between ecological studies and management guidelines. This study aimed to produce an experimental method for determining gap size which may be suitable for both forest management and ecological analysis. The sizes of fourteen artificially created forest gaps were determined under a range of scenarios involving two definitions of gap limit, six calculation methods and using either the gap surface or the ratio between the gap diameter and canopy height. These scenarios were compared based on their correlation with three ecological variables (incident radiation, soil moisture and sapling growth). No differences between gap limit definitions or between calculation methods were found. The use of the gap diameter/canopy height ratio significantly improved the correlation with ecological variables. Also, the correlation between dominant height and soil moisture was better than average height with soil moisture. Based on these results, we propose the use of polygonal expanded gap diameter/dominant canopy height ratio as a gap size parameter for the measurement of gap size in N. pumilio forests. This parameter will be applicable to both ecological research and forest management.
Susceptibility to intra-ring checking in Pinus radiata: potential for genetic improvement.Kumar, S., Cown, D., Ivković, M., & Burdon, R. D.
Kumar et al. (pp. 61 -70) document assessment methods and genetic parameters (heritability, genotype-environment interaction, genetic correlations) of internal checking. The frequency of internal checking generally decreases with log height. Estimated heritabilities indicated a moderate genetic control, and the estimated between-site genetic correlations suggested that the magnitude of genotype-environment interactions would be lower compared to those generally observed for diameter, but higher compared to those for wood density. Strategies for culling undesirable genotypes from the breeding and production populations are also discussed.Published Online - 18 May 2010. [922.9 KB] (pdf).ntra-ring ("internal") checking is one of several wood phenomena that downgrade appearance-grade products of Pinus radiata D.Don. A recently developed increment core-based method has proved cost-effective for large-scale non-destructive assessment. The main objectives of this paper were to document assessment methods and genetic parameters (heritability, genotype-environment interaction, genetic correlations) of internal checking. The greatest incidence of internal checking appears in sapwood outside the heartwood zone, while the heartwood itself is usually check-free. The frequency of internal checking generally decreases with log height. Estimated heritabilities (mostly > 0.30) indicated a moderate genetic control, and the estimated between-site genetic correlations (ca. 0.75) suggested that the magnitude of genotype-environment interactions would be lower compared to those generally observed for diameter, but higher compared to those for wood density. Prior estimates of genetic correlations of internal checking with diameter and wood density had been near-zero and about -0.50, respectively. Strategies for culling undesirable genotypes from the breeding and production populations are also discussed.
A review of New Zealand kauri (Agathis australis (D.Don) Lindl.): its ecology, history, growth and potential for management for timber.Steward, G. A., & Beveridge, A. E.
Steward & Beveridge (pp.33-59) review the ecology, history, growth and uses of kauri (Agathis australis (D.Don) Lindl.), the only member of the Araucariaceae indigenous to New Zealand.Published Online - 8 Mar 2010. [2.8 MB] (pdf).Kauri (Agathis australis (D.Don) Lindl.) is endemic to New Zealand, where it is the only indigenous member of the Araucariaceae. It has the most southerly distribution of any species in the genus and is currently confined to the warm temperate areas of the North Island. At the time of European settlement, forests containing kauri covered 1 000 000 ha or more in New Zealand. Following uncontrolled logging, land clearance for alternative land use and destruction by fire, only 7500 ha of virgin or primary forest remain, mainly in conservation reserves. An additional 60 000 ha of scrub/shrubland and secondary forest contain varying amounts of regenerating kauri.
Kauri is reputed to produce greater volumes of wood from single stems than any other timber tree in the world. Its timber is regarded as one of the finest due to qualities of decay resistance and dimensional stability under moist conditions. A wide range of products was developed by Maori and European settlers. Kauri timber and gum made a substantial contribution to the physical and economic development of New Zealand between 1830 and 1900.
Agathis australis shares a number of biological characteristics with lowland Agathis species found in the tropics and subtropics. These include a juvenile form with narrow tapering crown; mature emergent trees with massive, spreading, dome-shaped crowns and upwardly-arched branches; self-pruning in sapling and pole-stage trees; flaking bark; wind-dispersed, small-winged seeds formed in cones that disintegrate at time of seed maturity while still on the tree; and only a few months of seed viability after shedding. Juvenile trees with taproots and mature trees with wide-spreading lateral roots and descending peg roots are windfirm, assisting longevity. Although surviving trees of massive dimensions (35 m diameter) are usually hollow, their life span may be 1500 years or more. Large kauri have a podsolising effect on some acidic soils, making them less fertile. Efficiency in the use of water and nutrients has enabled the species to become dominant on infertile and drought-prone ridge tops. Observations of growth in natural stands indicate mean annual increment of 2.56.0 mm in diameter and 0.3 m in height.
Interplanting of kauri in scrub and shrubland developed on former kauri forest sites has produced poor results. Mean annual increments of 6.9 mm in diameter and 0.44 m in height have been recorded in young untended plantations. Greater success has been achieved through attention to site selection, improved establishment techniques and silvicultural tending. The most suitable sites for planting are those with fertile, well-drained, light-textured soils, a warm, humid climate, and a history of previous occupation by broadleaved (angiosperm) plant species. Current research suggests that rotation length can be reduced by best-practice management, and that planted stands could be a continuing source of kauri timber in the future.
Sawing and grade recovery of 25-year-old Eucalyptus fastigata, E. globoidea, E. muelleriana and E. pilularis.Jones, T. G., McConnochie, R. M., Shelbourne, T., & Low, C. B.
Jones et al. (pp. 19-31) evaluated the processing characteristics of four Eucalyptus species at 25 years of age to determine if these species could be used to produce high-quality timber on shorter rotations. The butt- and second logs of 15 trees of each species were quarter-sawn and flat-sawn respectively, and the boards assessed for shrinkage and distortion, visual and mechanical properties, and surface hardness.Published Online - 19 Feb 2010. [801.4 KB] (pdf).The processing characteristics of 25-year-old Eucalyptus fastigata Deane et Maiden, E.globoidea Blakely, E. muelleriana Howitt and E. pilularis Sm. from Rotoehu Forest, New Zealand, were evaluated to determine if these species could be used to produce high-quality timber on shorter rotations. The butt- and second logs of 15 trees of each species were quarter-sawn and flat-sawn respectively, and the boards assessed for shrinkage and distortion, visual and mechanical properties, and surface hardness.
Growth-stress release during sawing, combined with end-checking during drying, resulted in board end-splitting that reduced the sawn recovery in E. fastigata compared with the other species, and produced high levels of crook in the quarter-sawn boards of all species. There was no surface checking and little or no drying collapse and internal checking.
The proportions of visual clears and No.1 cuttings grades were low, particularly for E.muelleriana and E. pilularis, due to the presence of knots. The boards of all species had high values of density, modulus of elasticity and surface hardness, and machine stress grades of MSG10 to MSG15.
These species have the potential to produce high-quality timber on 25-year rotations, but pruning will be required to improve visual grades so that a higher proportion of boards can be used in appearance applications.
Determining and projecting realised genetic gains: Results from early-stage spruce improvement programmes in New Brunswick, Canada.Weng, Y, Tosh, K, & Fullarton, M.
Weng et al. (pp 5 - 17) investigated realised gains from planting improved seedlots in large plots representing early-stage tree improvement activities for Black Spruce and White Spruce in New Brunswick, Canada. Realised gains in this study differed greatly from those observed in the corresponding genetic tests using small-plots. This suggests that using a small plot size for trials could greatly bias the actual gains possible on a plantation-scale, particularly when using seedlots obtained from orchards.Published Online - 20 Jan 2010. [677.1 KB] (pdf).Two series of realised genetic gain tests of large plots, one for black spruce (Picea mariana (Mill.) B.S.P.) and one for white spruce (Picea glauca [Moench] Voss), were established in the early 1990s in New Brunswick, Canada, to investigate realised gains from planting improved seedlots representing early-stage tree improvement activities. Individual-tree growth was recorded up to age 15 (one-quarter of their rotation age). Four improved seedlots were included in the black spruce gain test. Planting the superior stand seedlot (CAN101) could obtain moderate gain (7.0% in volume/tree and 3.5% in volume/ha at age 15). Growth improvement for the seedlot (UNROG) collected from a seedling seed orchard (FRA_SSO) established using phenotypically selected plus trees was negligible but genetic roguing improved the FRA_SSO seedlot's growth, resulting in 3.3 and 2.1% increase in 15-yr volume per tree and per hectare, respectively. The highest gain was observed by deploying the elite half-sib family (01-15), which resulted in a gain of 27.6% in 15-yr volume/ha. Three improved seedlots were included in the white spruce realised-gain test. The seedlot (OVSSO) collected from a provenance seedling seed orchard had 9.2% more volume/ha at age 15 years. Much higher gains were observed in the seedlots collected from an unrogued clonal seed orchard (DNR_CSO). Mixed cone collections from the DNR_CSO achieved 25.6% more volume/ha at age 15 than the unimproved seedlot. Practicing supplemental mass pollination with unimproved pollen in the DNR_CSO greatly reduced its seedlot gains, i.e. 12.9% in 15-yr volume/ha. In both tests, the gain varied with age or site index. Realised gains in this study differed greatly from those observed in the corresponding genetic tests using small-plots. This suggests that using a small plot size for trials could greatly bias the actual gains possible on a plantation-scale, particularly when using seedlots obtained from orchards.
NZJFS Editor , Dr Ruth Falshaw, introduces Volume 40.Published Online - 20 Jan 2010. [245.4 KB] (pdf).
Acknowledgement to refereesThe Editor is grateful to the following people who have acted as referees for papers submitted to the New Zealand Journal of Forestry Science during the preparation of Volume 40.Published Online - 15 Nov 2010. [286.7 KB] (pdf).